Fire Protection Systems, Third Edition is designed to provide accurate and authoritative ,
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FIRE PROTECTION SYSTEMS THIRD EDITION
CHAIR
Jonathan Kulpit, PE, CPD CPD,, CFPS CONTRIBUTORS
Wally Barker|Scott Bartmess, PE, CFPS |Allen Bunner Brian Conway, Conway, PE | Jerry Graupman | Bill Howerton Jonathan Kulpit, PE, CPD, CFPS | Daniel Lampke, M.S.F.P.E. Matthew Sciarretti, PE, CPD, CFPS, LEED AP BD+C | Julie Sherby Bella Treyger | Greg Trombold TECHNICAL REVIEWERS
Anthony Curiale, CPD, LEED AP | Carol Johnson, CPD, LEED AP, CFI Larisa Miro, CPD | April Ricketts, PE, CPD Frank Sanchez, CPD, GPD | Susan Smith | Karl Yrjanainen, PE, CPD James Zebrowski, PE, CPD, FASPE | Stephen Ziga, CPD, SET, CFPS Thura Zin, CPD CP D, GPD EDITOR
Gretchen Pienta GRAPHIC DESIGNER
Nadine Saucedo
ABOUT ASPE
The American Society of Plumbing Engineers (ASPE), founded in 1964, is the international organization for professionals skilled in the design and specication of plumbing systems.
ASPE is dedicated to the advancement of the science of plumbing engineering, to the professional growth and advancement of its members, and to the health, welfare, and safety of the public. The Society disseminates technical data and information, sponsors
activities that facilitate interaction with fellow professionals, and, through research and education programs, expands the base of knowledge of the plumbing enginee ring industry. ASPE members are leaders in innovative plumbing design, effective materials and energy use, and the application of advanced techniques from around the world.
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Fire Protection Systems
Figures
Figure 5-1
Continuous-Line Fixed-Temperature Heat Detector .........................................26
Figure 5-2
Rate-Compensation Heat Detector ................................................... ..................26
Figure 5-3
Rate-of-Rise Heat Detector .................................................................................. 27
Figure 5-4
Photoelectric Light-Obscuration Smoke Detector .............................................27
Figure 5-5
Photoelectric Light-Scattering Smoke Detector .................................................27
Figure 6-1
The Fire Triangle..................................................................................................... 31
Figure 7-1
Fire Pump System .................................................. ................................................. 35
Figure 7-2
Vertical Turbine Fire Pump.................................................. .................................. 35
Figure 7-3
Impeller Rotation....................................................................... .............................. 36
Figure 7-4
Hydropneumatic Tank .................................................. .......................................... 38
Figure 7-5
Example Pump Curve, 1,000-gpm Rated Pump...............................................39
Figure 8-1
Post Indicator Valve................................................................................................ 41
Figure 9-1
Wet Pipe Sprinkler System................................................. .................................. 49
Figure 9-2
Dry Pipe Valve........................................................................................................ 49
Figure 9-3
Preaction Valve Riser ................................................... .......................................... 49
Figure 9-4
Deluge Valve Riser ................................................................................................. 50
Figure 9-5
Antifreeze System .................................................................................................. 50
Figure 9-6
Vane-Type Water Flow Indicator ........................................................................ 54
Figure 9-7
Alarm Check Valve Riser ....................................................................................... 55
Figure 9-8
Design Area Curve Example ................................................................................ 58
Figure 10-1
Axisymmetric Flow .................................................................................................. 62
Figure 11-1
Plan View of Sprinkler System................................................... .......................... 73
Figure 11-2
Hydraulically Most Remote Area.........................................................................74
Figure 11-3
Hydraulic Node Points ................................................. .......................................... 75
Figure 11-4
Illustration of Density/Area Method Calculation..............................................77
Figure 11-5
Example 11-1 Plan View...................................................................................... 80
Figure 11-6
Standpipe System with Looped Piping ..............................................................81
Figure 11-7
Water Flow Paths in Loops ................................................. .................................. 81
Figure 14-1
High-Pressure Carbon Dioxide Cylinder Arrangement ...................................96
Figure 14-2
Summary of Carbon Dioxide Applications........................................................97
Figure 14-3
CO2 Concentration Conversion Factors ........................................................... 100
Table of Contents
xi
Tables
Table 4-1
Test and Inspection Frequency of Water-Based Suppression Systems........ 22
Table 5-1
Detector Applications Summary ......................................................................... 29
Table 6-1
Classications of Combustible Materials................................................. ......... 31
Table 7-1
Centrifugal Fire Pump Component Sizing Data ............................................... 37
Table 8-1
Flow Rate Required to Produce a Velocity of 10 fps in a Main .................. 42
Table 9-1
Sprinkler Temperature Ratings and Temperature Classication Color Codes .......................................................................................................... 53
Table 9-2
Approved Materials for Sprinkler System Pipe .............................................. 54
Table 9-3
Spacing for Standard Pendent and Upright Sprinklers ................................. 56
Table 9-4
Drain Sizes for Sprinkler Systems....................................................... ................ 57
Table 9-5
Hanger Rod Sizing ................................................................................................ 57
Table 9-6
Maximum Distance Between Hangers, ft........................................................... 57
Table 9-7
Underground Main Flushing Flow Rates................................................... ......... 59
Table 10-1
Density of Water at Varying Temperatures ..................................................... 61
Table 10-2
Pipe Roughness Coefcients ........................................................ ........................ 64
Table 10-3
Equivalent Pipe Lengths for Fittings, ft....................................................... ........ 65
Table 10-4
Equivalent Length Multipliers for C Factors Other than C = 120 ................ 65
Table 10-5A Water Flow Table, 1-inch Schedule 40 Steel Pipe ......................................... 66 Table 10-5B Water Flow Table, 1¼-inch Schedule 40 Steel Pipe ..................................... 67 Table 10-5C Water Flow Table, 1½-inch Schedule 40 Steel Pipe ..................................... 68 Table 10-5D Water Flow Table, 2-inch Schedule 40 Steel Pipe ......................................... 69 Table 10-5E
Water Flow Table, 2½-inch Schedule 40 Steel Pipe ..................................... 70
Table 10-5F
Water Flow Table, 3-inch Schedule 40 Steel Pipe ......................................... 71
Table 10-5G Water Flow Table, 4-inch Schedule 40 Steel Pipe ......................................... 72 Table 11-1
Inside Diameters for Schedule 10 and Schedule 40 Steel Pipe, in. ............ 75
Table 11-2
Equivalent Lengths of Common Fittings (for Schedule 40 Pipe), ft .............. 76
Table 11-3
Step 1 of the Example Calculation in NFPA 13 Format ................................ 78
Table 11-4
Steps 1 and 2 of the Example Calculation in NFPA 13 Format ................... 78
Table 11-5
Steps 1 and 2 and XX of the Example Calculation in NFPA 13 Format .................................................... ................................................ 79
Table 11-6
Common Area Modications .............................................................................. 79
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Fire Protection Systems Table 12-1
Foam Characteristics.................................................... .........................................84
Table 14-1
Minimum Carbon Dioxide Concentrations for Extinguishment ....................... 99
Table 14-2
Flooding Factors .................................................................................................. 100
Table 14-3
Flooding Factors for Specic Hazards ..................................................... .......101
Table 16-1
Clean Agent Information...................................................... .............................. 108
Table 16-2
Chemical Impacts on the Environment........................................................ ......110
Table 16-3
Minimum Design Concentrations for Five-Minute Exposure .........................110
Table 16-4
K Values for Equation 16-2......................................................... ...................... 112
Table 16-5
Clean Agent Comparison Table................................................. .......................113
Table 17-1
Portable Fire Extinguisher Classications ........................................................115
Table 17-2
Travel Distances to Portable Fire Extinguishers ..............................................116
Table 17-3
Hydrostatic Testing Requirements....................................................... ..............116
Table of Contents
1: FIRE PROTECTION FUNDAMENTALS ...................................................................... 1
Codes and Standards................................................................................................................1 Authorities Having Jurisdiction .................................................................................................2 Fire Protection Organizations ..................................................................................................3 National Fire Protection Association.........................................................................3 UL ................................................. ..................................................................................3 FM Global ................................................... ..................................................................4 Fire Prevention ............................................................................................................................4 Passive Fire Protection ...............................................................................................................5 Fire-Rated Barriers ......................................................................................................5 Structural Stability .......................................................................................................5 Direct Means of Egress ...............................................................................................5 Detection and Notication ........................................................................................................6 Suppression Systems ..................................................................................................................6 Development of the Life Safety Code.................................................. ...................7 2: BASIC CHEMISTRY AND PHYSICS OF FIRE ............................................................. 9
Smoke ...........................................................................................................................................9 Smoke Control............................................................................................................ 10 Material Combustibility................................................. ......................................................... 10 Fire Extinguishing ..................................................................................................................... 11 Exits and Openings ................................................................................................................. 13 Fire Barriers ..............................................................................................................................13 3: FIRE SAFETY IN BUILDING DESIGN ...................................................................... 13
Fire Safety Personnel.............................................................................................................. 14 New Construction ..................................................................................................................... 14 Remodeling ............................................................................................................................... 15 4: COMMISSIONING, TESTING, AND MAINTENANCE ............................................. 17
Fire Protection System Commissioning ................................................................................. 17 Commissioning Team .................................................. ............................................... 17 Commissioning Authority ..................................................................................... 18 Fire Commissioning Agent................................................................................... 18 Registered Design Professional........................................................................... 18 Integrated Testing Agent ..................................................................................... 18 Documentation ........................................................................................................... 18 Owner’s Project Requirements ............................................................................. 19 Basis of Design .................................................................................................... 19 Commissioning Plan ............................................................................................. 19 Final Commissioning Report ................................................................................ 19 Commissioning Process ............................................................................................. 19
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Fire Protection Systems Planning Phase.................................................. .................................................... 19 Design Phase ......................................................................................................... 20 Construction Phase ................................................... ............................................ 20 Occupancy Phase ................................................................................................. 20 Re-Commissioning and Retro-Commissioning .................................................. ..... 20 Integrated Testing....................................................................................................................20 Maintenance ............................................................................................................................. 21 Inspection .................................................................................................................... 21 Testing ........................................................................................................................ 21 Cleaning .................................................................................................................... 22 Preventive Maintenance ......................................................................................... 22 Repair and Replacement ........................................................................................ 22 Carbon Monoxide Detection ................................................................................................. 23 5: FIRE DETECTION SYSTEMS ................................................................................... 23
Basic Components of a Fire Alarm System................................................... ...................... 24 Manual vs. Automatic Detection Systems ............................................................................ 25 Types of Detection Devices.................................................................................................... 25 Heat Detectors........................................................................................................... 25 Fixed-Temperature Heat Detectors..................................................................... 26 Rate-Compensation Type..................................................................................... 26 Rate-of-Rise Type ................................................................................................. 27 Smoke Detectors........................................................................................................ 27 Ionization Type ................................................ ..................................................... 27 Photoelectric Type ................................................................................................ 27 Flame Detectors......................................................................................................... 27 Water Flow Detectors .................................................. ............................................ 28 Choosing a Detector Device .................................................................................................. 28 Detector Location and Spacing............................................................................................. 30 Evacuation Signaling.................................................. ............................................................. 30 6: FIRE SUPPRESSION OVERVIEW ............................................................................ 31
Extinguishing Agents................................................................................................... ............. 31 Water ..........................................................................................................................32 Alternative Suppression Systems .......................................................................................... 33 7: FIRE PUMPS .......................................................................................................... 35
Pump Components ................................................................................................................... 36 Booster Pumps .......................................................................................................................... 37 Spare Pumps ............................................................................................................................ 37 Maintaining Pressure.................................................. ............................................................. 38 Jockey Pumps ................................................. ............................................................ 38 Hydropneumatic Tanks ................................................ ............................................. 38 Pump Curves ................................................ ............................................................................. 39 8: PRIVATE MAINS, STANDPIPES, AND HOSE SYSTEMS .......................................... 41
Standpipe and Hose Systems ................................................. .............................................. 42 Standpipe Requirements.......................................................................................... 43 Standpipe Classes .................................................................................................... 43 Standpipe System Types ......................................................................................... 43 Flow and Pressure Requirements ............................................................................ 44 Flow Rates .................................................. ............................................................ 44 Pressure Requirements .......................................................................................... 44
Table of Contents
Hose Connections .................................................. .................................................... 44 Material Selection................................................. .................................................... 45 System Acceptance Tests ......................................................................................... 45 9: AUTOMATIC SPRINKLER SYSTEMS ...................................................................... 47
History of Fire Sprinklers .................................................. ..................................................... 47 NFPA 13.................................................. .................................................................... 47 Fire Sprinkler System Design................................................................................................. 47 Basis of Design .......................................................................................................... 48 Sprinkler System Types............................................................................................ 48 Wet Pipe Systems................................................................................................. 48 Dry Pipe Systems .................................................................................................. 48 Preaction Systems ................................................................................................ 49 Deluge Systems ..................................................................................................... 50 Combined Dry Pipe and Preaction Sprinkler Systems ..................................... 50 Antifreeze Systems .................................................. ............................................ 50 Occupancy Classications................................................ ...................................................... 51 Light Hazard .................................................. ............................................................ 51 Ordinary Hazard Group 1 ................................................ ..................................... 51 Ordinary Hazard Group 2 ................................................ ..................................... 51 Extra Hazard Group 1 ............................................................................................ 52 Extra Hazard Group 2 ............................................................................................ 52 Components and Materials.................................................................................... ................ 52 Sprinklers .................................................................................................................... 52 Sprinkler Types...................................................................................................... 53 Piping ..........................................................................................................................54 Alarms .........................................................................................................................54 Other Components .................................................................................................... 55 Basic Installation Requirements ............................................................................................. 55 Area Limitations......................................................................................................... 55 Spacing per Sprinkler Head and Between Sprinkler Heads............................ 55 Deector Positions ................................................. .................................................... 56 Obstructions to Sprinkler Discharge ................................................. ..................... 56 System Drains ............................................................................................................ 57 Hanging and Restraint Requirements .................................................................... 57 Design Approaches ................................................................................................................. 57 Pipe Schedule Systems............................................................................................. 57 Hydraulically Calculated Systems ......................................................................... 58 Design and Construction Documents..................................................................................... 58 System Acceptance ................................................................................................................. 59 Hydrostatic Tests ........................................................................................................ 59 Pneumatic Tests .......................................................................................................... 59 Flushing........................................................................................................................59 Operational Tests ................................................... ................................................... 59 10: BASIC HYDRAULICS FOR SPRINKLER SYSTEMS ................................................. 61
Assumptions and Simplications............................................................................................ 61
Compressibility .......................................................................................................... 61 Density and Temperature ........................................................................................ 61 Viscosity ................................................... ...................................................................61 One-Dimensional Flow ................................................ ............................................. 62
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Fire Protection Systems Results of Assumptions and Simplications ........................................................... 62
Pressure Losses in Pipes .......................................................................................................... 63 Energy Loss .................................................................................................................63 Water Pressure.......................................................................................................... 63 Absolute Pressure vs. Gauge Pressure .................................................................. 63 Pressure Due to Elevation ........................................................................................ 63 The Hazen-Williams Equation................................................................................. 64 Water Flow Tables .................................................................................................... 65 Friction Losses for Fittings and Valves ................................................................... 65 Water Exiting the Pipe ........................................................................................................... 66 Density/Area Method............................................................................................................. 73 11: HYDRAULIC CALCULATIONS .............................................................................. 73
Beginning the Calculation ........................................................................................ 74 Equivalent K Factors ................................................................................................. 77 Result ...........................................................................................................................77 Elevation Changes ................................................................................................................... 77 Hydraulic Calculation Forms .................................................................................................. 78 Area Modications .................................................................................................................. 79 Looped and Gridded Piping ................................................... ............................................. 80 12: FIREFIGHTING FOAM ......................................................................................... 83
How Foams Extinguish Fire..................................................................................................... 83 Criteria for Foam to Be Effective ........................................................................... 83 Foam Characteristics .................................................. ............................................................. 84 Drainage Rate ........................................................................................................... 84 Expansion Rate .......................................................................................................... 84 Types of Foams ................................................... ..................................................................... 84 Aqueous Film-Forming Foam ................................................................................... 84 Alcohol-Resistant Aqueous Film-Forming Foam.................................................... 85 Protein Foam .................................................. ............................................................ 85 Fluoroprotein Foam................................................................................................... 85 Alcohol-Resistant Fluoroprotein Foam.................................................................... 85 Film-Forming Fluoroprotein.................................................. .................................... 85 Alcohol-Resistant Film-Forming Fluoroprotein ................................................. ..... 85 Class A Foam Concentrate ................................................. ..................................... 85 Proportioning............................................................................................................................ 85 Percentages ................................................................................................................ 86 Proportioning Methods............................................................................................. 86 Pre-Mix/Dump-In ............................................................................................ ..... 86 Balanced-Pressure Proportioning Systems ................................................... ..... 86 Line Proportioner .................................................................................................. 86 Around the Pump ................................................................................................. 86 Water-Driven Foam Proportioner ................................................. ..................... 86 Water Pressure.......................................................................................................... 86 Discharge Devices ................................................................................................................... 86 Guidelines for Fire Protection with Foams .......................................................................... 87 Storage...................................................................................................................................... 87 Environmental Impact of Foam................................................. ............................................. 87 13: WATER MIST SYSTEMS ........................................................................................ 89
History of Water Mist ............................................................................................................. 89 Performance Principles of Water Mist ................................................... ............................. 89
Table of Contents
Conditions ...................................................................................................................90 Standards and Approvals ..................................................................................................... 90 Water Mist System Types ...................................................................................................... 91 Single Fluid................................................................................................................. 91 Twin Fluid .................................................................................................................... 92 System Design .......................................................................................................................... 92 Comparisons to Other Fire Protection Technologies ................................................... ...... 94 Water Mist vs. Sprinklers......................................................................................... 94 Water Mist vs. Water Spray .................................................................................. 94 Water Mist vs. Clean Agents .................................................................................. 94 Technical Issues to Consider .................................................................................... 94 14: CARBON DIOXIDE SYSTEMS .............................................................................. 95
Carbon Dioxide as a Fire Suppression Agent ................................................................... 95 System Applications ................................................................................................ 96 Advantages and Disadvantages .......................................................................... 97 Alarms and Evacuation ........................................................................................................... 98 Specications............................................................................................................................98 Cylinders and Scales ................................................. ............................................................. 98 Pipe Sizing Calculations ......................................................................................................... 99 Pressure-Relief Venting Formula .........................................................................100 15: DRY AND WET CHEMICALS ..............................................................................103
Dry Chemical Extinguishing Systems ..................................................................................103 Dry Chemical Agents ..............................................................................................103 How Dry Chemicals Extinguish Fire ......................................................................104 System Types ...........................................................................................................104 Local Application ...............................................................................................104 Handheld Hose Lines ..........................................................................................104 Total Flooding ................................................... ..................................................104 Storage and Maintenance ................................................. ...................................105 Wet Chemical Extinguishing Systems .................................................................................105 Wet Chemical Agents .................................................. ...........................................105 How Wet Chemicals Extinguish Fires ...................................................................106 System Description ..................................................................................................106 16: CLEAN AGENTS ................................................................................................107
Development of Clean Agents ............................................................................................107 Types of Clean Agents .........................................................................................................108 Extinguishing Methods ..........................................................................................................108 Chemical Suppression..............................................................................................108 Evaporative Cooling at the Flame’s Reaction Zone.............................................108 Flame Cooling ..........................................................................................................109 Environmental Impact ............................................................................................................109 Safety ................................................... ...................................................................................110 System Design ........................................................................................................................111 Design Procedure .................................................. ...................................................111 Conclusions/Comparisons................................................. ....................................................113 17: PORTABLE FIRE EXTINGUISHERS......................................................................115
Classications .........................................................................................................................115
Installation...............................................................................................................................116 Maintenance ...........................................................................................................................116 INDEX
..................................................................................................................117
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1
Fire Protection Fundamentals
1
Uncontrolled fires are dangerous to people and property. Fire protection is a multifaceted field dedicated to preventing and/or mitigating the effects of these fires. �e fire protection discipline has many distinct parts, including prevention, passive protection, suppression, detection, and notification. An additional element, smoke management, is also part of fire protection. Smoke management is required in some occupancies and can be a challenging aspect of a project, so identifying when smoke management is required is critical.
CODES AND STANDARDS Every person involved in building construction or maintenance should be aware that many aspects of a facility are required to conform to standards and codes, which give engineers, architects, and contractors the guidance they need to design and build safe environments for human occupancy. A code is a set of rules and regulations adopted by the authority having jurisdiction (AHJ) to ensure minimum safety requirements. A standard is defined as a set of recommended guidelines established by a professional organization that can be used as the basis for the design, installation, and maintenance of a certain system. Fire protection codes and standards were developed to protect the lives of building occupants as well as properties and their contents. Anyone working on a fire protection system should have knowledge of the wide range of applicable standards and codes that apply to such systems and know where to find a reference when required. In the United States, the most widely accepted standards are issued by the National Fire Protection Association (NFPA). �e codes that adopt these standards are typically issued by the governing state, with amendments added by counties and/or cities. �e International Building Code (IBC) and the International Fire Code (IFC) are two examples of codes commonly encountered by fire protection professionals. Standards may require the equipment and materials used in a fire protection system to be listed or labeled by an organization that has a product certification program. Examples of such organizations are UL, FM Global, and ASTM International. Generally, the purpose of a fire code is to set minimum levels of acceptability in the design, installation, and maintenance of fire protection systems. Many codes, as well as insurance company standards, establish performance objectives by providing specific requirements. �ese performance-based codes leave it up to the designer to determine how to meet those objectives. More than one solution is usually applicable because new and original ideas are constantly being developed. Performance-based codes do not allow building inspectors or plan reviewers to grant waivers from prescriptive code requirements. Safe alternate substitutions, however, may be acceptable, and approval may be granted for such an installation if an equivalent level
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Fire Protection Systems
of safety can be achieved. All local regulations required by the AHJ are mandatory and/or enforceable. When applicable codes conflict, the most stringent or exclusive requirement is enforceable. Where multiple codes apply or the requirements for an installation are not clear, the local AHJ should be consulted. It must be clearly understood that the applicable code, or any governing code, does not abrogate, nullify, or abolish any law, ordinance, or rule adopted by the local governing AHJ.
AUTHORITIES HAVING JURISDICTION According to NFPA, the AHJ is the organization, office, or individual responsible for approving an installation, piece of equipment, or procedure. AHJs may be governmental, such as federal, regional, state, or local departments. �ey may also be individuals such as fire chiefs, plan reviewers, or building inspectors. An insurance company representative may also be an AHJ. It is important to identify all applicable AHJs at the beginning of a project because they all will have a say in the project�s requirements. Before any building is built or remodeled, code dictates that a permit shall be secured from the AHJ. Project approval and the permit are typically issued by the local building department and/or fire prevention bureau. Permits are official documents issued in the name of the owner to a contractor prior to the start of construction, and they are not transferable. �e permit process provides AHJs with information regarding what, where, how, and when a specific building that is under their jurisdiction will be built or altered. Further, it allows the building official to review and approve devices, safeguards, and procedures that may be needed to ensure the safe use or occupancy of a building. For a project of appreciable size and scope, a plan reviewer is typically required to review the construction plans for compliance with the code. If it is determined that the planned construction meets the minimum requirements of all applicable codes and standards, the permit is issued. If all requirements are not met or if the plan reviewer requires clarifications, revisions to and a resubmission of the construction plans to the building department may be required. Changes in occupancy, storage (including arrangement, commodity, or quantity), manufacturing process, or physical building alterations or upgrades also require a permit and plan review. When a project is being developed, the following steps usually take place: 1. Project design 2. Permitting 3. Construction/installation 4. Inspection and testing 5. Issuance of the certificate of occupancy AHJs should be included as early as possible and in all steps of a project. Before the certificate of occupancy is issued, as well as during construction, inspections may be performed by the building and/or fire inspector. �e purpose of an inspection is to verify that construction is being completed in accordance with the approved plans and applicable codes and standards. It is common for fire inspectors to require full functional testing of fire protection and life-safety systems. Aer construction is complete and the certificate of occupancy is issued, the relationship between the owner (or the designated representative) and the AHJ is not over. �e owner
Chapter 1: Fire Protection Fundamentals
is responsible for the inspection, testing, and maintenance of all aspects of the building�s fire protection system, including fire barriers, egress routes, emergency lighting, emergency signage, smoke detectors, fire alarms, and fire sprinklers. �e AHJ is responsible for enforcing compliance with fire and life-safety requirements to help ensure the safety of building occupants and first responders. Emergency response plans should be developed and practiced by occupants, and a schedule and record of fire drills, training, and required fire protection system inspection, testing, and maintenance should be maintained. �ese plans and records must be retained by the owner and inspected by the AHJs. �e owner is responsible for maintaining their property and the systems and procedures that protect the safety of its occupants. If an AHJ finds a property that is not maintained to an acceptable level of safety, the owner can be fined, and the property�s certificate of occupancy can be revoked.
FIRE PROTECTION ORGANIZATIONS Many important organizations are associated with the fire protection industry. �ree of these organizations that are important to recognize are NFPA, UL, and FM Global. National Fire Protection Association NFPA is a nonprofit technical and educational organization dedicated to the protection of lives and property from fire. �e association was founded in 1896 when the need for a single standard regarding sprinkler installation in buildings was recognized. �e association administers a standards-developing program and publishes fire and life-safety standards and codes that are used by fire protection professionals, insurance companies, businesses, and governments. NFPA also provides fire information and statistics to the fire protection field, conducts onsite investigations of significant fires, and develops publications and training programs. �ese are oen the basis of education for the fire protection community and the general public. NFPA is a membership organization consisting of fire service personnel, engineers, contractors, insurers, business and industry representatives, government officials, architects, educators, volunteers, and private citizens. NFPA standards do not have the power of enforcement; they are strictly advisory. However, these standards have been adopted as the basis for most of the applicable fire protection codes, which have enforcing power. Some of the NFPA standards applicable to plumbing engineering are: u NFPA 13: Standard for the Installation of Sprinkler Systems u NFPA 14: Standard for the Installation of Standpipe and Hose Systems u NFPA 20: Standard for the Installation of Stationary Pumps for Fire Protection u NFPA 24: Standard for the Installation of Private Fire Service Mains and eir Appurtenances u NFPA 25: Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems UL UL is a safety consulting and certification company dedicated to promoting safe living and has its roots in electrical and fire safety. UL was established in 1894 and published its first standard, Tin Clad Fire Doors, in 1903. �e following year, the UL Mark made its debut with the labeling of a fire extinguisher.
3
4
Fire Protection Systems
UL supports manufacturers, regulatory authorities, building owners, and insurance companies with certification and customized testing services for a variety of fire suppression equipment, including products for residential and commercial sprinkler systems. UL tests and certifies sprinklers and nozzles to standards such as the following: u UL 199: Standard for Automatic Sprinklers for Fire Protection Service u UL 1767: Standard for Early-Suppression Fast-Response Sprinklers u UL 1626: Standard for Residential Sprinklers for Fire Protection Service u UL 2351: Standard for Spray Nozzles for Fire Protection Service Other notable UL life-safety standards include: u UL 217: Standard for Smoke Alarms u UL 268: Smoke Detectors for Fire Alarm Systems
FM Global FM Global performs research and testing, offers guidance, and provides insurance in the fire protection field. It was founded in 1835 when it became apparent that large industrial and commercial companies needed fire insurance coverage. FM Global is similar to UL in that it tests equipment, devices, and systems to determine if their reliability and efficiency will receive the FM Approved mark. �e FM Approval Guide lists all products, devices, equipment, and systems approved by FM Global. �e guide also includes details of installation and materials. FM Global publishes its own requirements in FM Global Property Loss Prevention Data Sheets; however, some NFPA standards are adopted in their entirety. FIRE PREVENTION Contractors, owners, building occupants, and even transient guests can play a part in fire prevention. �e best protection from a fire is for a fire to never start in the first place. �is is why it is important for everyone to do their part in fire prevention. It is well understood that children must be taught that fires are dangerous and can quickly become uncontrolled; however, oen overlooked or underestimated is the fact that adults also must be trained to understand the dangers of fire in their daily lives. Hazards exist, whether they be in the kitchen in a home or in an industrial process in the workplace. Education is the heart of fire prevention. When fire risks are understood, safety and practical fire prevention can be practiced. Precautions such as prohibiting smoking and maintaining good housekeeping are of paramount importance. Following standards and manufacturers� instructions for the installation and use of building systems and components, especially those involving electricity or combustion, can also help prevent a fire. Building construction and industrial processes can put a facility at risk of fire. A heightened sense of caution and preparedness needs to be exercised under the following conditions due to their inherent danger: u During welding, soldering, or brazing operations u In the vicinity of flammable or combustible materials storage u In areas with an accumulation of waste materials u When an open flame is used for any reason u When building fire protection systems are impaired During any of the above conditions, the code or the AHJ may require a dedicated person or persons qualified for the duty to conduct a fire watch while the condition exists.
Chapter 1: Fire Protection Fundamentals
PASSIVE FIRE PROTECTION Passive fire protection refers to fire separation, compartmentalization, structural stability, and a safe means of escape. �ese are all aspects of fire protection that are built into a building from the very beginning of design. For example, the construction and locations of walls and doors could easily be overlooked when fire protection systems are being discussed, but they are critical to the protection of life and property in the built environment. Fire-Rated Barriers Fire-rated walls and doors are designed to contain the spread of smoke and fire. �ese walls and doors are barriers used to create separations that protect an area of a building that is free from smoke and fire from an area that is not. �ese fire-resistive barriers can be used to compartmentalize a building to prevent the migration of smoke and fire to areas outside of the building section where the fire began. �ese building components and the resultant separations are rated in numbers of hours, usually between 30 minutes and four hours. �is rating is based on how long the building component can maintain its integrity during a specific fire that increases in severity with time based on a specific standard. It is important to understand that this rating does not guarantee an integrity time for the building component during any fire that building component may encounter for the time period stated by its rating. If a building component is exposed to a more severe fire, then the component may fail sooner. Structural Stability Structural stability is also an important part of passive fire protection. �e structural design of a building is required to account for the weight of the structure and the building�s contents, but a safety factor or other methods need to be incorporated into the design to ensure that the structure does not lose its ability to support the building in the case of a fire. As an unprotected steel structure is heated in a fire, it can fail and cause a building to collapse. Wood and concrete structures can also fail due to exposure to fire. �e ways in which these materials react to fire differ, but the result of their failures can be catastrophic. �us, the methods employed to prevent or slow the failure of a building�s structure are very important aspects of fire protection. Direct Means of Egress �e shape and layout of a building are also related to passive fire protection. Codes are very specific about the maximum distances an occupant must travel to reach an exit. �ese exit paths must meet specific requirements that oen incorporate the use of the above-mentioned fire-resistive barriers. Paths of travel must be unobstructed, of a certain width, and provided with emergency lighting. �e direction an occupant must travel to reach an exit must be clearly identified. �e number and size of exits provided in a building are required to be adequate to accommodate all building occupants during evacuation. For passive fire protection systems to function as designed, it is important that their importance is recognized and their use is understood. Exits and exit paths function only when they are free from obstructions. Navigating an escape route can be difficult in a fire, but it is significantly easier when an occupant is familiar with the route and has practiced fire drills. Compartmentalization and fire separations function only when doors are closed. Propping a door open will cause the fire barrier to fail and can increase the resultant damage due to smoke and fire.
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DETECTION AND NOTIFICATION Fire detection and occupant notification are a critical part of fire protection. �ey minimize a fire event�s impact on life and property by reducing occupant evacuation and firefighter response times. Timely evacuation is aided by local notification of the fire alarm system, commonly provided by horns and strobes, and early suppression is made possible by direct notification of the municipal fire department or by communication with remote monitoring stations. �e requirements for facility fire alarm systems vary based on the applicable building code, but most installations are based on the National Fire Alarm and Signaling Code (NFPA 72). Fire detection most commonly is accomplished via the detection of smoke, but fire can also be detected by other means such as heat or optical characteristics. Today�s fire detection technologies offer a large number of options that must be properly matched to the detection system�s requirements, the environment in which the devices will be installed, and the type of fire to detect. Notification occurs aer a fire is detected or some other alarm-initiating e vent happens, such as the actuation of a manual pull station or sprinkler water flow switch. When a fire alarm system goes into alarm, the sounding of horns and flashing of strobes is not the full extent of the system�s capabilities. Mass notification systems utilize pre-recorded voice messages to instruct occupants, and notification can also be accomplished through the use of text messaging and email. Fire alarm systems can also interact and control many building system upon alarm, such as elevators, smoke or fire barrier doors, and HVAC systems. In industrial occupancies, fire alarm systems can initiate the shutdown of process equipment. �e capabilities of fire alarm systems have been steadily evolving, and with increased capabilities and the resultant functionality and integration, it is very important that system reliability and proper function are field verified and commissioned. SUPPRESSION SYSTEMS Fire suppression systems are engineered and designed specifically for each individual installation to protect a specified occupancy and/or property from a fire of a particular size and type. �e required design and associated calculations are based on an anticipated worst-case fire, oen referred to as the design fire. Systems are typically designed to suppress only one fire at a time. Systems typically consist of an extinguishing agent (water or chemical, liquid or gas) oen stored in a tank or provided with a connection to a large source of that agent, a network of distribution piping, fittings, valves, and discharge nozzles . Design calculations determine nozzle quantity, placement, flow rate, and pressure and the total system quantity of the extinguishing agent required for suppression. �e pipe, fitting, and valve arrangements are critical aspects of fire suppression system design that affect these calculations. Some fire suppression systems, however, are pre-engineered and do not require design and calculation for each specific installation as long as the system�s guidelines are followed and the system�s parameters are not exceeded. �ese pre-engineered systems are common for kitchen hood fire suppression, but they can be found in other applications as well. To design an adequate fire suppression system, the designer must know what is required to protect the particular occupancy type. �is is based on the expected design fire and the severity of the hazard. For use in the design of automatic sprinkler systems, NFPA
Chapter 1: Fire Protection Fundamentals
13 lists occupancies in generalized hazard class categories based on the magnitude of the expected fire severity. �e designation of a particular occupancy to a specific hazard class is a generalization that can be used as a guideline, but every property should be evaluated based on its own design fire�s potential. NFPA 13�s hazard classifications are based on an occupancy�s quantity of combustible material and its design fire�s heat release rate. More severe hazard classes signify more challenging design fires and, therefore, more robust suppression systems. Assigning the correct hazard class to a property is important because if the hazard potential is underestimated, the suppression system may not be able to contain a fire of a severity greater than the one for which it was designed.
Development of the Life Safety Code In the first decade of the 20th century, no technical committee was exclusively geared toward life-safety concerns. �e Triangle Shirtwaist fire on March 25, 1911 changed that and helped in the development of today�s Life Safety Code (NFPA 101). One of the largest clothing manufacturing companies in New York City, the Triangle Shirtwaist Company was located on the eighth, ninth, and tenth floors of the Asch Building. �e company had more than 500 employees, many of whom were young women and immigrants, who worked long hours in dirty, cramped conditions. �e building itself was a firetrap. It was constructed nearly completely of wood, which was unusual for a building as tall as it was. Instead of three stairways as required by city codes, the building had only two, as the architect had argued that the fire escape outside the building could suffice as the third stairway. �e fire escape, however, went only as far as the second floor. �e doors to the exits opened in toward the rooms instead of outward because the stairway�s landing was only a stair�s width from the door. Also, egress routes were narrow and full of obstacles, and partitions were placed in front of elevators and doors. Finally, the Triangle�s housekeeping contributed to the fire. Rags from cutaway cloth materials frequently piled up on the floors and in storage bins. At the time of the fire, the rag bins had not been emptied in two months. Just before quitting time on March 25, 1911, a worker noticed smoke coming f rom one of the rag bins. In the clothing industry, a fire of this nature was not unusual, but this fire spread rapidly, overcoming employees who tried to put out the fire with buckets of water. Workers on the eighth floor rushed for the exits. One exit was locked, a company policy during working hours. Once it was unlocked, panic ensued, causing a logjam of people in the stairway. Other workers frantically ran for the elevators, but the elevators had been summoned to the tenth floor, where the executive offices were located. When the ele vators arrived, they were crammed with people. �e elevators made so many trips in an effort to save workers on the eighth and tenth floors that the operators were finally overcome by smoke and exhaustion. Some workers climbed out onto the fire escape. One person fell down the fire escape to the courtyard below. Others climbed down to the sixth floor and then went down the stairs to the street. Approximately 260 workers were on the ninth floor, which was congested with long sewing tables that ran along the length of the floor. �e only way to exit the floor was to walk all the way to one end, negotiating around chairs and baskets. When the quitting bell rang, the first worker out walked down the stairs to go home. When he reached the eighth floor, he noticed smoke and flames. He continued on a short distance and then realized
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that he must warn the others on the ninth floor. By then, however, it was too late. �e stairs leading back to the ninth floor were consumed in flames. �e ninth-floor workers discovered the fire when it entered the windows from the floor below. About 150 workers raced for the remaining stairway, and about 100 made it to the street. Others ran for the fire escape. Jammed with people and hot from the fire, the fire escape pulled away from the building, sending many people to their deaths. Many others rushed for the elevators, but they were full. Some jumped or were pushed into the elevator sha. A few slid down the elevator cables. �e fire department arrived in a timely manner, but could do little because its equipment only reached the seventh floor. A total of 147 people lost their lives in the fire.
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Basic Chemistry and Physics of Fire
2
A fire is a chemical reaction involving fuel, oxygen, and heat. �ese elements form what is called the fire triangle (see Chapter 6). Chemical reactions can be either endothermic, a reaction that consumes heat during the process, or exothermic, a reaction that releases heat during the process. Heat is the energy that is absorbed or emitted when a given chemical reaction occurs. In the case of fire, energy in the form of heat is required to begin the reaction, and then aer the reaction is started, heat is released. In other words, combustion begins as an endothermic reaction and then continues as an exothermic reaction. In the case of an explosion, the combustion reaction proceeds rapidly. Most combustibles, such as solid organic materials, flammable liquids, and gases, contain a large percentage of carbon (C) and hydrogen (H). �e most common oxidizing material is the oxygen (O 2) found in air. Air is composed of oxygen (approximately 20 percent), nitrogen (approximately 80 percent), and traces of other elements. In general, any material containing carbon and hydrogen can be combined with oxygen, or oxidized. Usually, both fuel and oxygen molecules must be brought together and then activated before a fire is produced. �is activation can be caused by: u A spark from a nearby fire or from electrical equipment u High friction between two hard surfaces rubbing together, which in turn elevates the material�s temperature u Intense heat, which creates the possibility of the material reaching its flash point (see the Flammable and Combustible Liquids Code, published by the National Fire Protection Association [NFPA]) Once the fuel and oxygen are combined and activated, a chemical chain reaction starts, which causes fire to develop. Heat, smoke, and gases are continuously produced during this process. Once the fire begins, it will continue to burn as long as fuel, oxygen, and heat are present. Other elements that may affect a fire include the following: u A catalyst: A substance that when added or taken away may affect the rate of the chemical reaction, while the substance itself is not changed u Inhibitors or stabilizers: Substances that hinder the mixing of fuel and oxygen u Contaminants: Substances that, if present, may or may not influence the reaction
SMOKE Combustion produces smoke, gases, and heat, which form what is called the fire signature. �e fire signature is never the same for two fires. Smoke, gases, and heat can produce drastic changes in the environment and be hazardous to humans. Statistics show that when a fire occurs, about 60 percent of human casualties are due to smoke and toxic gas inhalation.
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�is may be due to confusion, since people reaching a smoke-filled area on the way to an escape route will normally turn back rather than go through the area to safety. NFPA 92: Standard for Smoke Control Systems is a very good source of information on smoke. According to NFPA, smoke is �the airborne solid and liquid particulates and gases evolved when a material undergoes pyrolysis or combustion, together with the quantity of air that is entrained or otherwise mixed into the mass.� �ese airborne particulates are lightweight, and they rise and spread by air movement. �e amount of smoke produced when a fire burns depends on the mass of air or gas drawn into the fire, which, in turn, is based on the type of combustible. �e amount of air is based on the pressure difference between the fire area and the adjacent space.
Smoke Control In the early 1970s it became evident that, in the design of multistory buildings, smoke control should be included as part of the life-safety systems. In all buildings, buoyancy and the stack effect cause smoke to travel upward; however, smoke movement differs between short buildings and tall buildings. In a short building, the influences of heat convective movement and gas pressure are major factors in smoke movement. In tall buildings, the stack effect drastically modifies the same factors due to the strong dra from the ground floor to the roof due to the difference in temperature. Computerized smoke-control models have been developed to assess and/or control smoke movement in a building. �ese models can simulate the expected behavior of smoke in a multilevel building. Variables such as the outside air temperature, wind speed, building height, air leakage (in and out), building configuration, stack effect, thermal expansion, air supply, and air exhaust can all be programmed into a computer-simulated scenario. �is modeling is useful in planning and assessing building design and performance. A trend in smoke control in buildings is to create smoke-free areas, such as a building�s egress or stairwells. Stairwell pressurization is an accepted way to prevent smoke from seeping into stairwell enclosures. However, care must be taken to not create too much overpressure, which can make access into the stairwell through doors nearly impossible. For this reason, doors are designed to open out of rather than into a stairwell. �e stack effect and air movement are also factors in creating a smoke-free stairwell. Ducting air into the stairwell at different levels is desirable to prevent uneven pressurization. Another method of smoke control involves the pressurization capability of the floors above and below the space where a fire occurs. �is air-pressurized barrier prevents smoke from infiltrating the adjacent floors by producing a higher pressure than the floor in which the fire and smoke developed. Such an arrangement can be programmed into the air-conditioning system as a fire emergency mode. MATERIAL COMBUSTIBILITY Fire protection professionals must have some knowledge of chemistry to estimate the combustibility of the materials in an area as well as the heat and smoke expected to develop during a fire. �e combustibility of a material really means its capacity to burn. Combustible materials oen present themselves in the form of gases, liquids, and solids. Simple organic materials include common fuels, which are also the building blocks of more complex fuels. For example, organic liquids like solvents and hydraulic fluids are all highly combustible. Common combustibles encountered in everyday activity include the following:
Chapter 2: Basic Chemistry and Physics of Fire u
Wood and all wood products u Textiles and all textile materials u Cushioning, man-made foam, and other applicable synthetic materials u Finishes such as paints, stains, and lacquers u Flammable liquids and gases u Plastic materials A noncombustible material as defined by NFPA is �a material, in the form in which it is used, and under the conditions anticipated, that will not ignite, burn, support combustion, or release flammable vapors when subjected to fire or heat.� NFPA 220: Standard on Types of Building Construction also contains the requirements for a material to be considered limited combustible. As previously stated, the principal constituents of combustible materials are carbon (C) and hydrogen (H+). Combustible organic solids are classified as either hydrocarbons, with the chemical compounds CH and CH2 as a base, or others like cellulose and its compounds, which contain the chemical group CH (OH). When these materials burn, the resulting products are carbon dioxide (CO 2) and water (H2O). If any of these combustible organic materials is present when a fire occurs, the flames propagate quickly (at a rate of a few feet per second).
FIRE EXTINGUISHING When attempting to control a fire, the aim is to break the chemical reaction or the continuous combination of fuel and oxygen. Another goal is to reduce one of its products: heat. Since fire is an exothermic reaction, one way to extinguish a fire is by cooling. �e oldest and most universally known fire extinguishing agent is water. Water works as an extinguishing agent because it: u Absorbs heat—1 gallon per minute (gpm) at 60°F can absorb 1,000 British thermal unit per hour (Btuh). u Can extinguish a fire in a closed area at a rate of 1 gpm to a volume of 100 cubic feet. u Vaporizes at 500°F and expands 2,500:1 at this temperature. u Is more effective when mixed with thinning agents, becoming what is referred to as wet water. u Reduces the heat generated by a fire. Other ways to extinguish a fire or control the chemical reaction are to: u Remove the fuel. u Reduce or eliminate the oxygen available for combustion by introducing an inert gas such as nitrogen (N) or, in small fires, cover the fire with a blanket. u Apply chemical extinguishers such as carbon dioxide, sodium, or potassium bicarbonate (or other dry chemicals). To prevent the occurrence and/or spread of a fire, the designer should use methods to reduce the combustibility of various materials. �ese methods may include (for unoccupied areas) creating an inert atmosphere or using fire-retardant materials. However, many materials contain oxidizing agents, which will provide oxygen for combustion even in an inert atmosphere, so be aware of their presence. �e fire-retardant or flame-resistant treatment of otherwise combustible materials helps protect against fire. �is type of treatment for textile or wooden materials substitutes or impregnates the material with a noncombustible (or less combustible) substance. �e process
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can be accomplished through either an absorption or a saturation process. Impregnation can be done in a vacuum, in which case it is called pressure impregnation.
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Fire Safety in Building Design
3
Fire safety must be incorporated early in the design of a building, and the applicable building codes and National Fire Protection Association (NFPA) standards should be consulted and the requirements strictly followed. One important element is the fire resistance of a building, which is detailed in NFPA 220: Standard on Types of Building Construction. �e fire-resistance rating is the time that materials or assemblies can withstand exposure to fire based on the tests prescribed by NFPA 220. All architectural and engineering disciplines involved in the design of a building are responsible for various aspects of fire protection, such as the following: u Determining the location, number, and construction of normal and emergency exits (architect) u Designing emergency lighting, fire alarm systems, and grounding, and specifying sparkproof equipment in hazardous locations (electrical engineer) u Determining the operation mode of the air-conditioning and/or ventilation equipment in fire situations (mechanical engineer) u Protecting the building�s support beams and columns against high heat, performing structural calculations, and selecting protective materials (structural engineer)
EXITS AND OPENINGS During the design stage of a building, special attention is given to the protection of exits, including stairways, corridors, and exit doors. All stairs and other exits in a building should be arranged to clearly point in the direction of egress toward the street. Exit stairs that continue beyond the floor of discharge to the street should be interrupted at the floor of discharge by partitions, doors, or other effective means. Building openings and penetrations are usually designed to help stop the spread of fire and smoke while containing gaseous, total-flooding fire extinguishing systems. If a gaseous agent is used, then strategically located relief vents must be provided for the air displaced by the fire suppression agent when it is released. FIRE BARRIERS To contain a fire in a certain area, a building includes passive restraints, or fire barriers, such as fire walls, fire-resistant floors, and fire-rated doors. Areas that may be more prone to fire, such as control rooms, computer rooms, and repair and maintenance shops, must be constructed of noncombustible materials. �e walls, floors, and ceilings in these areas must also be designed with a fire rating per code requirements. For example, if a door must contain a glass opening larger than 100 square inches, a specific fire door rating will apply. From a fire and smoke protection point of view, doors are designed and constructed based on the degree of protection they provide, such as:
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Non-fire-rated doors, such as the type used in a one- or two-family dwelling that provide limited protection when closed u Fire-rated doors tested to withstand fire for a defined period u Smoke-stop doors made of lighter construction, which provide a barrier to the spread of smoke For industrial construction, automatic fire doors in walls must be used to cut off the following areas: u Boiler rooms u Emergency or standby diesel-generator rooms u Oil-storage rooms u Storage rooms for combustible materials u Flammable, oil-filled circuit breakers, switches, or transformers within a station u Fuel oil pump and heater rooms u Diesel fire pump rooms
FIRE SAFETY PERSONNEL Fire prevention involves a personnel network dedicated to enforcing codes and continuously educating the general public. Engineers, technicians, contractors, and firefighters design, install, maintain, and operate fire protection and fire suppression equipment and systems. Every industry has its own specific fire hazards and its own danger points, but specially trained personnel help apply the right protection for the specific hazard. However, trained professionals are not the only people responsible for fire safety in a building. Building owners should include fire suppression systems in their properties and develop fire prevention programs to fit their specific needs. Occupants should become familiar with and practice the life-saving features. In large organizations, an individual or team is typically responsible for safety, which includes fire prevention. Such organizations should have a fire loss-prevention and control manager dedicated to personnel safety and fire prevention. NEW CONSTRUCTION In the preliminary stages of building construction, a greater danger of fire exists because permanent suppression means are not yet in place. �us, the following basic fire protection recommendations should be implemented: u Provide a temporary water supply source (excluding salt, tidal, or brackish water) for fire protection during the initial construction period in the amount, pressure, and residual pressure required by the authority having jurisdiction (AHJ). Backflow prevention per the water authority�s requirements must be provided for the temporary connection. As construction progresses, a permanent water supply must be made available as soon as possible, and all temporary fire protection water connections should be disconnected from the permanent supply. u Underground mains should be made available as soon as practical, and temporary sprinklers should be installed and used until the permanent system is installed and charged. u As construction progresses, standpipes should be brought up and maintained to be ready for firefighting use. For high-rise buildings, firefighting personnel prefer to have a standpipe (wet or dry) ready for operation, if needed, two floors below the highest floor that is ready.
Chapter 3: Fire Safety in Building Design u
�e use of open flames and welding/cutting equipment should be properly supervised. �e observation or supervision of such operations should be continued for 30 minutes aer the work is completed. For such operations, temporary permits are usually required from the fire department. u Weather shelters and dust covers should be flame resistant. u Facilities for hydrant operation should be made available as soon as possible, and emergency protection in the form of portable extinguishers and hose streams must be provided. In certain cases, a watchperson and standby firefighting apparatus are recommended. u Combustible materials should be kept at a minimum. Form work, shoring, bracing, scaffolding, etc., should be made of mostly noncombustible materials, and the construction site should be kept clean and orderly. Contractors� sheds should be constructed of limited-combustible materials or kept outside the confines of new construction. u On rock sites (when blazing for fire protection lines), installation should be p erformed simultaneously with general excavation to prevent damaging newly placed concrete. u Portable fire extinguishers should be made available within 100 feet of any work area and within 30 feet of welding, burning, or other heat-producing equipment. In summary, when new construction is concerned, it is always smart to: u Assign the overall fire prevention/protection to a responsible person. u Expedite the installation of firefighting systems. u Dispose of construction waste promptly. u Store combustibles in enclosed, ventilated, and easy-to-supervise areas. u Closely supervise temporary heaters. u Provide temporary fire suppression equipment (e.g., mobile hose stations and portable extinguishers). u Carefully handle flammable liquids and gases. u Establish enclosed, controlled areas for smoking. u Take special precautions during welding and other operations involving open flame.
REMODELING During building alteration or remodeling, the sprinkler system should be reconnected or installed at an early stage and kept operational. If work is done on a certain section of the system, that section should be isolated while the rest of the fire suppression system is kept operational. If the entire system is out of order, then standby fire apparatus and/or a watchperson may be employed per recommendations from the fire department or the AHJ. Aer the system is repaired, refurbished, or modified, it must be re-inspected and retested before the installation is considered complete. In case a sprinkler system is rearranged (with no occupancy change) and sprinkler heads must be replaced, they should match the existing sprinklers� style, orifice diameter, temperature rating, coating (if any), and deflector type. All of these replacement criteria are true except if the occupancy and/or the type of inside construction (e.g., ceilings removed or added) changes.
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Commissioning, Testing, and Maintenance
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�e procedures for fire suppression system commissioning are outlined in National Fire Protection Association (NFPA) 3: Recommended Practice for Commissioning of Fire Protection and Life-Safety Systems. NFPA 4: Standard for Integrated Fire Protection and Life-Safety System Testing contains testing procedures for fire protection and life-safety systems. According to NFPA 3, commissioning (Cx) is �a systematic process that provides documented confirmation that specific and interconnected fire and life-safety systems function according to the intended design criteria set forth in the project documents and satisfy the owner�s operational needs, including compliance requirements of any applicable laws, regulations, codes, and standards requiring fire and life-safety systems.� Integrated testing and commissioning are sometimes confused and used interchangeably, but they are not the same thing, which is why two separate NFPA standards were developed. Integrated testing is a vital part of the entire commissioning process. It is used to verify that a building�s fire and life-safety systems perform and interact as designed.
FIRE PROTECTION SYSTEM COMMISSIONING According to NFPA 3, fire system commissioning has the following objectives: documenting the owner�s project requirements (OPR) and the basis of design (BOD), verifying that equipment and systems were installed and perform as required, confirming that integrated testing of fire and life-safety systems was performed, delivering operation and maintenance manuals, training facility staff, and setting up a system for ongoing maintenance and testing. All active and passive fire protection and life-safety systems included in a project must be commissioned, including fixed fire suppression systems and their supporting infrastructure, control systems, fire and smoke alarm systems, emergency communications systems, elevator systems, fire extinguishers, means of egress, through-penetration fire stops, fire walls, barriers, and partitions, and smoke barriers and partitions. Commissioning Team �e commissioning team can be comprised of any of the following individuals: u Owner and owner�s technical support personnel u Commissioning authority (CxA) u Fire commissioning agent (FCxA) u Installation contractors u Manufacturer representatives u Registered design professionals (RDP) u Construction manager/general contractor u Facility manager or operations personnel
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Insurance representative u �ird-party testing entity u Authorities having jurisdiction (AHJ) u Integrated testing agent (ITA) Commissioning Authority �e CxA is the leader of the overall project commissioning team and is responsible for planning, organizing, and facilitating the commissioning process on behalf of the owner. In addition to having good technical knowledge of the systems being commissioned, the CxA must also have a complete understanding of the commissioning process and possess the organizational, documentation, communication, and team-building skills that are necessary to lead and coordinate an effective commissioning team and to ensure that the intent of the building owner is achieved. Fire Commissioning Agent �e FCxA is the team leader in the fire protection system commissioning portion of a project. �is individual develops the commissioning plan, schedules and verifies process requirements, prepares documentation and reports, witnesses and documents testing, tracks compliance, and recommends system acceptance, among other responsibilities. �e FCxA should be knowledgeable and experienced in both the commissioning process and fire protection system design. A qualified FCxA should have an advanced understanding of the installation, operation, and maintenance of all fire protection and life-safety systems to be installed, with particular emphasis on integrated system testing. �is individual is a representative of the owner and as such should be objective and unbiased and should not have any financial interest in any of the systems being commissioned. Registered Design Professional A qualified RDP should have a comprehensive knowledge of the design, installation, operation, and maintenance of all of the systems proposed to be installed and how individual and integrated systems operate during a fire or other emergency. Integrated Testing Agent �e ITA should be knowledgeable in the design, installation, operation, and maintenance of the types of fire protection and life-safety systems to be installed as well as have experience in performance verification methods to validate the functionality of integrated systems and components.
Documentation Documentation of every step of the commissioning process is extremely critical to the overall success of the project. As each decision is made, documentation provides a basis for evaluation and acceptance before proceeding to the next step in the process. Critical documents include the owner�s project requirements, basis of design, commissioning plan, and final commissioning report. Other documents that should be generated during the commissioning process include the commissioning specifications, design review comments, certification documentation, submittal review comments, inspection reports, test data reports, issue and resolution logs and reports, system manuals, and training documentation.
Chapter 4: Commissioning, Testing, and Maintenance
Owner’s Project Requirements Developed by the owner, the OPR defines the expectations, goals, benchmarks, and success criteria for the project. An effective OPR incorporates input from the design team, operation and maintenance staff, and end users of the building and is updated throughout the project. Basis of Design Prepared by the design engineer, the BOD includes design submissions that explain how the proposed design will meet the owner�s project requirements. It describes the engineer�s approach to system selections and integration, focusing on design features critical to overall building performance. Commissioning Plan �e commissioning plan identifies the procedures, methods, and documentation for each phase of the process. It is updated continuously throughout the design, construction, and installation phases, and the completed plan becomes the commissioning record that is given to the owner aer construction. �e commissioning plan should include the following, as applicable to the specific project: u Commissioning scope and specifications u Commissioning team members, including their roles and responsibilities u Communication plan and protocols u Commissioning process tasks and schedules u Required documentation and deliverables u Required testing procedures u Recommended training u Owner�s project requirements u Basis of design u Design and submittal review u Issues log u Construction checklists u Meeting minutes u Functional performance and ongoing testing procedures u System manuals and warranties u Test data reports Final Commissioning Report All commissioning requirements, processes, documents, and findings are incorporated in a final commissioning report that accompanies the construction contractor�s turnover documentation. ASHRAE Guideline 0: e Commissioning Process recommends that the final commissioning report be included with O&M manuals in a systems manual.
Commissioning Process �e fire protection system commissioning process has four phases: planning, design, construction, and occupancy. Planning Phase It is best to begin a commissioning project before design to allow time to develop the plan before anything is installed. �e planning phase accomplishes the following: u Develops the owner�s project requirements u Establishes the team
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Fire Protection Systems u
Identifies the commissioning scope u Develops the commissioning plan Design Phase During the design phase, the basis of design is developed, which should include a description of the project and systems to be commissioned, performance objectives, and testing requirements. �e construction documents should be compared with the BOD and modifications should be made to ensure that the owner�s project requirements are being met. �e commissioning activities schedule should be created and approved, and team members should be assigned specific tasks to accomplish according to the schedule. Construction Phase During construction, the team members should be performing and documenting their tasks as required, and the FCxA should update the plan and schedule when needed. �e construction should be inspected before, during, and aer installation. All systems, both passive and active, shall be tested, and any issues found must be corrected and retested. Occupancy Phase �e occupancy phase includes final system testing, delivering all documentation and reports, training building personnel, and implementing the ongoing inspection, testing, and maintenance program. Aer all of the final modifications have been verified and accepted, the owner takes occupancy of the building and is henceforth responsible for the systems� inspection, testing, and maintenance.
Re-Commissioning and Retro-Commissioning NFPA 3 also addresses re-commissioning—to be performed when an existing system that was previously commissioned is changed—and retro-commissioning—to be performed on an existing system that was never commissioned. �ese processes shall be performed only if the building or system is significantly changed; NFPA 3 does not prescribe an ongoing program of re-commissioning. INTEGRATED TESTING Requirements for the integrated testing of fire and life-safety systems were originally a component of NFPA 3, but they were removed and standardized in a new document, NFPA 4, in 2015. According to NFPA, the new standard �is intended to make sure that buildings with integrated and interconnected systems, such as fire alarms, sprinkler systems, emergency communications systems, elevator systems, standby power systems, and stairway pressurization systems, operate as intended using testing protocols, proper oversight, and verification documentation.� NFPA 4 is intended for both new and existing buildings. �e purpose of integrated testing is to ensure that all fire and life-safety systems work together as intended. NFPA 4 does not include testing or performance requirements for individual systems. �e integrated testing agent is responsible for planning, implementing, and documenting integrated testing. If qualified, the building owner may act as the ITA. Integrated testing should be performed at the end of the commissioning process, when all systems have been installed. While NFPA 4 does not include a timeframe for testing, the ITA should develop a test plan that includes the systems to be tested, documentation, members of the integrated system test team, test scenarios, and test schedules. �e test
Chapter 4: Commissioning, Testing, and Maintenance
plan should include post-occupancy testing requirements based on an assessment of the potential failure of a system. NFPA 4 lists a series of triggers prompting this testing, particularly aer any modifications or additions to the system. While NFPA 4 provides details on test methods and scenarios, the actual testing protocol should be developed by the ITA based on the building�s particular systems.
MAINTENANCE NFPA 25: Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems describes the activities that are required to ensure that fire suppression systems perform as designed when needed. Other NFPA standards for specific types of fire protection systems include requirements as well. Manufacturers also should be consulted for requirements specific to their systems. Ongoing maintenance activities can be divided into the following categories: u Inspecting u Testing u Cleaning u Preventive maintenance u Repair and replacement Inspection Inspection schedules are usually generated by the owner (or owner�s representative) and are based on the manufacturer�s recommendations for the particular equipment. Inspections must be conducted to identify early warning signs of failure. A weekly inspection should be made of any exposed parts, piping, valves, backflow preventers, hangers and supports, etc. It is important to note any leaks, discoloration, rust, or incorrect positions in any of these components. �is inspection should be performed by someone who is trained to know what to observe. Of particular importance are valves, most of which must be in a permanently open position. �e weekly inspection of a fire protection system helps eliminate problems such as blocked fire department connections, vandalized hydrants, leaking pipes and hoses, missing nozzles, permanently open valves that are partially closed, blocked or padlocked emergency exits, and freeze-ups (in the winter). It is also important to inspect the following: u All gauges (monthly) u Priming of water (when required) u Clean, dry system valves (not full of grease and dirt) u System air or nitrogen pressure (weekly) u All control valves, including sealed valves (weekly) and locked valves (monthly) Testing �e person in charge of the system must test it periodically, based on the requirements of NFPA 25, practical experience, and/or manufacturer recommendations, to ensure that the equipment meets specification requirements. All equipment testing must include performance and safety checks. Alarms must be tested on a regular schedule, which must be well publicized to building occupants. Dry pipe systems must be tested annually but mainly before the winter. Table 4-1 illustrates the test and inspection frequency of water-based suppression systems.
21
22
Fire Protection Systems
Table 4-1 Test and Inspection Frequency of Water-Based Suppression Systems Inspection
Frequency
Dry, deluge, and preaction system gauges
Weekly
Wet system gauges
Monthly
Sealed control valves
Weekly
Locked control valves
Monthly
Tamper switch control valves
Monthly
Fire department connections
Quarterly
Water flow alarm devices
Quarterly
Valve supervisory alarm devices
Quarterly
Hydraulic nameplate
Quarterly
Buildings prior to freezing weather
Annually
Hangers, seismic bracing, pipes, and fittings
Annually
Sprinklers, spare sprinklers, information sign
Annually
Check valves, interior
Every 5 years
Internal inspection of piping Test
Every 5 years Frequency
Water flow alarm mechanical devices
Quarterly
Water flow alarm vane and pressure switch type devices
Semiannually
Priming water (dry, deluge, and preaction)
Quarterly
Low air alarm
Quarterly
Main drain (sole water supply through backflow or pressure-reducing valves)
Quarterly
Main drain
Annually
Control valves (position and operation)
Annually
Dry pipe system trip test
Annually
Dry pipe system full flow trip test
Every 3 years
Antifreeze solution
Annually
Gauges tested or recalibrated
Every 5 years
Sprinklers (extra high temperatures or harsh environment)
Every 5 years
Sprinklers, dry
Every 10 years
Sprinklers, fast response Maintenance
Every 20 years Frequency
Low-point drains in dry pipe systems (after each operation of the system, before the onset of freezing weather)
As needed
Sprinklers and automatic spray nozzles
Annually
Valves, valve components, and trim (additional maintenance as required by the manufacturer’s instructions)
As needed
Cleaning A scheduled cleaning program is required. Maintenance personnel must perform basic cleaning duties for each system on a regular basis. All parts of the fire protection system must be kept clean and free of debris. Preventive Maintenance All fire protection equipment must be scheduled for preventive maintenance based on regular inspection results and a scheduled preventive maintenance program. Repair and Replacement As a system ages, the need for repair and perhaps equipment replacement becomes more prevalent. It is necessary to maintain spare parts and provide for their storage.
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Fire Detection Systems
5
A fire protection system consists of prevention, suppression, notification, auxiliary control, detection, annunciation, and communication reporting systems. �e detection and communication reporting systems include the following: u A manual means of sensing the products of a fire u Automatic detectors that sense the products of a fire, harmful gases, or the flowing of water or dispersal of suppression agents u Notification appliance circuits and notification appliances u Local and remote annunciation for the fire alarm system u A means of controlling auxiliary life-safety and non-life-safety systems u Communication systems that activate active fire suppression and containment systems u Communication reporting systems that report to on-premise or off-premise emergency response centers for fire department dispatching Unlike sprinkler or suppression systems, detection devices do not control or extinguish a fire—they merely detect the products of fire combustion or deadly gases such as carbon monoxide or chlorine. However, detection systems are a critical aspect of fire suppression systems because they provide notification of a developing fire early enough to allow for the greatest available safe egress time (ASET). A balanced approach of early fire detection and suppression control offers the best possible outcome toward achieving the goal of protecting the lives of the occupants within the building.
CARBON MONOXIDE DETECTION State and local building codes are adopting mandatory detection requirements for carbon monoxide at a rapid pace. �us, fire detection system designers need to be aware of these requirements and change their approach to identifying not only what is needed for fire detection, but also carbon monoxide and other harmful gas detection as well. Because plumbing system designers oen design and specify fuel-fired water heating equipment and water purification systems that utilize halogenated gases and compounds, it is important to be knowledgeable about carbon monoxide detectors and chlorine, ammonia, and other gas detectors that can be connected to a fire alarm system. It is good practice to coordinate systems with the professionals responsible for the fire alarm system to let them know of a need for carbon monoxide or other harmful gas detectors and where in the building they may be required. �e National Fire Protection Association (NFPA) has published additional secondary power supply requirements for fire alarm systems with carbon monoxide detectors in NFPA 72: National Fire Alarm and Signaling Code and NFPA 720: Standard for the Installation of Carbon Monoxide (CO) Detection and Warning Equipment . Along with these additional power requirements come alarm reporting requirements and separate, distinct evac uation
24
Fire Protection Systems
signaling requirements for carbon monoxide sensors. �e details of these requirements are outside the scope of this chapter, but the plumbing system designer must coordinate with the design team to ensure that the proper detection devices are installed.
BASIC COMPONENTS OF A FIRE ALARM SYSTEM Some of the questions that must be answered before designing a fire alarm system are: u What type of detection is required� u Is automatic smoke detection required� u Is a high-rise voice evacuation signaling system needed� u Is auxiliary control of stairwell pressurization required� u Is circuit pathway survivability needed for a defend-in-place strategy� A fire alarm detection and signaling system contains the following components: u A control panel with operator interface and primary and secondary power supplies, as well as communication and reporting circuits, signaling line circuits (SLC) for addressable components (intelligent and analog-type sensors), initiating device circuits (IDC) for conventional detection devices (hardwired, non-intelligent type), and a notification appliance circuit (NAC) for horn-strobe or speaker and strobe appliances for evacuation signaling u A remote annunciator control panel with communication and reporting circuits u Auxiliary power to supply additional power and secondary power for NAC circuits or for auxiliary power to primary components of the fire alarm system that are not powered by the main control panel u Heat detectors, which can be either the intelligent analog addressable or the conventional hardwired type u Smoke detectors u Manual fire alarm boxes, also referred to as pull stations u Water flow detectors, commonly referred to as flow switches on a sprinkler system u Notification appliances such as electric horns and strobes u Auxiliary control for both life-safety and non-life safety functions, such as air handler shutdown, egress door unlocking, and elevator recall A detection system must be properly designed and the detectors must be carefully selected for the types of fire and non-fire hazards (i.e., harmful gases) and the resulting products expected, which depend on the combustible materials, operational activities within the area, and environmental factors of the protected space. Even though detectors do not directly affect a fire, they may be connected to initiate other functions, including: u Sounding a local and/or remote alarm that notifies building occupants of a fire situation u Isolating an area by closing dampers and doors u Either shutting down the operating ventilation equipment or starting smoke evac uation fans and opening fresh-air dampers or doors u Supervising the system for ready-for-operation status u Activating fire suppression systems Detectors in most types of buildings are electrically connected through communications circuits (pathways) to a main fire alarm control panel (FACP). Detectors in high-rise buildings or industrial complexes may also be connected via a communications pathway from the FACP to a remote fire alarm annunciator panel (FAAP). Control panels are oen
Chapter 5: Fire Detection Systems
located in a fire-rated control room, which is intended to be continuously attended. If the building does not have continuous 24-hour supervision in a given location, the authority having jurisdiction (AHJ) may insist that a remote annunciator panel be located at the first point of entry for the emergency responders, such as a main lobby entrance or a fire sprinkler riser room. �e control and annunciator panels may also receive trouble signals that indicate such things as a fault in the supervisory system, a component being in the wrong position, a depleted secondary power supply battery condition, or some other condition in need of maintenance and correction.
MANUAL VS. AUTOMATIC DETECTION SYSTEMS A fire detection system can be either manual or automatic. A manual system relies on a person to observe fire and/or smoke and pull an alarm to alert occupants. �e person may also activate a suppression system. An automatic system relies on a detector to sense products of combustion and activate an alarm or fire suppression system and other auxiliary systems (smoke evacuation, etc.). Automatic detection can be accomplished with electronic smoke detection, radiant energy detection, or electronic heat detection, but it is important to note that automatic detection is also defined in model building codes and NFPA standards as the detection of water flow from a fire sprinkler or suppression system that must be installed and continuously monitored as required by NFPA 13: Standard for the Installation of Sprinkler Systems and NFPA 72. It is up to the designer to recognize this and any additional requirements for automatic fire detection that involves applications in addition to water flow detection. An automatic detection system notifies building occupants of a fire or a near-fire condition and summons an organized response. It may also activate a fire suppression system, supervise the protection system, and detect any signs of a change of status as well as restoration to a non-fire condition. Before installing an automatic detection system, it is first necessary to establish whether or not it is needed. Local codes or regulations may provide guidance for this decision. Some factors to consider are: u Importance of the area (types of contents and their value) u Degree of fire hazard within the area u Potential of fire spreading u Type of fire suppression u Normal occupancy of the area u Cost of detection and/or suppression systems u Installation of detection and suppression or just detection Once a decision is made to install an automatic detection system, it is necessary to establish the detection requirements for the area and then select the appropriate detector types and place them in the correct locations and at the correct distances from one another. TYPES OF DETECTION DEVICES �e four basic types of detectors are heat detectors, smoke/gas detectors, flame detectors, and water flow detectors. Heat Detectors Heat detectors sense the heat produced by burning combustibles. �ey are the oldest and least expensive automatic detectors available. �ey also have the lowest rate of false alarms.
25
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Fire Protection Systems
However, they are fairly slow in detecting a fire in its initial stage and are better suited for small, confined spaces where high heat is expected. Heat detectors also do not detect the early products of combustion like automatic smoke detectors and radiant energy sensors. Understanding these limitations is paramount to designing an appropriate life-safety system. Heat detectors can be either spot detectors, which are concentrated at a particular location, or continuous-line detectors, which are used mostly for cable trays and conveyors. �e three types of heat detectors are based on the way they operate: fixed temperature, rate compensation, and rate of rise. Fixed-Temperature Heat Detectors As a spot detector, the fixed-temperature heat detector consists of two metals (each having a different coefficient of thermal expansion) that are bonded together. When heated, one metal will bend toward the one that expands at a slower rate, causing an electrical contact to close. �is type of detector is very accurate and is set for various temperatures that can be expected to develop during a fire. It is also automatically self-restoring, which means that aer the operation is complete, the detector returns to its original shape or condition. �e fixed-temperature type of heat detector is analogous to a thermally operated sprinkler head in that it is rated and visually labeled for a specific operating temperature. It is also UL Listed or FM Approved to provide detection coverage for a specific-size area. As a continuous-line detector, the fixed-temperature heat detector can include a pair of steel wires enclosed in a braided sheath to form a single cable (see Figure 5-1). �e two concentric elements are separated by heat-sensitive insulation. Under heat exposure, the insulation melts, and the wires make contact. Since the portion affected must be replaced, this type is not self-restoring. Figure 5-1 Continuous-Line FixedAnother type of continuous-line, Temperature Heat Detector fixed-temperature heat detector includes two coaxial cables with temperature-sensitive semiconductor insulation between them. In cases of high heat, the electrical resistance of the insulation decreases, and more current flows between the wires, causing contact to be initiated. �is type of detection is self-restoring because no insulation melting takes place during the process. Rate-Compensation Type �e rate-compensation heat detector (see Figure 5-2) reacts to the temperature of the surrounding area. When the temperature reaches a predetermined level, regardless of the rate of temperature rise, electrical contact is made. �e difference between a rate-compensated detector Figure 5-2 Rate-Compensation Heat Detector and one with a fixed temperature is that the former eliminates the response at the peak temperature. �e entire detector enclosure (rate compensation) must reach the critical (previously set) temperature and only then does it make contact, sounding an alarm or activating a fire suppression system.
Chapter 5: Fire Detection Systems
Rate-of-Rise Type �e rate-of-rise heat detector (see Figure 5-3) is effective when a rapid rise in temperature is expected due to a fire caused by a specific type of combustible. �is detector sounds an alarm and/or starts a suppression system when the temperature rise is faster than 15 to 25°F per minute. It will compensate for small fluctuations.
27
Figure 5-3 Rate-of-Rise Heat Detector
Smoke Detectors Smoke detectors can be of either the ionization type or the photoelectric type. �e photoelectric type is further divided into light-obscuration and light-scattering types. Ionization Type �e ionization type is very common and uses a small quantity of low-grade radioactive material to ionize the air within the detector and make it electrically conductive. If smoke enters the detector, the smoke particles attach themselves to the ions, and ion mobility is decreased. An alarm then sounds. Photoelectric Type In the photoelectric light-obscuration type (see Figure 5-4), the detector consists of a two-piece metal tube with a light source at one end and a receiving photo cell at the other. Between the light source and the receiver is a light beam. �e rising smoke from a fire obstructs the light norFigure 5-4 Photoelectric Light-Obscuration mally traveling toward the receiving Smoke Detector cell, which then causes the detector to sound an alarm. Special light filters prevent other light sources within the area from influencing the cell. �is type has certain special applications due to the length of the light beam, which is operationally useful for a Figure 5-5 Photoelectric Light-Scattering Smoke distance up to 300 linear feet. Detector �e photoelectric light-scattering type (see Figure 5-5) is similar to the light-obscuration type, except that the light and cell are located within the detector body, and light beams do not normally fall on the receiving cell. �e light beam is scattered, so when the smoke rises, the light beam is redirected toward the receiving cell, which then makes contact.
Flame Detectors Flame detectors respond to radiant energy and respond very quickly to a fire. �ey are oen used in areas where the potential for an explosion exists.
28
Fire Protection Systems
Light is visible to the human eye when its wavelength is between 4,000 and 7,700 angstroms (A). When the wavelength is smaller than 4,000 A, it is ultraviolet light. When the wavelength is greater than 7,700 A, it is infrared light. Both types of light (ultraviolet and infrared) are invisible to the human eye. �e ultraviolet light generated by the sun might produce false alarms, so detectors have been developed to reject sunlight and other unwanted radiation (e.g., from welding). Lenses must be kept clean and free of dust or mist to be responsive and sensitive. One way to keep them clean is to provide an air shield. Compressed air is either blown over the lens, or a mechanism similar to windshield wipers on a car wipes the lens occasionally. Infrared detectors operate best when they are separated from the flame by height and distance. �ey work well in large open areas that contain an accumulation of flammable liquids (e.g., aircra hangars). �e sensing element is either a silicon solar cell or a sulfide cell made of lead or cadmium. A built-in time delay allows the detector to discern a flicker from a continuous infrared light emanating from a fire.
Water Flow Detectors �e paddle-type and pressure-switch types of water flow detectors are electrically connected via communication pathways to the fire alarm system, which continuously monitors them for a change of state to activated or trouble. �ese detectors have physical momentary switches with two electrically isolated, identical sets of electrical terminals that consist of a common terminal (neutral), a normally open terminal, and a normally closed terminal. �e electrical isolation is necessary so a line voltage circuit (typically 120 volts AC) can be routed through one set of terminals for items such as an interior 4-inch water flow alarm or a 10-inch exterior water flow alarm, which can be routed through the switch. Also, a 12-volt or 24-volt DC fire alarm initiating device circuit can be run through the other set of terminals, allowing both supervision and detection of the state of the water flow detector. In most cases, NFPA 13 requires the installation of 4-inch and 10-inch electrically operated bells (when a water motor gong is not used) as well as connection to a fire alarm control system. If an automatic sprinkler system is installed, NFPA 72 requires it to be connected to the automatic fire alarm system to notify building occupants and communicate with an emergency reporting station for alarm and trouble conditions in the sprinkler system. A good practice for any sprinkler or suppression system designer is coordinate the location of these types of devices along with their valve supervisory switches (tamper switches) with the fire protection engineer or alarm technician responsible for the design and layout of the fire alarm system. CHOOSING A DETECTOR DEVICE A detector�s operational characteristics and physical location influence the selection of the detector type and its placement. Following are a few guidelines to consider when selecting a detector: u Combustion products: Certain detectors are sensitive to specific combustibles and no other products. �e detector may only react if the smoke emanating from a material falls within certain parameters. For example, ionization detectors may not detect large smoke particles because they lack high mobility. u Fire development: �e speed of fire development differs from oil fires to electrical fires to other kinds of fires. Some detectors will not detect all types of fire development.
Chapter 5: Fire Detection Systems
29
u
Ventilation: If a large ventilation air rate is normally needed for the area, then the combustion products may be drawn out of the area before they reach the detectors. �is might be the case if the detector is mounted on the ceiling. �e type of detector selected should be installed close to the area protected or close to the air exhaust from the room. �e area surrounding the air supply might actually be kept free of smoke. u Room congestion: Certain detectors have to �see� the fire. A maze of pipes, ducts, vessels, etc., may obstruct the hazard area. u Room geometry: A very high room renders heat, photoelectric, and ionization detectors ineffective. �e best choices for such an application are infrared or ultraviolet detectors. u Operational activities: Check whether the operational activities in the area may produce signals that would involuntarily trigger detector operation. For example, ionization detectors do not distinguish between combustion products from a fire and those from a diesel generator in operation. In a diesel generator room, heat detectors are recommended. u Cost: If a large number of detectors will be installed, the equipment cost plus installation costs could become significant. Selecting the right detector is not an easy task. Experience gained with practice coupled with help from detector manufacturers and consultation with the AHJ can assist in finding the correct solution. Table 5-1 provides a summary of the different detector applications and recommended uses. Table 5-1 Detector Applications Summary Type
Where to Use
Application
Recommended Use
Cost
Large open areas, to protect heat-generating equipment
Responds when a predetermined temperature is reached
Use limited to indoor applications, low false alarm rate, a reliable device
Low
Large open areas
The rate-of-rise response to a specific temperature rise per minute
Should be used indoors, low false alarm rate
Low
Should be used indoors, low false alarm rate
Low
Heat Detectors Fixed temperature
Rate of rise
The detector and its enclosure must reach a critical temperature. It compensates to spikes. Smoke Detectors
Rate compensated
Large open areas, to protect heat-generating equipment
Photoelectric
Projected beam type used in open areas, high rack storage, computer rooms, and aircraft hangars
Smoldering fires
Must be used indoors
Moderate
Ionization
Offices, computer rooms, combustible materials
Fast-flaming fires
Should be indoors
Moderate
Flame Detectors
Infrared
Hazardous work, explosive and rocket propellant manufacturing, aircraft hangars
Rapid response to infrared radiation generated by fire
Indoor use, may be affected by heat
High
Ultraviolet
Hazardous work, explosive and rocket propellant manufacturing, aircraft hangars
Rapid response in milliseconds to ultraviolet radiation generated by fire
May be used indoors or outdoors, lenses need cleaning
High
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Fire Protection Systems
DETECTOR LOCATION AND SPACING �e location and spacing of detectors must be consistent with the environment in which they operate and the qualifications for which they were tested. For example: u Keep heat detectors away from normal heat sources such as space heaters. For spot heat detectors, it is best to install them on the ceiling or side wall (not closer than 4 inches from either). When the ceiling either does not have a smooth surface or is higher than 16 feet, the spacing is based on specific NFPA recommendations as well as the requirements of the AHJ. u Install smoke detectors close to the return air register. �ey should not be installed close to the air supply into the area. u Install flame detectors where they can �see� the fire. EVACUATION SIGNALING (NOTIFICATION APPLIANCE CIRCUITS) Like fire detectors, signals do not fight fires directly. However, by alerting building occupants of a fire situation, signals can save lives and/or property. A fire detection system is normally connected to an alarm system. NFPA 13 requires the installation of local water-flow alarms in areas that have more than 20 sprinkler heads. �is type of signal provides a warning sound and, required in most jurisdictions, a visual signal as well that alerts personnel that water is flowing from one or more sprinkler heads. �e alarm signal may be initiated by an alarm check valve installed in the system�s riser. �is check valve may be connected to a water flow switch or a mechanical device, which activates a gong or bell and has a second circuit connected to the fire alarm system. Evacuation signaling systems are not detailed in this chapter because specialized technicians in the electric/electronic field are responsible for the design and installation of such systems. However, alarm systems are always installed in cooperation with the fire protection engineer who establishes the criteria.
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Fire Suppression Overview
6
In spite of fire prevention methods, controls, and alarms, fires occur and endanger lives and property. For this reason, fire suppression systems are necessary. �ese systems are comprised of various agents and methods and are effective at controlling and potentially extinguishing fires, but whenever a fire starts, firefighters still must be called. �e general strategy when fighting a fire is to locate it, surround it, confine it, and extinguish it. However, when firefighters arrive at the scene of a fire, their first concern is the safety of any occupants who could be trapped. When firefighters attack a fire in a lowheight building, one of their first actions is to punch a hole in the building�s roof so heat and gases may escape. If confined, heat and gases could hamper the firefighters� capabilities and escalate the fire�s development.
EXTINGUISHING AGENTS Fire suppression involves an extinguishing agent and a means, system, or procedure to apply the extinguishing agent at the fire�s location. �e selection of an appropriate extinguishing agent should be based on several factors, including the following: u �e building�s construction materials and contents u �e type of combustible materials known or assumed to be involved in a fire in the protected area Heat Oxygen u �e configuration of the area u Extinguisher expectations and performance u How the extinguisher affects one of the three elements Fuel involved in the fire triangle (see Figure 6-1) Figure 6-1 The Fire Triangle u Cost u �e cleanup required aer the fire is extinguished Table 6-1 shows the classifications of combustible materials that may be involved in a fire and the type of suppression agent recommended. Table 6-1 Classifications of Combustible Materials Class
Combustible Materials
Suppression Systems and Agents
A
Ordinary combustibles such as wood, paper, or anything that leaves ash
Water works best. Carbon dioxide and foam designated as Type A can also be used.
B
Flammable or combustible liquids, including oil, gasoline, and similar
Smothering effects, which deplete the oxygen supply, work best (foam, water spray, carbon dioxide, and dry chemicals).
C
Electrical equipment
Always de-energize the circuit and then use a nonconductive extinguishing agent such as carbon dioxide or a clean agent.
D
Combustible metals, such as magnesium and titanium
Dry powder agents work best by smothering and heat absorption.
K
Cooking oils, grease, or animal fats
Dry powder extinguishing agents work best.
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Fire Protection Systems
One of the goals of a fire suppression system is to affect one of the three elements involved in a fire (oxygen, fuel, and heat). When fighting a fire that is either exposed to the atmosphere or involves an oxidizing agent, the goal is to lower the oxygen concentration below the minimum level (at or below 15 percent for general materials and 8 percent or lower for a smoldering, deep-seated fire in a cable tray) so combustion is not supported. One way to prevent contact between a fire and the oxygen contained in the atmosphere is to apply a layer of inert gas over the fire�s surface in an enclosed space. If an area is unoccupied and can be leak-proofed, inerting the respective room�s atmosphere is another possibility. �e temperature element of a fire may be controlled by cooling the combustion zone. �e temperature should be lowered below the ignition temperature of the fuel vapors. �e most efficient cooling agent utilized in fire suppression is water, which is an extremely efficient heat absorber. Water is also inexpensive when compared to other extinguishing agents and available in most buildings through an existing network of pipes. Water is not dangerous or noxious to humans, and it can be cleaned easily. Fires involving flammable liquids or gases are typically extinguished by cutting off the fuel supply at the source (such as closing a valve, which may be activated by a fusible link).
Water Fixed water systems include hydrants on streets, hose stations or standpipe stations in buildings, and sprinklers in buildings. All of these systems require a reliable source of water and a connecting network of distribution pipes. �e supply of water may come from the city water line or a natural body of water such as a river, lake, or well (freshwater only). Note: In areas with freezing temperatures, man-made reservoirs must be protected and checked daily. A water source must be reliable. It must be available during droughts or freezing temperatures and be able to supply the anticipated amount required as determined by engineering calculations or available standards such as those by the National Fire Protection Association (NFPA). When the water supply source cannot provide enough water flow, storage tanks may be installed to furnish the balance required during firefighting operations. NFPA 22:Standard for Water Tanks for Private Fire Protection provides the standard installation and maintenance details for water tanks in private fire protection systems. �e amount of water stored for fire protection purposes varies with the type of hazard. Calculations take into consideration the standard amount of water stored as well as the flow required and the expected duration of the suppression operation. �ese calculations determine a base storage requirement. From the reservoir, water may be supplied to the extinguishing system by gravity (if the required head or pressure available is adequate) or with the assistance of pumps. �e gravity system may be employed when the water source is located at an elevation high enough to provide the required working pressure at the sprinkler or hose station in the most remote location. When this pressure is not available, pumps are installed to deliver the flow capacity and pressure required for system operation. If the supply system delivers a pressure that is lower than that required, booster pumps are installed. �is type of pump boosts the pressure for proper system operation.
Chapter 6: Fire Suppression Overview
Where dual water sources, chemicals, and/or pumps are needed, check with the water authority for the proper backflow prevention required.
Alternative Suppression Systems Other fire suppression agents are available in addition to water. �ese include the following: u Carbon dioxide (CO2) u Clean agents: HFC-227ea (FM-200), HFC-125 (ECARO-25, FE-25), and FK-5-1-12 (3M Novec 1230) u Inert gases: IG-55 (ProInert, Argonite) and IG-100, IG-541 (Inergen) u Dry and wet chemicals u Foam �ese systems are detailed in later chapters in this manual and the appropriate NFPA standards.
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Fire Pumps
7
In a pressurized water-distribution system for fire protection, the first piece of equipment is the pump, which supplies and distributes water (through a network of pipes in the case of fire protection) from the source (reservoir or city water pipe) to the point of application (see Figure 7-1). For the purposes of this book, a pump is defined as a mechanism that is used to push a liquid with a specific force to overcome friction losses and any existing differences in elevation (static or head losses). �e pump produces this force with the help of a motor or a driver and consumes energy in the process. Fire pumps are part of National Fire Protection Association (NFPA) history. They were mentioned in the first standard issued in 1896, and in 1899 an NFPA committee was organized to study fire pumps. All fire pumps must be listed with UL. �e various types of centrifugal pumps used for fire protection include Figure 7-1 Fire Pump System horizontal split case, inline, end suction, and vertical turbine (see Figure 7-2). Pump capacities range from 25 to 5,000 gallons per minute (gpm), and pressures range from 40 to more than 500 pounds per square inch (psi). Electric motors and diesel drivers (both of which must be UL Listed) may occasionally exceed 500 horsepower (hp). A special feature of a fire pump is the fact that it must deliver 150 percent of the rated capacity at no less than 65 percent of the rated head (pressure). In other words, a 1,000-gpm pump rated at 100 psi must be capable of delivering 1,500 gpm at a minimum of 65 psi. Another special feature is that the shutoff pressure of a fire pump (i.e., at zero capacity) must not exceed 140 percent of the pressure at the rated capacity. Many pumps on the market have a much lower shutoff head than 140 percent. All fire pumps must be used with positive sucFigure 7-2 Vertical tion pressure, and they cannot be used for suction li applications. If Turbine Fire Pump suction li is required, a vertical turbine pump must be used. Source: Patterson Pump Co.
36
Fire Protection Systems
�e capacity of a pump is the rate of fluid flow delivered, which is generally expressed in gallons per minute. �e head (pressure) furnished is the energy per unit weight of the liquid. �e total head developed by a pump is the discharge head minus the suction (inlet) head: Equation 7-1
H = hd – hs where
H = Total head, ft hd = Discharge head, ft hs = Suction inlet head, ft
PUMP COMPONENTS �e pump housing is referred to as the casing, which encloses the impeller and collects the liquid being pumped. Figure 7-3 Impeller Rotation �e liquid enters at the center, or eye, of the impeller (or eyes of the impeller in the case of a horizontal split-case pump). �e impeller rotates, causing centrifugal force to push the liquid out (see Figure 7-3). �e velocity is the greatest at the impeller�s periphery, where the liquid is discharged through a spiral-shaped passage called the volute. �e shape is designed to provide an equal liquid velocity at all circumference points. �e fire pump assembly consists of a pump and a driver. Common drivers for fire pumps are electric motors and diesel engines. Steam turbines, while still in the code, are no longer available on the market. �e maximum speed of listed fire pumps is 3,600 revolutions per minute (rpm). Pumps with double drivers are no longer allowed per NFPA 20: Standard for the Installation of Stationary Pumps for Fire Protection. �e most common driver is the electric-motor squirrel cage, induction type, three phase, in various voltages. Controllers are available for combined manual and automatic operation. Diesel drivers do not depend on outside sources of power (electricity). A diesel driver is similar to a car engine, except that it is stationary and runs on diesel fuel oil (no. 2). A storage tank for no. 2 fuel oil should contain enough fuel for eight hours of continuous pump operation and have a capacity of at least 1 gallon per horsepower plus a 5 percent volume for expansion and a 5 percent volume for sump. (Note: 1 hp equals 0.746 kW, or 3 kW equals approximately 4 hp.) Diesel engine controllers must have an alarm system to indicate: u Low lubricating oil pressure u High coolant temperature in the engine jacket u Failure to start automatically u Shutdown on over-speed u Battery failure u Battery charger failure u Engine running u Controller main switch turned from automatic to manual or off To ensure that the pump will start when required, it should have an optional timer that will start the pump once a week and run it for a predetermined time (usually 30 minutes). A few things to consider with a motor-driven fire pump follow: u �e diesel fuel tank shall be mounted high enough to keep the engine primed.
Chapter 7: Fire Pumps
37
u
�e main control switch shall be automatic. u �e pump shall start automatically in case of a drop in system pressure. u �e pump may be started manually or automatically (for test purposes). Per NFPA 20, the component of the fire pump shall be sized as shown in Table 7-1. Table 7-1 Centrifugal Fire Pump Component Sizing Data Pump Rating, gpm
Suction, in.
Discharge, in.
Relief Valve, in.
Relief Valve Discharge, in.
Meter Device, in.
Number of Hose Valves
Size of Hose Valve, in.
Hose Header Supply, in.
250
3½
3
2
2½
3½
1
2½
3
300
4
4
2½
3½
3½
1
2½
3
400
4
4
3
5
4
2
2½
4
450
5
5
3
5
4
2
2½
4
500
5
5
3
5
5
2
2½
4
750
6
6
4
6
5
3
2½
6
1,000
8
6
4
8
6
4
2½
6
1,250
8
8
6
8
6
6
2½
8
1,500
8
8
6
8
8
6
2½
8
2,000
10
10
6
10
8
6
2½
8
Source: NFPA 20
BOOSTER PUMPS When a fire protection installation is supplied from a low-pressure water source, the sys tem will require a booster pump. �is type of pump raises the pressure in the water supply line. For a relatively small installation, the pressure from the city water source is usually adequate. �e booster pump is selected based on the flow requirements and the pressure difference required. If, for example, the required operating pressure for a fire protection system is 125 psi and the pressure available from the source at rated flow (such as city water) is 50 psi , a booster pump is necessary. To calculate the booster pump size required, find the difference between the required and available pressures, which in this case is 75 psi (125 psi –50 psi). A safety factor of 10 percent should be added to the required pressure, so 125 psi + 12.5 psi (safety factor) – 50 psi = 87.5, or a 90-psi pump head selection. SPARE PUMPS In a large installation, spare pumps may be installed for emergency situations. �e number of pumps to be installed depends on the situation. For example, if the total capacity required is 1,500 gpm, two pumps could be installed, each with 1,500 gpm at 100 percent capacity, with one pump being the spare. Alternatively, it would be possible to install three pumps, each at 50 percent of capacity, or 750 gpm each. All pumps have the same design pressure. �e spare capacity is an added safety, which might be desired or requested by the authority having jurisdiction (AHJ) or the insurance underwriter. Because there is no clear-cut solution to the question of spare pumps, every system must be analyzed independently. �e final decision is usually made among the designer, owner, and AHJ. �e designer should present the owner with the available pump options, including the proposed pump type, number of pumps, initial cost, maintenance requirements, and the installation space required for each alternative. An educated decision can be made only aer a detailed and specific analysis has been performed.
38
Fire Protection Systems
MAINTAINING PRESSURE In addition to a fire pump, a fire protection installation includes a jockey pump or a hydropneumatic tank to maintain a constant, predetermined pressure in the sprinkler system and/ or at the hose stations. A jockey pump may also compensate for minor leaks or a limited test of water discharge from the system. Jockey Pumps �e jockey pump is not a fire pump. It is a small pump with only 10 to 50 gpm capacity, but it has a discharge pressure (head) that is 10 psi higher than the fire pump. It does not have the same special requirements as a fire pump. Each fire pump motor, jockey pump, or engine controller is equipped with a pressure switch or pressure transducer. If the pressure in the system drops to a predetermined level, the jockey pump starts first. If the pressure in the system continues to drop because the flow cannot be satisfied, the fire pump starts. �e fire pump system, when started by a pressure drop, should be arranged as follows: u �e jockey pump�s stop point should be 5 psi lower than the maximum churn pressure of the fire pump. Churn pressure is defined as the pressure produced by a pump at zero flow. u �e jockey pump�s start point should be at least 10 psi less than its stop point. u �e fire pump�s start point should be 10 psi less than the jockey pump�s start point. Use 10-psi increments and time delays for each additional pump. Where minimum run times are provided, the pump will continue to operate aer attaining these pressures. �e final pressures should not exceed the pressure rating of the system. (Note: Some authorities having jurisdiction and insurance underwriters have these times disabled in the field.) For example, a 1,000-gpm, 100-psi pump with a churn pressure of 115 psi is selected. �e suction supply is 50 psi from the city minimum residual and 60 psi from the city maximum static. �us, u Jockey pump stop = 115 + 60 – 5 = 170 psi u Jockey pump start = 170 – 10 = 160 psi u Fire pump stop = 5 psi higher than the start point u Fire pump start = 160 – 10 = 150 psi u Fire pump maximum pressure = 115 + 60 = 175 psi Hydropneumatic Tanks Another way to maintain the water pressure in a sprinkler system is to install a hydropneumatic tank, but this method is not used very oen due to cost. A hydropneumatic tank is pressurized and consists of a small water storage tank (100 to 200 gallons) with a cushion of compressed air in its upper portion (see Figure 7-4). �e volume of air and the tank�s pressure depend on whether the hydropneumatic tank is located above or below the sprinkler heads. If the tank is located above the sprinkler heads, the minimum pressure can Figure 7-4 Hydropneumatic Tank be calculated as follows:
Chapter 7: Fire Pumps
39
Equation 7-2
P=
30 – 15 A
where
P = Air pressure, psi A = Volume of air in the tank (usually 33, 50, or 60 percent)
For example, if A = 0.33 (33 percent), the result is as follows: P = (30/0.33) – 15 = 76 psi
If the tank is located below the sprinkler heads, the minimum pressure can be calculated as follows: Equation 7-3
P=
30 0.434 + H – 15 + A A
where
H = Height of the highest sprinkler head above the tank bottom, ft
�e actual tank operating pressure is a function of the system pressure required. To determine the pressure in the tank when the system pressure is known, use the following calculation: Equation 7-4
Pi =
Pf + 15 – 15 A
where
Pi = Tank pressure, psi Pf = System pressure obtained from hydraulic calculations, psi
For example, if Pf = 75 psi and A = 0.5 (50 percent), the result is as follows: Pi =
75 + 15 0.5
– 15 = 165 psi
A hydraulic calculation for a sprinkler system determines the amount of water and the head or pressure the pump must deliver and maintain for proper sprinkler system operation. The pump selection is made based on flow and pressure.
PUMP CURVES Figure 7-5 illustrates a pump curve for a 1,000-gpm rated capacity pump. As mentioned, a fire pump must deliver 150 percent of the rated capacity at no less than 65 percent of the rated head (pressure). The pump curves indicate these conditions. For example, in Figure 7-5, when delivering 1,500 gpm, following
Figure 7-5 Example Pump Curve, 1,000-gpm Rated Pump Courtesy of Patterson Pump
40
Fire Protection Systems
the 8⅛-inch impeller (105-psi) curve will generate a pressure of 190 feet of water, which represents 80 percent. �is pump performs better than the code, which requires 65 percent. Each pump curve diagram also includes the following information: u Pump flow delivery capacity in gpm (horizontal line) u Pump head or pressure capability measured in feet of water and/or the corresponding pressure in head in feet (vertical line) u Brake horsepower for electric motor (straight lines slanted up to the right) u Impeller rpm (written on the top) u Range of pressure (written in the top right box) Pump selection should be made for maximum efficiency, as this will save power when the pumps are running. Before making a final decision, discuss potential pump selections with a manufacturer representative. �is can be very helpful in selecting the proper pump. Most manufacturers have selection charts that show gpm and the corresponding psi for each selection they have approved. It is good practice to use these charts to select a fire pump. In general, rpm should not be a consideration when selecting a fire pump because these pumps see very limited use, and rpm is not a factor in length of life like it is in other pumping applications. In an installation, the fire pump must be one-hour fire rated if sprinkle red and two-hour rated if unsprinklered. �e fire pump room should be kept at an ambient temperature (many installations have a low pump room temperature alarm), and it should be located on the ground floor. �e fire department must be able to reach it quickly in case of a fire. �e room must also have a floor drain. For more information on fire pumps, see NFPA 20.
41
Private Mains, Standpipes, and Hose Systems
8
Private fire service mains are the pipe and its appurtenances on private property that are between a source of water and the base of the system riser, between a source of water and the inlets to foam-making systems, between a source of water and the base elbow of private hydrants or monitor nozzles, used as fire pump suction and discharge piping, or beginning at the inlet side of the check valve on a gravity or pressure tank. Private fire service mains are used to supply fire sprinkler systems, water spray systems, foam systems, private fire hydrants, standpipe systems, monitor nozzles, hose houses, and water for other uses. Private fire service mains can be supplied by a reliable city water system or by fire pumps that take suction from a tank, pond, public system, or other reservoirs. Where connections are made to a public system, the requirements of the public health authority should be followed to prevent possible contamination of the public system. Mains that supply hydrants must be at least 6 inches in diameter. For mains that supply hydraulically calculated systems but not hydrants, the pipe size can be smaller than 6 inches if the calculations demonstrate that the main can meet the total demand at the required pressure. A fire department connection (FDC) should be provided. e FDC is used by the fire department to provide supplemental water under pressure to the systems being served. e authority having jurisdiction (AHJ) should be consulted to confirm the type and location of the FDC. Signage may be required indicating what the FDC serves (e.g., type of system, system demand, or which buildings or portions thereof). Valves are required at each source of water supply. The valves are usually post indicator valves (PIVs) (see Figure 8-1), but underground gate valves can be used where acceptable to the AHJ. In addition, every connection from a private fire service main to a building should have a listed PIV located not less than 40 feet from the building. Sectional control valves should be used to isolate secFigure 8-1 Post Indicator Valve tions of private fire service
42
Fire Protection Systems
mains. For example, sectional valves can be used to isolate a limited number of risers so a break in the underground loop would not impair an entire building. Where hydrants are provided, a valve shall be installed in the hydrant connection. e type of hydrant (number and size of outlets, type of hose thread) and the spacing of hydrants should be approved by the AHJ. Hydrants must be operable all the time; therefore, they must be inspected regularly for vandalism and other damage. ey must also be lubricated on a yearly basis. Hose houses are used by trained firefighters. e AHJ should be consulted regarding the quantity and type of hoses and other equipment that should be furnished in each hose house, as well as the number and location of hose houses. Master streams are monitor nozzles or hydrant-mounted monitor nozzles that are used to protect hazards such as combustible materials stored in yards. Any underground pipe used for a private fire service main must be listed for that purpose, and the pipe material can be ductile iron, steel, concrete, plastic, or copper. When choosing the type of material, consideration should be given to the fire resistance of the pipe, system working pressure, soil conditions, corrosion issues, and the susceptibility of the pipe to physical damage (e.g., traffic loads). During the commissioning of a private fire service main, the system should be tested and flushed. e minimum test pressure is 200 pounds per square inch (psi), or 50 psi in excess of the maximum working pressure, for a duration of two hours. Leakage from the system is permitted (see National Fire Protection Association [NFPA] 24: Standard for the Installation of Private Fire Service Mains and eir Table 8-1 Flow Rate Appurtenances for the quantity allowed). e amount of Required to Produce a actual leakage is calculated by pumping from a calibrated Velocity of 10 fps in a Main container at the specified test pressure. Pipe Size, in. Flow Rate, gpm e mains should be flushed at not less than the hydrau4 390 lically calculated flow rate (including hose allowances), at 6 880 8 1,560 a rate that provides a velocity of 10 feet per second (fps) 10 2,440 (see Table 8-1) or at the maximum flow rate available to the 12 3,520 system under fire conditions.
STANDPIPE AND HOSE SYSTEMS NFPA 14: Standard for the Installation of Standpipe and Hose Systems covers the minimum requirements for the installation of these systems. e applicable edition of the installation standard, the building code, and local amendments should be consulted for complete design and installation requirements. Standpipes provide a means of manual water application to a fire within a building. ey are connected to water supply mains or to fire pumps, tanks, and other equipment necessary to provide an adequate supply of water. According to NFPA, a standpipe system is �an arrangement of piping, valves, hose connections, and allied equipment installed in a building or structure with the hose connections located in such a manner that water can be discharged in streams or spray patterns through attached hoses and nozzles, for the purpose of extinguishing a fire and so protecting a building or structure and its contents in addition to protecting the occupants.� When designing a standpipe system, the following questions should be considered: u Where is a standpipe required�
Chapter 8: Private Service Mains, Standpipes, and Hose Systems u u u u u u
Which class of standpipe is required� What type of standpipe system is appropriate� What are the flow and pressure requirements of the system� Where should hose connections be located� What materials should be specified� What tests are required before the system is approved�
Standpipe Requirements Standpipe requirements for buildings are based on the building code and local amendments. For example, a common requirement based on the International Fire Code is for standpipes to be installed in buildings where the floor level of the highest story is located more than 30 feet above the lowest level of fire department vehicle access or where the floor level of the lowest story is located more than 30 feet below the highest level of fire department vehicle access. In addition to the applicable building code, the requirements of the AHJ should be followed regarding local amendments and firefighting methods that could affect the design of the system. Standpipe Classes Standpipe systems are grouped into three classifications. e class of system required is usually determined by the building code. u Class I: Intended for fire department use only, this type of system is equipped with a 2½-inch valve for hose attachment. u Class II: is type of system is typically equipped with a 1½-inch hose for use only by trained industrial fire brigades. (Previous editions of NFPA 14 allowed Class II systems to be used by building occupants.) u Class III: A combination of Class I and Class II, this type of system includes a 2½-inch hose connection for fire department use and a 1½-inch hose rack assembly for industrial fire brigade use. Standpipe System Types A standpipe system can be wet or dry and automatic, semiautomatic, or manual. An automatic wet standpipe is full of water and under pressure at all times. When the hose valve is opened in a wet system, water comes out through the hose and its nozzle. An automatic dry standpipe contains air or nitrogen under pressure that, when released, allows a dry pipe valve to open and water to flow into the piping system. A manual dry system does not have water in the pipes or a permanent water supply and relies on the fire department to supply the system demand through the fire department connection. A manual wet system contains water at all times but relies on the fire department to supply the system demand through the fire department connection. A semiautomatic dry system has a deluge valve that, when released, allows an automatic water supply to provide water at hose connections. A combined system supplies water to both hose connections and automatic sprinkler systems. Class I standpipes should be wet systems except where the piping is subject to freezing. In high-rise buildings, Class I standpipes shall be automatic or semiautomatic. Class II and III systems should be automatic wet systems unless they serve a facility with areas
43
44
Fire Protection Systems
subject to freezing and where the fire brigade is trained to operate the system without fire department intervention.
Flow and Pressure Requirements Pipe schedule systems are no longer allowed by NFPA 14. All systems must be hydraulically calculated. Flow Rates For Class I and III standpipes, the minimum flow rate for the most hydraulically remote standpipe is 500 gallons per minute (gpm) (250 gpm through each of two 2½-inch hose connections). Each additional standpipe requires an additional 250 gpm, up to a maximum flow rate of 1,250 gpm for buildings that are not sprinklered throughout or 1,000 gpm for buildings that are sprinklered throughout. For Class II systems, the minimum flow rate is 100 gpm. Pressure Requirements For Class I and III systems, the minimum residual pressure required at the hydraulically most remote hose connection is 100 psi. Where the static pressure exceeds 175 psi, a pressure-regulating device must be installed to limit the static and residual pressures to 175 psi. For Class II systems, the minimum residual pressure required at the hydraulically most remote hose connection is 65 psi. Where the residual pressure exceeds 100 psi, a device must be installed to limit the residual pressure at the flow required to 100 psi. Where the static pressure exceeds 175 psi, a device must be installed to limit the static and residual pressures to 100 psi. For any system, the maximum pressure allowed anywhere in the system is 350 psi, except that express mains supplying higher zones may exceed 350 psi where their material listings and the AHJ allow.
Hose Connections Hose connections should be unobstructed and located not less than 3 feet or more than 5 feet above the floor. Class I hose connections should be located: u At the main floor landing in exit stairways u On each side of the wall adjacent to the exit openings of horizontal exits (as defined by NFPA 101: Life Safety Code) u In covered mall buildings, at the entrance to each exit passageway and at the interior side of the public entrance from the exterior to the mall u At the highest landing in stairways with access to a roof where the slope is less than four in 12 Additional hose connections for Class I systems should be provided where the most remote portion of a non-sprinklered floor is more than 150 feet of travel distance from a hose connection (200 feet for a sprinklered building). In Class II systems, a hose station should be located so all portions of each floor are within 130 feet of a hose connection provided with a 1½-inch hose or within 120 feet of a hose connection provided with a hose smaller than 1½ inches. Class III systems should be provided with hose connections as required for both Class I and Class II systems. e 130-foot travel distance does not apply to Class III systems. In a fully sprinklered building, the AHJ may allow the omission of the Class II hose stations
Chapter 8: Private Service Mains, Standpipes, and Hose Systems
provided that each Class I connection is equipped with a 2½- by 1½-inch reducer with a cap and chain.
Material Selection All devices and materials that affect the performance of the standpipe system should be listed. Pipe should meet or exceed the standards listed in NFPA 14, which allows the use of the following types of pipe: u Steel u Ferrous (ductile iron) u Copper tube u Other pipe and tube types listed for this service Fittings can include: u Cast iron, malleable iron, or ductile iron (threaded, grooved, or flanged) u Steel fittings (welded, flanged, or threaded) u Other fittings listed for this service System Acceptance Tests e following tests are required for acceptance of a standpipe system: u Flushing of pipe: Underground pipe should be flushed in accordance with NFPA 24: Standard for the Installation of Private Fire Service Mains and eir Appurtenances. Piping between the fire department connection and the check valve in the inlet pipe shall be flushed with a sufficient volume of water to remove any construction debris. u Hose threads: All hose connections and fire department connections should be tested to verify their compatibility with the threads used by the local fire department. u Hydrostatic tests: All systems should be tested at a minimum of 200 psi (or 50 psi in excess of the maximum pressure where the maximum pressure exceeds 150 psi) for two hours. is includes the pipe between the fire department connection and the check valve. An air pressure leakage test at 40 psi shall be conducted for 24 hours. u Flow tests: To verify system demand, water should be flowed simultaneously from the outlets indicated in the approved hydraulic calculations of each standpipe. u Pressure-regulating devices: Each pressure-regulating device should be tested under flow and no-flow conditions to verify that the pressure setting is correct and that each device is installed in the correct location. u Main drain: e main drain valve should be opened and remain open until the system pressure stabilizes, at which time the static and residual pressures should be recorded. u Automatic dry and semiautomatic systems: ese systems should be tested by initiating flow from the most remote hose connection.
45
47
Automatic Sprinkler Systems
9
National Fire Protection Association (NFPA) 13: Standard for the Installation of Sprinkler Systems provides the minimum requirements for the design and installation of automatic fire sprinkler systems, but it also allows for alternate design approaches and system components. When designing such systems, it is important to follow all of the requirements in NFPA 13, so verify with the local authority having jurisdiction (AHJ) which edition should be used.
HISTORY OF FIRE SPRINKLERS �e first sprinkler system in the United States was installed in 1852 and consisted of perforated pipe. �e first automatic sprinkler was invented 12 years later to control, confine, and extinguish fires to prevent the loss of life and minimize the loss of property. By 1895, sprinkler system development was increasing significantly, and the Boston area alone had nine different systems. Boston experienced the most growth in this discipline because of the number of hazardous textile mills in the area. Before 1950, sprinkler heads simultaneously discharged water upward and downward. �e downward discharge quenched the fire, while the upward discharge kept the structure cool. �ese inefficient heads were subsequently replaced by upright and pendent heads. NFPA 13 NFPA 13 was first written in 1896. It was prepared in conjunction with fire service personnel, fire insurance representatives, laboratories that tested fire protection items, representatives from fire protection equipment manufacturers, contractors who installed such systems, and consulting engineers who specified and designed these systems. Since then, the standard has evolved significantly, especially in 1997 when it was expanded to include design and installation information from more than 40 other NFPA standards. �e current edition of NFPA 13 includes design criteria for underground pipe, rack storage, high-piled storage, and other unique hazards. With the unprecedented development of sprinkler system devices, installation practices, and design techniques for automatic sprinkler systems, increased diligence is required when designing and installing these systems, as the requirements have become both more complex and less uniform. As with any other code or standard, NFPA 13 gives only the minimum requirements to provide a reasonable degree of protection. Based on the owner�s preference, additional protection may be installed for a higher degree of safety. FIRE SPRINKLER SYSTEM DESIGN When designing a fire sprinkler system, the following items should be considered: u Basis of the design u Type of system to be selected u Occupancy classification
48
Fire Protection Systems u
Materials to be specified u Basic installation requirements u Hanging and restraint requirements u Design approaches u System acceptance It is essential to design a sprinkler system to fit the particular hazard of a building or structure. NFPA 13 includes requirements for general storage, high-piled and rack storage, plastic and rubber commodities storage, and other special occupancies. (Note: Requirements for storage occupancies and certain special sprinklers are not included in the scope of this chapter.)
Basis of Design �e first step in designing a fire sprinkler system is to ask the owner to complete an owner�s information certificate, which can be found in NFPA 13. �is certificate informs the designer and installer of the owner�s intended occupancy of the building, including what materials will be used and how they will be stored, preliminary construction plans of the building, and any environmental concerns, such as the possibility of microbiologically influenced corrosion (MIC). Once the designer understands the construction and intended use of the building, design documents consisting of drawings, calculations, and specifications can be prepared. �ese documents must be approved and kept readily available for further inspection and modifications if necessary. Sprinkler System Types �e factors to consider in selecting the type of sprinkler system or the type of suppression system are: u Types of building construction and contents needing protection u �e potential of a fast-growing fire developing u Valuable items in the area being protected that would be damaged by water u �e freezing potential of the area being protected Knowing this information will help determine the type of suppression system to be designed and installed. �e various types of fixed sprinkler systems are clearly defined in NFPA 13 and summarized below. Wet Pipe Systems A wet pipe system (see Figure 9-1) employs automatic sprinklers attached to a piping network containing water under pressure at all times. �e system is connected to a water supply so water discharges immediately from the sprinklers when they open. Approximately 75 percent of the sprinkler systems in use are wet pipe systems. �is type of sprinkler system is easy to maintain and is considered the most reliable. It is installed where freezing or other special requirements are not a concern. Dry Pipe Systems �e dry pipe system employs automatic sprinklers attached to a piping system containing air or nitrogen under pressure, the release of which (as from a sprinkler opening) allows the water pressure to open a valve known as a dry pipe valve (see Figure 9-2). �e water then flows into the piping system and out the opened sprinklers. A dry pipe system requires more time to get water to a fire than a wet pipe system; however, the time between
Chapter 9: Automatic Sprinkler Systems
49
Figure 9-1 Wet Pipe Sprinkler System
the sprinkler opening and the water flowing can be shortened by using quick-opening devices. �is system is used where sprinklers are subject to freezing. �e dry pipe system uses compressed air from a plant supply or a local air compressor. �e air supply will typically have a restrictive orifice to limit the rate at which compressed air is introduced into the system. �e sprinkler head orifice is much larger than the air supply pipe opening, so the opening of a sprinkler head will allow the system air pressure to drop and the dry valve to open.
Figure 9-2 Dry Pipe Valve (Left) Air pressure maintains clapper closed. (Right) Venting of air allows clapper to open and water to flow.
Preaction Systems A preaction system employs automatic sprinklers that are attached to a piping system containing air that may or may not be under pressure, with a supplemental detection system installed in the same areas Figure 9-3 Preaction Valve Riser as the sprinklers (see Figure 9-3). Actuation of the detection system and sprinklers in the case of a double-interlocked system opens a valve, which allows water to flow into the sprinkler piping system and to be discharged from any sprinklers that may be open. �is system is oen used where valuables
50
Fire Protection Systems
are stored and accidental water discharge may cause damage. Deluge Systems A deluge system employs open heads attached to a piping system and is connected to a water supply through a deluge valve, which is opened by the operation of a detection system installed in the same area as the sprinklers (see Figure 9-4). When this valve opens, water flows into the piping system and discharges from all attached heads. �is system is used in very high-hazard areas where rapid application of large volumes of water is required to quickly gain control of a fire.
Figure 9-4 Deluge Valve Riser
Combined Dry Pipe and Preaction Sprinkler Systems Combined systems employ automatic sprinklers attached to a piping system containing air under pressure, with a supplemental detection system installed in the same area as the sprinklers. Operation of the detection system actuates tripping devices, which open dry pipe valves simultaneously and without the loss of air pressure in the system. Operation of the detection system also opens approved air exhaust valves at the end of the feed main, which usually precedes the sprinklers opening. �e detection system also serves as an automatic fire alarm system. Antifreeze Systems Filing cup An antifreeze system (see Figure Water supply Water 9-5) is a wet pipe system employing automatic sprinklers attached to a 12 inches l l piping system that contains an an a W tifreeze solution and is connected Approved A Drop, g n n i indicating 5 feet to a water supply. �e antifreeze z i o e t e valve minimum r Unheated area l f u solution fills the pipes first, fol n o s o N Heated area lowed by water, which discharges immediately from sprinklers that B are opened by the heat from a fire. Check valve �e antifreeze system is no differPitch to drain (1/32-inch hole Drain valve ent than a wet system except that in clapper) the initial charge of water is mixed 1. Check valve shall be p ermitted to be omitted where sprinklers are below the level of valve A. with antifreeze, so the system may 2. The 1/32-inch hole in the check valve clapper is needed to allow for expansion of the solution during a temperature rise, thus preventing be installed in unheated areas. Addamage to sprinklers. ditional devices may be required to Figure 9-5 Antifreeze System prevent air pocket formation. Due to the possible combustibility of some antifreeze solutions, NFPA has been researching the use of antifreeze in wet pipe systems and updating standards as needed. �us, it is critical to consult the latest version of the applicable standard regarding the maximum concentration of antifreeze solution allowed.
Chapter 9: Automatic Sprinkler Systems
OCCUPANCY CLASSIFICATIONS Light Hazard Light hazard occupancies are those where the quantity and/or combustibility of contents is low and fires with relatively low rates of heat release are expected. Examples include: u Churches u Clubs u Eaves and overhangs of combustible construction with no combustibles beneath u Educational facilities u Libraries, except for large stack rooms u Museums u Nursing or convalescent homes u Offices, including data processing areas u Restaurant seating areas u �eaters and auditoriums, excluding stages and prosceniums u Unused attics Ordinary Hazard Group 1 Ordinary Hazard Group 1 occupancies are those where combustibility is low, the quantity of combustibles is moderate, stockpiles of combustibles do not exceed 8 feet, and fires with moderate rates of heat release are expected. Examples include: u Automobile parking lots and showrooms u Bakeries u Beverage manufacturing u Canneries u Dairy product manufacturing and processing u Electronic plants u Glass and glass product manufacturing u Laundries u Restaurant service areas Ordinary Hazard Group 2 Ordinary Hazard Group 2 occupancies are defined as occupancies where the quantity and/ or combustibility of contents is moderate to high, stockpiles of contents with moderate rates of heat release do not exceed 12 feet, and stockpiles of contents with high rates of heat release do not exceed 8 feet. Examples include: u Cereal mills u Chemical plants (ordinary) u Distilleries u Dry cleaners u Feed mills u Horse stables u Leather goods manufacturing u Libraries with large stack rooms u Machine shops u Metal working u Paper and pulp mills u Piers and wharves
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Fire Protection Systems u
Post offices u Repair garages u Stages u Tire manufacturing
Extra Hazard Group 1 Extra Hazard Group 1 occupancies are those where the quantity and combustibility of contents are very high and dust or other materials are present, introducing the probability of rapidly developing fires with high rates of heat release, but with little or no combustible or flammable liquids. Examples include: u Aircra hangars u Combustible hydraulic fluid use areas u Die casting u Metal extruding u Plywood and particle board manufacturing u Printing (using inks having flash points below 100°F) u Rubber reclaiming, compounding, drying, milling, and vulcanizing u Saw mills u Textile picking, opening, blending, garnetting, carding, and the combining of cotton, synthetics, wool shoddy, or burlap u Upholstering with plastic foams Extra Hazard Group 2 Extra Hazard Group 2 occupancies have moderate to substantial amounts of flammable or combustible liquids or extensive shielding of combustibles. Examples include: u Asphalt saturating u Flammable liquid spraying u Flow coating u Mobile home or modular building assemblies (where a finished enclosure is present and has combustible interiors) u Open oil quenching u Plastic processing u Solvent cleaning u Varnish and paint dipping COMPONENTS AND MATERIALS In general, all components used in a sprinkler system should be listed (i.e., approved by a third-party testing agency) and used in accordance with their listing. Certain components that do not affect system performance are not required to be listed (e.g., drain valves and signs). Sprinklers �e automatic sprinkler head is a thermosensitive device that is automatically activated when the area in which it is installed reaches a predetermined temperature. Once this temperature is met, the sprinkler head releases a stream of water and distributes it in a specific pattern and quantity over a designated area. Water reaches the sprinklers through a network of overhead pipes, and the sprinklers are placed along the pipes at regular, geometric intervals.
Chapter 9: Automatic Sprinkler Systems
Sprinkler heads shall never be stored where temperatures may exceed 100°F. Sprinkler heads shall never be painted, coated, or modified in any way aer leaving the manufacturing premises. Care should be exercised to prevent damage to sprinkler heads during handling. �e sprinkler should be selected based on the following criteria: u Temperature ratTable 9-1 Sprinkler Temperature Ratings and Temperature ings are based on Classification Color Codes the expected am- Maximum Color Code Temperature Temperature Glass Bulb Ceiling (with Fusible bient ceiling temRating Classification Color Temperature Link) perature around the Uncolored or Orange (135°F) sprinkler (see Ta100°F 135–170°F Ordinary Black or Red (155°F) ble 9-1). Where the Yellow (175°F) maximum expected 150°F 175–225°F Intermediate White or Green (200°F) temperature is less 225°F 250–300°F High Blue Blue than 100°F, ordi300°F 325–375°F Extra High Red Purple nary temperature 375°F 400–475°F Very Extra High Green Black sprinklers should be 475°F 500–575°F Ultra High Orange Black selected. Sprinklers 625°F 650°F Ultra High Orange Black located in areas ex- Source: NFPA 13 posed to heat-producing devices (space heaters, steam mains, skylights, etc.) should have higher temperature ratings to prevent accidental operation. u Orifice sizes are based on the available pressure and the required water flow rate. Larger K factors mean that less pressure is required to reach a given flow rate. u �ermal sensitivity refers to how quickly a sprinkler will respond to a change in the ambient temperature. Quick-response sprinklers increase the protection of life and property and are generally required in all new light hazard occupancies. �ey also are oen used in ordinary hazard occupancies because their faster response to a fire allows reductions in the design area, thereby resulting in smaller pipe sizes. Sprinkler Types Standard sprinkler heads are made for installation in an upright or pendent position and must be installed in the position for which they were constructed. Architects sometimes require special sprinkler types to be used for certain applications. �e many types of commercially available sprinklers include the following: u Upright: Normally installed above the supply pipe u Pendent: Installed below the pipe u Sidewall (horizontal and vertical): Similar to standard sprinkler heads except for a special deflector, which allows the discharge of water toward one side only in a pattern resembling one-quarter of a sphere. �e forward horizontal range of about 15 feet is greater than that of a standard sprinkler. For special applications, a sidewall vertical type is used. u Extended coverage: Covers more than 225 square feet per head or greater distances than standard sprinklers u Open sprinklers u Corrosion resistant: Mostly regular pendent or upright type heads used in areas where corrosive substances are present (e.g., chlorine storage rooms and salt-water reservoirs) that are coated with wax or Teflon by the manufacturer to protect against corrosives
53
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Fire Protection Systems u u u u u u u u u
u
u
u
Nozzles Dry pendent and dry upright: Used where a limited enclosure is subject to freezing; may be connected to a wet pipe system through a special dry pipe connector Quick response (QR) Quick response, extended coverage (QREC) Quick response, early suppression (QRES) Early suppression, fast response (ESFR) Ornamental Recessed: Most of the body is mounted within a recessed housing and operation is similar to a standard pendent sprinkler Flush: �e working parts of the sprinkler head extend below the ceiling into the area in which it is installed without affecting the heat sensitivity or the pattern of water distribution Concealed: �e entire body, including Table 9-2 Approved Materials for Sprinkler the operating mechanism, is above a System Pipe Material Standard cover plate, which drops when a fire Ferrous piping (welded and occurs, exposing the thermosensitive ASTM A795 seamless) assembly. �e deflector may be fixed, Welded and seamless steel pipe ASTM A53 or it may drop below the ceiling level Wrought steel pipe ASME B36.10M when water flows. Electric-resistance welded steel ASTM A135 Residential: Designed to respond to a pipe fire much faster than standard com- Copper tube (drawn, seamless) ASTM B42; ASTM B75 mercial and industrial sprinklers Seamless copper water tube ASTM B88 Wrought seamless copper and On/off sprinkler heads ASTM B251
Piping NFPA allows the use of steel pipe, copper tube, and other specially listed pipes (see Table 9-2). �e pipe selected should be based on the maximum system pressure, ambient conditions, aesthetics, and possible exposure of the pipe to fire conditions.
copper alloy tube
Fluxes for soldering applications of copper and copper alloy tube
ASTM B813
Brazing filler metal (classification BCuP-3 or BCuP-4)
AWS A5.8
Solder metal
ASTM B32
Alloy materials
ASTM B446
Plastic pipe (CPVC, PEX)
ASTM F442; ASTM F876
Source: NFPA 13 Note: Always verify approved materials with the AHJ.
Alarms �ree basic types of alarms can be part of a sprinkler system: u Vane-type water flow: �is alarm comes equipped with a small paddle that is inserted directly into the riser pipe (see Figure 9-6). �e paddle responds to water flow as low as 10 gallons per minute (gpm), which then triggers an alarm. �is type may be equipped with a delayed system (adjustable from 0 to 120 seconds) to prevent false alarms caused by normal water pressure fluctuations. u Mechanical water flow (water motor gong): �is alarm involves a check valve that lis from its seat when water flows (see Figure 9-7). �e check valve may vary as follows. �e differential type has a seat ring with a concentric groove connected by a pipe to the alarm device. When the clapper of the alarm valve rises to Figure 9-6 Vane-Type allow water to flow to the sprinklers, water enters the groove Water Flow Indicator
Chapter 9: Automatic Sprinkler Systems
and flows to the alarm-giving device. Another type has an extension arm connected to a small auxiliary pilot valve, which, in turn, is connected to the alarm system. u Pressure-activated alarm switch: �is is used in conjunction with dry pipe valves, alarm check valves, and other types of water control valves. It has contact elements arranged to open or close an electric circuit when sub jected to increased or reduced pressure. In most cases, the motion to activate a switch is given from a diaphragm exposed to pressure on one side and supported by an adjustable spring on the other side. Figure 9-7 Alarm Check Valve Riser �e alarm for a dry pipe sprinkler system is arranged with a connection from the intermediate chamber of the dry pipe valve to a pressure-operated alarm device. When the dry pipe valve trips, the intermediate chamber, typically containing air at atmospheric pressure, fills with water at the supply pressure, which operates the alarm devices. Sometimes both an outdoor water motor gong and a pressure-operated electric switch are provided. �e alarm devices for deluge and preaction systems are the same as those used for dry pipe systems. Codes require water supply control valves to indicate conditions that could prevent the unwanted or unnecessary operation of the sprinkler system. �is can be achieved by using electric switches, also called temper switches, which can be selected for open or closed contact. �e signal that indicates valve operation is given when the valve wheel is given two turns from the wide-open position. �e restoration signal sounds when the valve is restored to its fully open position. �is simply cancels the temper switch alarm.
Other Components Sprinkler system components are typically designed for a minimum pressure of 175 pounds per square inch (psi). If the pressure required in the system is higher than 175 psi, then all system components must be rated for the higher pressure. It is not unusual for systems to be designed with maximum pressures of 250 to 300 psi. BASIC INSTALLATION REQUIREMENTS Area Limitations �e maximum floor area that may be protected by sprinklers supplied on each syste m riser on any one floor is as follows: u Light hazard: 52,000 square feet u Ordinary hazard: 52,000 square feet u High-piled storage: 40,000 square feet u Extra hazard, pipe schedule: 25,000 square feet u Extra hazard, hydraulically calculated: 40,000 square feet Spacing per Sprinkler Head and Between Sprinkler Heads �e maximum spacing for standard pendent and upright sprinklers is shown in Table 9-3. Other sprinklers, such as sidewalls, extended coverage, control mode specific application
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Fire Protection Systems
Table 9-3 Spacing for Standard Pendent and Upright Sprinklers Construction Type
System Type
Protection Area, sf
Maximum Spacing, ft
Light Hazard Noncombustible
Pipe schedule
200
15
Combustible unobstructed, exposed members 3 feet or more on center
Pipe schedule
200
15
Noncombustible
Hydraulically calculated
225
15
Combustible unobstructed, exposed members 3 feet or more on center
Hydraulically calculated
225
15
Combustible obstructed, exposed members 3 feet or more on center
All
168
15
Combustible obstructed or unobstructed, exposed members less than 3 feet on center
All
130
15
All
130
15
All
Pipe schedule
90
12
All
Hydraulically calculated with density more than or equal to 0.25
100
12
All
Hydraulically calculated with density less than 0.25
130
15
Ordinary Hazard All
Extra Hazard
(CMSA), ESFR, and residential sprinklers have different rules, and NFPA 13 and the specific listings of each sprinkler should be consulted for proper design and installation methods. Delector Positions
Under unobstructed construction, the sprinkler deflector should be a minimum of 1 inch and a maximum of 12 inches below the ceiling. Under obstructed construction, the sprinkler deflector should be located in a horizontal plane between 1 inch and 6 inches below the structural members and a maximum distance of 22 inches below the ceiling/roof deck.
Obstructions to Sprinkler Discharge NFPA 13 contains numerous figures and tables to clarify where obstructions are considered too significant and could cause sprinklers to provide inadequate coverage. �ese rules apply to obstructions such as beams, soffits, privacy partitions, joists, ducts, lights, etc. In general, sprinklers should be located to minimize obstructions to discharge, or additional sprinklers should be provided to ensure adequate coverage. �e rule commonly known as the �three times rule� states that a sprinkler located within 24 inches of an obstruction should be located a distance at least three times the maximum dimension of the obstruction. For example, a sprinkler located near a 4-inch wide by 4-inch deep obstruction should be located at least 12 inches from the obstruction. In general, sprinkler deflectors should be located 18 inches above storage or other obstructions that could interrupt the discharge pattern of the sprinkler. Additional sprinklers should be installed under fixed obstructions that are more than 4 feet in width (e.g., ducts, overhead doors).
Chapter 9: Automatic Sprinkler Systems
57
System Drains All sprinkler systems must be installed so s o the system may be drained if necessary necessar y. If repairs or alterations are required, a main drain valve will allow the system sy stem to be emptied. e mptied. Wet Wet pipe systems may be installed level, while dry pipe and preaction systems must be pitched for drainage. �e required pitch is ½ inch per 10 feet Table 9-4 Drain Sizes for for Sprinkler Systems for branch lines and ¼ inch per 10 feet for mains. Riser Pipe, in. Drain Pipe, in. Mains must be pitched at least ½ inch per 10 feet 2 and smaller ¾ or larger in refrigerated areas. 2½ to 3½ 1¼ or larger �e required drain pipe pipe size as a function of the 4 and larger 2 riser size is shown in Table 9-4. Hanging and Restraint Requirements In general, all components of hanger assemblies that directly attach to the pipe or the building structure must be listed. NFPA 13 does allow a licensed Professional Engineer to certify other hangers if they meet these requir requirements: ements: u �ey can support five times the weight of the water-filled pipe plus 250 pounds at each point of piping support. u �ese points of support shall be adequate to support the system. u �e spacing between hangers does not exceed that allowed by NFPA 13. u All hanger components are ferrous. u Detailed calculations calc ulations shall be submitted showing the stresses and safety factors allowed. Sprinkler piping and hangers should not be used to support non-system components. Hanger rods shall be sized as shown in Table 9-5, and the maximum distance between hangers is shown in Table 9-6. Table 9-5 Hanger Rod Sizing Pipe Size, in.
Rod Diameter, in.
Up to and including 4
3/8
5 to 8
½
10 to 12
5/8
Table 9-6 Maximum Distance Between Between Hangers, ft Type of Pipe
Pipe Size, in. 1
1¼
1½
2
2½
3
4
6
8
Steel (except threaded lightwall)
12
12
15
15
15
15
15
15
15
Threaded lightwall
12
12
12
12
NA
NA
NA
NA
NA
Copper tube
8
10
10
12
12
12
15
15
15
CPVC
6
6½
7
8
9
10
NA
NA
NA
Except when sprinklers are less than 6 feet apart, a hanger is required on each section of pipe. Sprigs 14 feet or longer need to be restrained against lateral movement. Where sprinkler systems are subject to damage by earthquakes, bracing, restraint, and the use of flexible joints or clearances must be provided.
DESIGN APPROACHES Pipe Schedule Systems Whereas all systems were once designed on a pipe schedule basis, NFPA 13 no longer allows pipe schedules to be used except for modifications or extensions to existing systems or for new systems less than 5,000 square feet. To determine the water supply requirements for a pipe schedule, consult NFPA 13, which gives flow rates and operational durations for light and ordinary hazards.
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Fire Protection Systems
Hydraulically Calculated Systems �ree method methodss to t o determin d eterminee the required water supply using hyd hydrau raulic lic calcula calculation tionss foll follow: ow: u �e design/area method uses design/area curves (see Figur Figuree 9-8). For example, example, a light hazard system can be designed to provide a density of 0.1 gpm over a remote area of 1,500 square feet. Any point along the curve can be selected. Where quick-response sprinklers are used, the area of sprinkler operation can be reduced by up to 40 percent, depending on the elevation ele vation of the ceiling.
Figure 9-8 Design Area Curve Curve Example u
�e room design method can be used when all rooms are enclosed with walls having a fire-resistive rating equal to the required water supply duration. �is method allows the water supply requirement to be based on the sprinklers sprin klers in the room that creates the greatest demand. Where a room communicates through an unprotected opening with other rooms, up to two additional sprinklers must be included for each additional add itional room. u Special design areas: Where a building service chute (trash or linen) is protected with sprinklers,, the three most remote sprinklers shall be calculated with a minimum dissprinklers charge of 15 gpm each. In spaces where residential sprinklers can be used within the scope of NFPA NFPA 13, the design area shall include the four adjacent sprinklers that produce produce the greatest hydraulic demand.
DESIGN AND CONSTRUCTION DOCUMENTS When developing a sprinkler system design, code requir requires es certain data to be included on the working design drawings. NFPA 13 lists all of the information required, which includes the following: u Name, location, location, and address of the property in which the system will be installed u Owner and occupan occ upantt u Point of compass (north direction) u Type of construction u Distance from hydrant u Special hazard requirements, etc.
Chapter 9: Automatic Sprinkler Systems
SYSTEM ACCEPT CCEPTANCE ANCE Hydrostatic Tests When the sprinkler system�s operating pressure is 150 psi or less, the test pressure must be 200 psi, and the length of the test must be two hours. For any other operating pressure, the test must be the maximum working pressure plus 50 psi. If the test takes place during the winter, air may be temporarily substituted for water. Pneumatic Tests In addition to hydrostatic hydrostatic tests, dry dr y pipe and double-interlocked preaction systems require an air pressure leakage test. �ese systems must be tested at 40 psi for a 24-hour period and must not lose more than 1.5 psi during this period. Flushing Aer installation, underground mains, lead-in connec- Table 9-7 Underground Main Main tions, and risers must be flushed. �is operation is very Flushing Flow Rates Size, in in. Flow Ra Rate, gp gpm important, because factory-supplied pipes may contain Pipe Si 4 390 dust, rust, etc., in addition to impurities and debris col6 880 lected during installation. If not eliminated, these foreig foreign n 8 1,560 materials may block a sprinkler�s orifice and render it 10 2,440 inoperable. �e flushing rates prescribed by NFPA 13 for 12 3,520 underground mains are shown in Table 9-7. Operational Tests All water flow devices should be b e tested. NFP NF PA 13 allows up to five minutes aer flow begins before an audible alarm sounds on the premises. Dry pipe systems must have a full-flow trip test. �e test should be started by opening the inspector�s inspector�s test connection c onnection and measuring the time t ime required to trip the valve and the time for water to discharge from the inspector�s test connection. Deluge and preaction systems should be b e trip-tested through th rough both manual and automatic automatic means. All control valves should be operated under system syst em pressure to ensure proper proper operation. A main drain test should be conducted and recorded for comparison during future tests. Each pressure-reducing valve must be tested at both the maximum and normal inlet pressures.
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Basic Hydraulics for Sprinkler Systems
10
Hydraulics is a subdivision of fluid mechanics that specifically studies the behavior of liquids. When predicting the motion of a liquid, specifically water in pipes, many of the equations used can be simplified to reflect that some variables will remain constant. �is chapter describes the basic principles that govern the motion of water through pipes in fire protection systems and the assumptions that can be made in this context.
ASSUMPTIONS AND SIMPLIFICATIONS Compressibility In nearly all applications, water can be considered to be incompressible. �is means that for any given volume of water, regardless of how much external force is applied, the volume will stay the same. No matter how much pressure is applied, a gallon of water will not fit into a pint. �is seems obvious, but it is a key assumption that simplifies many of the equations that predict water flow. Density and Temperature �e density of water in a fire protection system is relatively constant. �is means that a given volume of water will always have approximately the same weight, and since the water cannot be compressed, the same amount of water by weight will always fill the same volume. �e density of many materials and fluids varies with temperature, and water is no different. �e variation, however, is small. A fire protection system installed in any space that can be occupied will be within a predictable range. In addition, the properties of water in the temperature ranges normally observed do not change significantly. Table 10-1 shows the density of water at three different temperatures as an example. As can be seen in Table 10-1, the difference in density for the temperatures Table 10-1 Density of Water at Varying likely to be observed varies less than 1 percent Temperatures from one extreme to the other. �is small Temperature, °F Density, slugs/ft3 Density, lb/ft3 variation can be ignored in calculations for 40 1.94 62.43 70 1.936 62.3 most fire protection systems. 100
1.927
62
Viscosity Viscosity is what many would describe as the �thickness� of a liquid. It�s the resistance a fluid has to being deformed. Fluids with a high viscosity, like honey, require more force to deform than fluids with a lower viscosity. Viscosity is an important property when describing flow though pipes. To visualize the effect of viscosity, consider drinking water through a straw. Water flows with little effort through the straw. Pulling a more viscous liquid like maple syrup through the same straw takes considerably more effort. �e higher viscosity of the maple syrup resists the changes in physical shape that are required for it to flow through the straw easily.
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Fire Protection Systems
�e viscosity of water is another property that can be considered constant across the conditions in which a fire protection system will be installed. �e one significant exception to this is antifreeze systems. In some cases when a fire protection system is installed in an area where the temperature may drop below 40°F, the system may be filled with an antifreeze solution rather than water. In this circumstance, the calculations to predict system performance will have to account for a slightly higher viscosity. (Check with the local authority and relative standards for the approved use of antifreeze solutions.)
One-Dimensional Flow Fire protection systems consist of a network of pipes. Flow within a pipe can be considered to be one-dimensional because it is axisymmetric and relatively uniform. �is essentially means that the flow within the pipe stays almost the same throughout the cross-section of the pipe. �e Pipe centerline variations that do occur within the flow vary with distance from the pipe wall. Flow tends to be faster in the center of the pipe and slower near the wall. Figure 10-1 shows the concept of axisymmetric flow. �ough the velocity varies from the center of the Flow velocity profile pipe to the wall, the variation is small. For most calculations the flow is assumed to be the same regardFigure 10-1 Axisymmetric Flow less of position in the pipe cross-section. Once this assumption is made, only one dimension is le: the distance along the length of the pipe. �e practical meaning of this is that there are no differences in sprinklers on the bottom of a pipe vs. the top or the pressure along the outer radius of a fitting vs. the inner radius. Only the distance through the pipe is considered. Results of Assumptions and Simplications Aer all of these assumptions, the basic formulas for flow in a pipe can be reduced to: Equation 10-1
Q = AV; V = Q/A; A = Q/V where
Q = Flow rate, gallons per minute (gpm) A = Cross-sectional area of the pipe, in2 V = Velocity of flowing water, feet per second (fps) Since the velocity of water is considered to be consistent across the cross-section of the pipe, a single number for velocity or an average velocity is all that is required. With an average velocity and an area, the volume of water over a given time or flow rate can easily be determined. Example 10-1
Consider a 4-inch Schedule 40 (inside diameter of 4.026 inches) fire main flowing 500 gpm. What is the average velocity of water flow in the pipe in feet per second� First, find the area of the pipe cross-section:
A = π x 2.012 = 12.7 in 2 = 0.0881 ft 2 �en convert gallons per minute to cubic feet per second (cfs). If 500 gpm equal 8.33 gallons per second and 1 gallon equals 0.134 cubic feet, then 8.33 gallons equal 1.11 cfs.
Chapter 10: Basic Hydraulics for Sprinkler Systems
Using Equation 10-1:
500 gpm = 0.881 ft 2 x V, or 1.11 cfs V= = 12.6 fps 0.881 ft2 PRESSURE LOSSES IN PIPES Energy Loss �e first law of thermodynamics states that energy cannot be created or destroyed. It simply changes from one form to another. �e two forms of energy of interest when describing flow though pipes are heat and pressure. James Prescott Joule, a 19th century English physicist, discovered the relationship between the friction of a moving fluid and heat. He was determined to relate a measured amount of energy in heat (or increase in temperature of a fluid) to the mechanical work done on that fluid. In his experiment, he placed a paddle inside a container of fluid and stirred the fluid with a given amount of mechanical force for a given time. He showed that stirring the fluid increased its temperature the same amount as the mechanical energy put into the paddle. To relate this experimental example to water flow in pipes, think of the paddle as the surface of the pipe. As water flows through the pipe, the portion of the water along the pipe wall is disturbed, and the water is heated a very small amount. �is heating is so small that the rise in temperature is ignored, but the first law of thermodynamics states that this energy has to come from somewhere. �e small amount of heat created is energy lost in the form of pressure. An equivalent way to express energy is a change in pressure within a given volume. For flow in a pipe, the pressure of the water along the length of the pipe decreases as the energy is lost due to the friction of the water against the pipe�s walls. Water Pressure Water pressure is the amount of force that the water exerts on its container. It is expressed in a force per unit area. �e common unit for pressure measurement in fire protection and plumbing systems in the United States is pounds per square inch (psi). Absolute Pressure vs. Gauge Pressure When measuring pressure, it is important to remember the environment in which the pressure measurement is taken. Pressure in a fire protection system, or pressure read from a typical pressure gauge, is referred to as gauge pressure, which is the difference between the pressure inside the pipe and the pressure outside the pipe. �e open atmosphere has an air pressure of between 14 and 15 psi. �e gauge is measuring how much higher the pressure inside the pipe is compared to the atmospheric pressure. �e absolute pressure inside the pipe would be the difference between the pressure in the pipe and a perfect vacuum. For example, if the atmospheric pressure is 14 psi and the gauge reads 100 psi, then the gauge pressure is 100 psi, and the absolute pressure is 114 psi. Pressure Due to Elevation In any volume of water, the pressure changes with elevation. �is is true of all fluids under the influence of gravity or any other acceleration. �e pressure varies according to the density of the fluid, not the size or shape of the container in which it�s flowing. For example, the pressure change from the top to the bottom of a 12-inch-long drinking straw stood on end will be the same as the pressure change from the top to the bottom of a 12-inch-deep
63
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Fire Protection Systems
aquarium. Even though more water is in the aquarium, the pressure change is the same since pressure is measured as force per unit area. To determine how much the pressure changes due to elevation, consider a column of water 1 square inch in area and 12 inches high. From Table 10-1, the weight of water per cubic foot is 62.3 pounds. If a square foot is 144 square inches, a column of water 1 foot high will occupy 1/144 of a cubic foot. �is means that the column of water will weigh 1/144 of 62.3 pounds, or 0.433 pound. With this information, the amount of water pressure created by elevation can be determined in any situation. In a non-flowing fire protection system, the pressure at any elevation relative to the pressure at another elevation will differ by 0.433 psi per foot of elevation. For example, if the pressure at the top of a 100-foot riser is 100 psi, the pressure at the bottom will be 143 psi. Another way to say this is that a 100-foot vertical pipe has a pressure loss of 43 psi. Example 10-2
Consider a water pump on ground level with a discharge pressure of 300 psi. Will this pump be capable of delivering water to the top of a 500-foot-tall high-rise�
500 feet x 0.433 psi/ft = 216.5 psi Yes, it will be capable. If the pump is producing 300 psi and 216.5 psi is required, then the pressure at the top will be 83.5 psi. Example 10-3
On the 10th floor of a building, a fire department standpipe requires 65 psi. If the valve on the 10th floor is 124 feet above ground level, what pressure will be required at ground level�
65 psi + 124 feet x 0.433 psi/ft = 119 psi required The Hazen-Williams Equation To make this information applicable to fire protection systems, an equation that will predict how much pressure is lost for a given pipe and given water flow rate is required. �e Hazen-Williams equation is the most commonly used way to determine pressure losses in fire protection systems. �is equation was derived empirically, which means it is based on observed results rather than theory. It predicts the pressure loss per foot of pipe as: Equation 10-2
p=
4.52 Q1.85 C1.85 d4.87
where
p = Pressure loss per linear foot of pipe, psi Q = Flow, gpm C = Roughness coefficient (Table 10-2) Table 10-2 Pipe Roughness Coefficients d = Internal diameter of the pipe, in. Pipe Material C The variable not easily understood Black steel pipe in a dry sprinkler system 100 here is C, the roughness coefficient. �is Steel pipe in a wet sprinkler system 120 variable takes into account the condition Galvanized pipe in a dry sprinkler system 120 of the pipe through which the water is Cement-lined underground pipe 140 150 flowing. If the pipe walls are very rough, Plastic (CPVC) 150 the amount of energy lost is higher than Copper pipe
Chapter 10: Basic Hydraulics for Sprinkler Systems
65
if the pipe walls are very smooth. Values for C can be as low as 70 for rough, old iron pipe or as high as 150 for perfectly smooth, new plastic pipe. Example 10-4
How much pressure is lost in a 100-foot-long, 2½-inch Schedule 40 (inside diameter of 2.47 inches) pipe flowing 250 gpm if the roughness coefficient is 120�
4.52(2501.85) p= x 100 ft = 21.5 psi 1201.85(2.474.87) Water Flow Tables �e hydraulic pipe schedule is a table of standard sprinkler system pipe sizes with associated flows that will produce the average friction loss per foot allowed in the system under consideration. (See the tables at the end of this chapter for hydraulic values in sprinkler pipe sizes up to 4 inches.) Friction Losses for Fittings and Valves �e common method for expressing friction losses for fittings and valves in fire protection is to express the loss as an equivalent length of pipe. When water flows through a fitting or valve, more energy is lost than if it were flowing through a straight section of pipe. �e additional lost energy can be accounted for by replacing the fitting or valve in the calculation by an equivalent length of straight pipe. With this simplification, losses for fittings and valves can be added into the Hazen-Williams friction loss formula. Example 10-5
How much pressure is lost in the pipe from Example 10-4 if there are four grooved 90-degree elbows in the pipe� (�e equivalent length of a grooved 90-degree elbow is 3.9 feet.)
Total length = 100 ft + (4 x 3.9 ft) = 116 ft Since other variables remain the same, the friction loss per foot remains the same:
4.52(2501.85) p= = 0.215 psi/ft x 116 ft = 24.9 psi 1201.85(2.474.87) Equivalent lengths for fittings and valves are typically provided by manufacturers, though some common fitting equivalent lengths are prescribed in codes and standards (see Table 10-3). �ese lengths are always provided with an assumed roughness coefficient (C factor) of 120. If the piping does not have a roughness coefficient of 120, the equivalent length must be adjusted according to Table 10-4. Table 10-3 Fittings and Valves
45° elbow 90° standard elbow 90° long-turn elbow Tee or cross Butterfly valve Gate valve Swing check*
Equivalent Pipe Lengths for Fittings, ft Fitting and Valve Size, in.
0.5
0.75
1
1.25
1.5
2
2.5
3
3.5
4
x 1 0.5 3 x x x
1 2 1 4 x x x
1 2 2 5 x x 5
1 3 2 6 x x 7
2 4 2 8 x x 9
2 5 3 10 6 1 11
3 6 4 12 7 1 14
3 7 5 15 10 1 16
3 8 5 17 x 1 19
4 10 6 20 12 2 22
*Due to the variation in design of swing check valves, the pipe equivalents indicated in this table are considered average.
Table 10-4 Equivalent Length Multipliers for C Factors Other than C = 120 Value of C
Multiplying Factor
100 120 140 150
0.713 1 1.33 1.51
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Fire Protection Systems
WATER EXITING THE PIPE At some point, for the purpose of a fire protection system to be realized, the water must exit the pipe. In water-based fire protection systems, this occurs through an orifice with fixed properties. �e simplest and most common way of expressing the properties of an orifice is with a number referred to as the K factor. An orifice�s K factor includes the effects of both the orifice�s size and the shape of the sprinkler or nozzle immediately before the opening that affects the amount of flow through the opening. �e expression that relates the K factor to pressure and flow is: Equation 10-3
Q = K√p where
Q = Flow, gpm K = K factor p = Pressure, psi Example 10-6
If a fire sprinkler has a K factor of 5.6 and the water pressure inside the pipe is 10 psi, how much water is flowing out of the sprinkler� Using Equation 10-3:
Q = 5.6√10 = 17.7 gpm Table 10-5A Q, gpm
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
Water Flow Table, 1-inch Schedule 40 Steel Pipe ID = 1.049 inches
Pf, psi/ft C=100
C=120
Velocity, fps
0.051 0.060 0.071 0.082 0.094 0.107 0.121 0.135 0.150 0.166 1.820 0.200 0.217 0.236 0.255 0.276 0.296 0.318 0.340 0.363 0.386 0.410 0.435
0.036 0.043 0.051 0.059 0.067 0.076 0.086 0.096 0.107 0.182 0.130 0.142 0.155 0.169 0.182 0.197 0.211 0.227 0.243 0.259 0.276 0.293 0.310
3.71 4.08 4.46 4.83 5.20 5.57 5.94 6.31 6.68 7.05 7.43 7.80 8.17 8.54 8.91 9.28 9.65 10.02 10.40 10.77 11.14 11.51 11.88
Q, gpm
33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
Pf, psi/ft C=100
C=120
Velocity, fps
0.460 0.487 0.513 0.541 0.569 0.598 0.627 0.657 0.688 0.719 0.751 0.784 0.817 0.851 0.886 0.921 9.57 0.993 1.03 1.068 1.106 1.145
0.329 0.347 0.366 0.386 0.406 0.427 0.448 0.469 0.491 0.513 0.536 0.56 0.583 0.608 0.632 0.657 0.683 0.709 0.735 0.762 0.79 0.817
12.25 12.62 12.99 13.37 13.74 14.11 14.48 14.85 15.22 15.59 15.96 16.34 16.71 17.08 17.45 17.82 18.19 18.56 18.93 19.31 19.68 20.05
Chapter 10: Basic Hydraulics for Sprinkler Systems
Table 10-5B Q, gpm
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52
67
Water Flow Table, 1¼-inch Schedule 40 Steel Pipe ID = 1.049 inches
Pf, psi/ft C=100
C=120
Velocity, fps
0.013 0.016 0.019 0.022 0.025 0.028 0.032 0.036 0.039 0.044 0.048 0.052 0.057 0.062 0.067 0.072 0.078 0.084 0.089 0.095 0.102 0.108 0.114 0.121 0.128 1.135 0.142 0.150 0.157 0.165 0.173 0.181 0.189 0.198 0.206 0.022 0.224 0.233 0.242 0.252 0.261 0.271 0.281
0.009 0.011 0.013 0.015 0.018 0.020 0.023 0.025 0.028 0.031 0.034 0.037 0.041 0.044 0.048 0.052 0.056 0.060 0.064 0.068 0.072 0.077 0.082 0.086 0.091 0.096 0.102 0.107 0.112 0.118 0.123 0.129 0.135 0.141 0.147 0.153 0.160 0.166 0.173 0.180 0.186 0.193 0.200
2.14 2.36 2.57 2.79 3.00 3.21 3.43 3.64 3.86 4.07 4.29 4.50 4.71 4.93 5.14 5.36 5.57 5.79 6.00 6.21 6.43 6.64 6.86 7.07 7.29 7.50 7.71 7.93 8.14 8.36 8.57 8.79 9.00 9.21 9.43 9.64 9.86 10.07 10.29 10.50 10.71 10.93 11.14
Q, gpm
53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94
Pf, psi/ft C=100
C=120
Velocity, fps
0.291 0.301 0.312 0.322 0.333 0.344 0.355 0.366 0.377 0.389 0.401 0.412 0.424 0.437 0.449 0.461 0.474 0.487 0.500 0.513 0.526 0.540 0.553 0.567 0.581 0.595 0.609 0.623 0.638 0.652 0.667 0.682 0.697 0.712 0.728 0.743 0.759 0.775 0.791 0.807 0.823 0.840
0.208 0.215 0.222 0.230 0.238 0.245 0.253 0.261 2.690 0.278 0.286 0.294 0.303 0.312 0.320 0.329 0.338 0.347 0.357 0.366 0.375 0.385 0.395 0.405 0.414 0.424 0.435 0.445 0.455 0.466 0.476 0.487 0.498 0.508 0.519 0.531 0.542 0.553 0.565 0.576 0.588 0.599
11.36 11.57 12.00 12.21 12.43 12.64 12.86 13.07 13.07 13.29 13.50 13.71 13.93 14.14 14.36 14.57 14.79 15.00 15.21 15.43 15.64 15.86 16.07 16.29 16.50 16.71 16.93 17.14 17.36 17.57 17.79 18.00 18.21 18.43 18.64 18.86 19.07 19.29 19.50 19.71 19.93 20.14
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Fire Protection Systems
Table 10-5C Q, gpm
10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68
Water Flow Table, 1½-inch Schedule 40 Steel Pipe ID = 1.61 inches
Pf, psi/ft C=100
C=120
Velocity, fps
0.006 0.009 0.012 0.015 0.019 0.023 0.027 0.032 0.037 0.042 0.048 0.054 0.060 0.067 0.074 0.082 0.089 0.097 0.106 0.114 0.123 0.133 0.142 0.152 0.162 0.173 0.184 0.195 0.206 0.218
0.004 0.006 0.008 0.011 0.013 0.016 0.019 0.023 0.026 0.030 0.034 0.039 0.043 0.048 0.053 0.058 0.064 0.069 0.075 0.082 0.088 0.095 0.101 0.109 0.116 0.123 0.131 0.139 0.147 0.155
1.57 1.89 2.20 2.52 2.83 3.15 3.46 3.78 4.09 4.41 4.75 5.04 5.35 5.67 6.98 6.30 6.61 6.93 7.24 7.56 7.87 8.19 8.50 8.82 9.13 9.45 9.76 10.08 10.39 10.71
Q, gpm
70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100 102 104 106 108 110 112 114 116 118 120 122 124 126 128
Pf, psi/ft C=100
C=120
Velocity, fps
0.23 0.242 0.255 0.359 0.281 0.294 0.308 0.322 0.336 0.351 0.366 0.381 0.396 0.412 0.428 0.445 0.461 0.478 0.495 0.513 0.530 0.548 0.566 0.585 0.604 0.623 0.642 0.662 0.682 0.702
0.164 0.173 0.182 0.191 0.200 0.210 0.220 0.230 0.240 0.250 0.261 0.272 0.283 0.294 0.306 0.317 0.329 0.341 0.353 0.366 0.378 0.391 0.404 0.418 0.431 0.445 0.458 0.472 0.487 0.501
11.02 11.34 11.65 11.97 12.28 12.59 12.91 13.22 13.54 13.85 14.17 14.48 14.80 15.11 15.43 15.74 16.06 16.37 16.69 17.00 17.32 17.63 17.95 18.26 18.58 18.89 19.21 19.52 19.84 20.15
Chapter 10: Basic Hydraulics for Sprinkler Systems
69
Table 10-5D Water Flow Table, 2-inch Schedule 40 Steel Pipe ID = 2.067 inches Q, gpm
30 35 40 45 50 55 60 63 66 69 72 75 78 81 84 87 90 93 96 99 102 105 108 111 114 117 120 123 126
Pf, psi/ft C=100
C=120
Velocity, fps
0.014 0.019 0.024 0.030 0.037 0.044 0.051 0.056 0.061 0.066 0.072 0.077 0.083 0.089 0.095 0.102 0.108 0.115 0.122 0.129 0.137 0.144 0.152 0.160 0.168 0.176 0.184 0.193 0.202
0.010 0.010 0.017 0.021 0.026 0.031 0.037 0.040 0.044 0.047 0.051 0.055 0.059 0.064 0.068 0.073 0.077 0.082 0.087 0.092 0.097 0.103 0.108 0.144 0.120 0.126 0.132 0.138 0.144
2.87 3.35 3.82 4.30 4.78 5.26 5.74 6.02 6.31 6.60 6.88 7.17 7.46 7.75 8.03 8.32 8.61 8.89 9.18 9.47 9.78 10.04 10.33 10.61 10.90 11.19 11.47 11.76 12.05
Q, gpm
129 132 135 138 141 144 147 150 152 154 156 158 160 162 164 166 168 170 172 174 176 178 180 185 190 195 200 205 210
Pf, psi/ft C=100
C=120
Velocity, fps
0.211 0.220 0.229 0.239 0.249 0.258 0.269 0.279 0.288 0.295 0.304 0.311 0.318 0.325 0.333 0.340 0.349 0.355 0.364 0.371 0.378 0.386 0.395 0.416 0.437 0.458 0.480 0.502 0.526
0.150 0.157 0.164 0.170 0.177 0.184 0.192 0.199 0.206 0.211 0.217 0.222 0.227 0.232 0.238 0.243 0.249 0.254 0.260 0.265 0.270 0.276 0.282 0.297 0.312 0.327 0.343 0.359 0.376
12.33 12.62 12.91 13.20 13.48 13.77 14.06 14.34 14.60 14.80 15.00 15.20 15.30 15.50 15.70 15.90 16.10 16.30 16.50 16.70 16.90 17.00 17.20 17.70 18.20 18.70 19.10 19.60 20.10
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Fire Protection Systems
Table 10-5E Q, gpm
40 45 50 55 60 65 70 75 80 85 90 95 100 103 106 109 112 115 118 121 124 127 130 133 136 139 142 145 148 151 154 157 160 163 166 169 172 175 178 179
Water Flow Table, 2½-inch Schedule 40 Steel Pipe ID = 2.469 inches
Pf, psi/ft C=100
C=120
Velocity, fps
0.010 0.013 0.015 0.018 0.022 0.025 0.029 0.033 0.037 0.041 0.046 0.050 0.055 0.059 0.062 0.065 0.068 0.072 0.075 0.079 0.082 0.086 0.090 0.094 0.098 0.102 0.106 0.110 0.114 0.119 0.123 0.128 0.132 0.137 0.142 0.146 0.151 0.156 0.161 0.164
0.007 0.009 0.011 0.013 0.015 0.018 0.020 0.023 0.026 0.029 0.033 0.036 0.040 0.042 0.044 0.046 0.049 0.051 0.054 0.056 0.059 0.066 0.064 0.067 0.070 0.073 0.076 0.079 0.082 0.085 0.088 0.091 0.094 0.098 0.101 0.104 0.108 0.111 0.115 0.117
2.68 3.02 3.35 3.69 4.02 4.36 4.69 5.03 5.36 5.70 6.03 6.37 6.70 6.90 7.10 7.30 7.51 7.71 7.91 8.11 8.31 8.51 8.71 8.91 9.11 9.32 9.52 9.72 9.92 10.12 10.32 10.52 10.72 10.92 11.12 11.33 11.53 11.73 11.93 12.00
Q , gpm
180 182 184 186 188 190 192 194 196 198 200 202 204 206 208 210 212 214 216 218 220 222 224 226 228 230 235 240 245 250 255 260 265 270 275 280 285 290 295 300
Pf, psi/ft C=100
C=120
Velocity, fps
0.166 0.169 0.172 0.176 0.179 0.183 0.187 0.190 0.194 0.197 0.201 0.205 0.209 0.213 0.216 0.200 0.224 0.228 0.232 0.236 0.240 0.244 0.248 0.252 0.257 0.261 0.271 0.282 0.293 0.304 0.316 0.327 0.339 0.351 0.363 0.375 0.388 0.401 0.414 0.427
0.118 0.120 0.123 0.125 0.128 0.131 0.133 0.136 0.138 0.141 0.144 0.146 0.149 0.152 0.154 0.157 0.160 0.163 0.166 0.168 0.171 0.174 0.177 0.180 0.183 0.186 0.194 0.201 0.209 0.217 0.225 0.234 0.242 0.250 0.259 0.268 0.227 0.286 0.296 0.305
12.10 12.20 12.30 12.40 12.60 12.70 12.90 13.00 13.20 13.30 13.40 13.50 13.60 13.70 13.80 13.90 14.10 14.20 14.40 14.60 14.70 14.90 15.10 15.30 15.60 15.80 16.00 16.10 16.40 16.90 17.10 17.40 17.70 18.10 18.50 18.80 19.00 19.40 19.80 20.10
Chapter 10: Basic Hydraulics for Sprinkler Systems
Table 10-5F Q, gpm
30 40 50 60 70 80 90 100 110 120 130 140 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240 245 250 255 260 265 270 275
71
Water Flow Table, 3-inch Schedule 40 Steel Pipe ID = 3.068 inches
Pf, psi/ft C=100
C=120
Velocity, fps
0.002 0.004 0.005 0.007 0.010 0.013 0.016 0.019 0.023 0.027 0.031 0.036 0.041 0.043 0.046 0.049 0.051 0.054 0.057 0.060 0.063 0.066 0.069 0.073 0.076 0.079 0.083 0.086 0.090 0.093 0.097 0.101 0.011 0.109 0.113 0.117 0.121 0.125
0.001 0.003 0.004 0.005 0.007 0.009 0.011 0.014 0.016 0.019 0.022 0.026 0.029 0.031 0.033 0.035 0.037 0.039 0.041 0.043 0.045 0.047 0.049 0.052 0.054 0.057 0.059 0.062 0.064 0.067 0.069 0.072 0.075 0.078 0.080 0.083 0.086 0.089
1.30 1.74 2.17 2.60 3.04 3.47 3.91 4.34 4.77 5.21 5.64 6.08 6.51 6.73 6.94 7.16 7.38 7.60 7.81 8.03 8.25 8.46 8.68 8.90 9.11 9.33 9.55 9.77 9.98 10.20 10.42 10.63 10.85 11.07 11.28 11.50 11.72 11.94
Q, gpm
280 285 290 295 300 305 310 315 320 325 330 335 340 345 350 355 360 365 370 375 380 385 390 395 400 405 410 415 420 425 430 435 440 445 450 455 460 465
Pf, psi/ft C=100
C=120
Velocity, fps
0.129 0.134 0.138 0.142 0.147 0.151 0.156 0.161 0.165 0.170 0.175 0.180 0.185 0.190 0.195 0.200 0.206 0.211 0.216 0.222 0.227 0.233 0.239 0.244 0.250 0.256 0.262 0.268 0.274 0.280 0.286 0.292 0.298 0.305 0.311 0.317 0.324 0.330
0.092 0.095 0.098 0.102 0.105 0.108 0.111 0.115 0.118 0.122 0.125 0.129 0.132 0.136 0.139 0.143 0.147 0.151 0.154 0.158 0.162 0.166 0.170 0.174 0.178 0.183 0.187 0.191 0.195 0.200 0.204 0.208 0.213 0.217 0.222 0.226 0.231 0.236
12.15 12.37 12.59 12.80 13.02 13.24 13.45 13.67 13.89 14.11 14.32 14.54 14.76 14.97 15.19 15.41 15.62 15.84 16.06 16.28 16.49 16.71 16.93 17.14 17.36 17.58 17.79 18.01 18.23 18.45 18.66 18.88 19.10 19.31 19.53 19.75 19.96 20.18
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Fire Protection Systems
Table 10-5G Q, gpm
100 125 150 175 200 225 250 275 300 325 350 375 400 425 450 475 500 510 520 530 540 550 560
Water Flow Table, 4-inch Schedule 40 Steel Pipe ID = 4.026 inches
Pf, psi/ft C=100
C=120
Velocity, fps
0.005 0.008 0.011 0.014 0.018 0.023 0.028 0.033 0.039 0.045 0.052 0.059 0.067 0.074 0.083 0.091 0.101 0.104 0.108 0.112 0.116 0.120 0.124
0.004 0.006 0.008 0.010 0.013 0.016 0.020 0.024 0.028 0.032 0.037 0.042 0.048 0.053 0.059 0.065 0.072 0.074 0.077 0.080 0.083 0.086 0.089
2.52 3.15 3.78 4.41 5.04 5.67 6.30 6.93 7.56 8.19 8.82 9.45 10.08 10.71 11.34 11.97 12.60 12.85 13.11 13.36 13.61 13.86 14.11
Q, gpm
570 580 590 600 610 620 630 640 650 660 670 680 690 700 710 720 730 740 750 760 770 780 790
Pf, psi/ft C=100
C=120
Velocity, fps
0.128 0.132 0.137 0.141 0.145 0.150 0.154 0.159 0.163 0.168 0.173 0.178 0.183 0.187 0.192 0.197 0.203 0.208 0.213 0.218 0.224 0.229 0.234
0.091 0.094 0.097 0.101 0.104 0.107 0.110 0.113 0.117 0.120 0.123 0.127 0.130 0.134 0.137 0.141 0.145 0.148 0.152 0.156 0.160 0.163 0.167
14.37 14.62 14.87 15.12 15.37 15.63 15.88 16.13 16.38 16.63 16.89 17.14 17.39 17.64 17.89 18.15 18.40 18.65 18.90 19.16 19.41 19.60 19.91
73
Hydraulic Calculations
11
National Fire Protection Association (NFPA) 13: Standard for the Installation of Sprinkler water-based fire Systems defines the method of calculating the predicted performance of water-based protection systems. Most building codes reference this document as their source for hydraulic calculation procedures. DENSITY/AREA METHOD
In commercial and residential occupancies, sprinkler systems are typically required to be capable of providing a specific density of water flow over a given area. For example, a sprinkler system protecting office space is most commonly required to provide 0.1 gallon per minute (gpm) per square foot over 1,500 square feet. �is means that the water flowing out of each sprinkler must average 0.1 gpm for every square foot of floor space that particular sprinkler is protecting. NFPA 13 provides requirements regarding the density and area required for a given occupancy or hazard, but ultimately it is the responsibility of the engineer of record and the authority having jurisdiction (AHJ) to make the final determination of what density and area will be required. Consider the plan view of a sprinkler system as shown in Figure 11-1. �e rectangular area is protected by sprinklers spaced at 14 feet by 14 feet. Assume that this space must be protected with a density of 0.1 gpm per square foot over 1,500 square feet. To prove that
Figure 11-1 Plan View View of Sprinkler System
74
Fire Protection Systems
the system syste m is able to provide the required water flow rate over any 1,500 square feet within wit hin the protected area, the hydraulically most remote 1,500 square feet must be found. NFPA 13 prescribes the method of determining the hydraulically hydraulically most remote area. To find the number numbe r of sprinklers flowing, divide divi de 1,500 by the th e area of coverage per sprinkler (196 square feet). �is results in 7.65 sprinklers. NFPA 13 does not permit a �partial� sprinkler; therefore, the number of sprinklers must be rounded up to eight. �e shape of the remote area is also prescribed by NFPA 13. It must be at least 1.2 times the square root of the area in length along the direction of the branch lines, as shown below: 1.2√1,500 = 46.5 ft
�e hydraulically most remote area is shown in Figure 11-2.
Figure 11-2 Hydraulically Most Remote Remote Area
Beginning the Calculation
Now that the flowin Now flowingg sprinklers have been determined, the calculation can begin. Assume that all of the sprinklers in this example have a K factor of 5.6. Each sprinkler is protecting protecting 196 square feet at a density of 0.1 gpm per pe r square foot. �is means that each sprinkler must flow 19.6 gpm. To determine what pressure is required for a K = 5.6 sprinkler to flow 19.6 gpm, use Equation 10-3 (Q = K√p): 19.6 gpm = 5.6√p p = (Q/K)2 = (19.6/5.6)2 = 12.25 pounds per square inch (psi)
�us, each sprinkler in the remote area must be fed with a pressure of 12.25 psi or higher. �e calculation begins at the single most remote sprinkler and works back toward the water source. Figure 11-3 assigns hydraulic node points to all of the relevant locations in the system. Sprinkler S1 is the farthest from the water source, so the calculatio calc ulationn begins at S1. Since the minimum min imum pressure pressure at any sprinkler must be 12.25 psi, the calculation will increase from 12.25 psi. To determ determine ine the pressure at sprinkler S2, the fricti f riction on loss created by water
Chapter 11: Hydraulic Calculations
75
Figure 11-3 Hydraulic Node Points
flowing from S2 to S1 must be found. Friction loss is predicted using the Hazen-Williams equation (Equation 10-2). In this case, the flow in the pipe between S1 and S2 is 19.6 gpm. For this example, assume the system is wet and has a C factor of 120. �e inside diameter of the pipe can be found in Table 11-1. (Assume all piping in this example is Schedule 40). Table 11-1 Inside Diameters for Schedule 10 and Schedule 40 Steel Pipe, in. Pipe
1 in.
1¼ in.
1½ in.
2 in.
2½ in.
3 in.
4 in.
6 in.
S10 S40
1.097 1.049
1.442 1.380
1.682 1.610
2.157 2.067
2.635 2.469
3.260 3.068
4.260 4.026
6.357 6.065
From Equation 10-2: p=
4.52 Q1.85 4.52(19.61.85) = = 0.125 psi/ft C1.85 d4.87 1201.85(1.0494.87)
Since there are 14 feet of pipe and no fittings between S1 and S2, the pressure loss between these two nodes is 1.76 psi. Given that the pressure at node S1 is 12.25 psi, the pressure at S2 must be 12.25 + 1.76, or 14 psi. At node S2 is a sprinkler also with a K factor of 5.6. Since the pressure at node S2 is now known, the flow out of this sprinkler can be determined as follows: Q = K√p = 5.6√14 = 21 gpm
With sprinkler S1 flowing 19.6 gpm and sprinkler S2 flowing 21 gpm, the amount of water flowing in the pipe feeding these two sprinklers (S3 to S2) must be 40.6 gpm. Using the same procedure, the pressure at node S3 can be found. �e pressure loss per foot between S3 and S2 will be: 4.52 Q1.85 4.52(40.61.85) p = 1.85 4.87 = = 0.482 psi/ft C d 1201.85(1.0494.87)
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Fire Protection Systems
Adding the pressure from S2 (14 psi) to the pressure loss from the pipe to the next node, the pressure at node S3 is found to be 20.7 psi. �e procedure is again repeated for the next sprinkler and section of pipe, this time with more flow and a larger diameter (for the 1¼-inch pipe between S4 and S3). Q = K√p = 5.6√20.7 = 25.5 gpm 25.5 gpm + 40.6 gpm = 66.1 gpm 4.52 Q1.85 4.52(66.11.85) p= = = 0.312 psi/ft C1.85 d4.87 1201.85(1.384.87)
Adding the pressure from S3 (20.7 psi) to the pressure loss from the pipe to node S4, the pressure at node S4 is found to be 25.1 psi. �e procedure is repeated for the next sprinkler and section of pipe, again with more flow and a larger diameter (for the 1½-inch pipe between S4 and M1). Q = K√p = 5.6√25.1 = 28.1 gpm 28.1 gpm + 66.1 gpm = 94.2 gpm 4.52 Q1.85 4.52(94.21.85) p = 1.85 4.87 = = 0.284 psi/ft C d 1201.85(1.614.87)
�e piping between S4 and M1 contains the first fitting in this example (fittings where the sprinkler itself is attached are not counted). When the loss for a reducing tee or elbow is calculated, its equivalent length must be included as the smaller pipe size. Node M1 is a tee with sizes of 3 inches and 1½ inches, so the equivalent length must be included as 1½-inch pipe. Common equivalent lengths are listed in Table 11-2. Table 11-2 Equivalent Lengths of Common Fittings (for Schedule 40 Pipe), ft Fitting
45° elbow 90° elbow Tee or cross Butterfly valve Gate valve Check valve
1 in.
1¼ in.
1½ in.
2 in.
2½ in.
3 in.
4 in.
6 in.
1 2 5 — — 5
1 3 6 — — 7
2 4 8 — — 9
2 5 10 6 1 11
3 6 12 7 1 14
3 7 15 10 1 16
4 10 20 12 2 22
7 14 30 10 3 32
Using this information, the pressure at node M1 can be found. �e distance from node S4 to M1 is 7 feet, and the equivalent length of the 3-inch by 1½-inch tee is 8 feet of 1½inch pipe. �e distance between the two in the calculation is therefore 15 feet. �e pressure at M1 is then: 15 ft x 0.284 psi/ft = 4.26 psi 4.25 psi + 25.1 psi = 29.4 psi
�e calculation up to this point is illustrated in Figure 11-4. From here, the loss between nodes M1 and M2 can be calculated. Since the flow from M1 to S4 is 94.2 gpm and there is no sprinkler at node M1, the flow from M1 to M2 must also be 94.2 gpm. �e loss between nodes M1 and M2 can be calculated as: 4.52 Q1.85 4.52(94.21.85) p = 1.85 4.87 = = 0.0123 psi/ft C d 1201.85(3.0684.87)
Chapter 11: Hydraulic Calculations
Figure 11-4 Illustration of Density/Area Method Calculation
�e required pressure at node M2 can then be calculated as 29.6 psi. At node M2, the flow splits into two directions. Some water goes to node M1, and some goes to node S8. It has already been determined how much is flowing to M1, so the flow to S8 must be found. Equivalent K Factors
All of the branch lines in this example are exactly the same. Most importantly, both branch lines included in the remote area are exactly the same. Since they are identical, an equivalent K factor can be used to find the amount of water flowing into another branch line at a different pressure. Remember from Chapter 10 that a K factor is not only a function of orifice size, but also of shape or configuration. �is can include an entire branch line. Using the information known at this point, a K factor for the typical branch line in this example can be found. �e pressure at the feed end of the branch line is 29.4 psi, and the flow is 94.2 gpm. Using Equation 10-3: Q = K√p = 94.2 gpm = K√29.4 psi Q/√p = K = 94.2 gpm/√29.4 psi = 17.4
With a K factor of 17.4 for the entire branch line, the flow of the branch line at a different pressure (the pressure at node M2) can be easily found. Again, use Equation 10-3: Q = K√p = 17.4√29.6 = 94.7 gpm
�is yields an expected result; at a slightly higher pressure, the branch flows slightly more water. �e total flow for the calculation is now known. �e flow from M2 to M1 is 94.2 gpm, and the flow from M2 to S8 is 94.7 gpm—adding to a total flow from the riser (node RSR) of 189 gpm. Result
For the final required pressure at the riser, the loss between nodes M2 and RSR must be found. Between nodes M2 and RSR are 99 feet of pipe. In addition, there is a 3-inch 90-degree elbow for a total of 106 feet. Using Equation 10-2: p=
4.52 Q1.85 4.52(1891.85) = = 0.0446 psi/ft C1.85 d4.87 1201.85(3.0684.87)
Multiplying this value by the length of 106 feet yields a loss of 4.73 psi. Adding to the required pressure at node M2 gives 34.3 psi as a final pressure.�is means the system as shown will require a flow and pressure of 189 gpm at 34.3 psi at node RSR to satisfy the area and density prescribed. ELEVATION CHANGES
�e example calculated above does not include any elevation changes. In practice, all systems have elevation changes (i.e., systems are not installed on the floor). Assume that
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all of the piping in the example is at an elevation of 10 feet above the floor. What would the required pressure be in the riser at floor level if the riser is a 3-inch pipe� To find the answer, add an additional 10 feet for the vertical pipe and 7 feet for a 90-degree elbow at the top of the riser: (10 ft + 7 ft)(0.0446 psi/ft) + 34.3 psi = 35.1 psi
Add the loss due to the increase in elevation: 10 ft x 0.433 psi/ft = 4.33 psi
Adding the elevation loss to the required pressure at the top of the riser results in a pressure of 39.4 psi. Most systems will include elevation changes at various points in the network of piping as well. �ese changes must be accounted for as the calculation progresses so the correct pressure is used for each flowing sprinkler. HYDRAULIC CALCULATION FORMS
NFPA 13 details how calculation work must be shown. Regardless of how the calculation is performed (either by hand or by soware), this format is still used to show the numbers throughout the calculation. As an example, Table 11-3 shows the start of the example calculation from earlier in this chapter. Table 11-3 Step 1 of the Example Calculation Calcu lation in NFPA 13 Format Node 1
Elevation
Node 2
Elevation
S1
10 f t
S2
K Factor
5. 6
10 f t
Flow Added in This Step
Nominal Pipe Diameter
Total Flow
Actual Pipe Diameter
19.6 gpm
1 in.
19.6 gpm
Fittings: Pipe, ft Quantity and Fittings, Equiv. ft Length Total, ft
1.049 in.
C Factor Pressure Loss per Foot
Total Notes Elevation Friction
14
120
12.25 0
14
0.125 psi/ft
1.76
Each block like the one in Table 11-3 represents a single pipe. When the calculation is finished, each pipe or equivalent K factor should have a block showing what was calculated. Table 11-4 shows the first two pipes in the example calculation. Table 11-4 Steps 1 and 2 of the Example Calculation in NFPA NFPA 13 Format Node 1
Elevation
Node 2
Elevation
S1
10 ft
S2
10 f t
S2
10 f t
S3
10 f t
K Factor
5.6
5.6
Flow Added in This Step
Nominal Pipe Diameter
Total Flow
Actual Pipe Diameter
19.6 gpm
1 in .
19.6 gpm
1.049 in.
21 gpm
1 in .
40.6 gpm
1.049 in.
Fittings: Quantity and Equiv. Length
Pipe, ft
C Factor
Fittings, ft Total, ft
Pressure Loss per Foot
14
120
14 14 14
0.125 psi/ft 120 0.482 psi/ft
Total Notes Elevation Friction
12.25 0 1.76 14 0 6.75
Chapter 11: Hy Hydraulic draulic Calculations
79
Two numbers carry over from one pipe to the next. In the flow column, the total flow is cumulative. For each sprinkler, the flow of that individual sprinkler is added in the upper box, and the total flow up to that t hat point (including (including that sprinkler) is in the lower box. If the node is simply a pipe size change where there is no flow, the upper box would be zero. In the pressure column, the total pressure loss as the calculation progresses is in the top box labeledd �Total. labele �Total.�� �at top box is the sum of the three boxes from f rom the pipe above it; meaning meani ng that the top box is the cumulative pressure, and the bottom two boxes are the pressure losses from friction and elevation (or gain from f rom elevation if the elevation change is negative) in that pipe. Table Table 11-5 shows the first two steps ste ps and the final step ste p of the example calculation. calc ulation. Table 11-5 Steps 1 and 2 and XX of the Example Calculation in NFPA NFPA 13 Format Node 1
Elevation
Node 2
Elevation
S1
10 ft
S2
10 ft
S2
10 f t
S3
10 f t
K Factor
5.6
5.6
Flow Added in This Step
Nominal Pipe Diameter
Total Flow
Actual Pipe Diameter
19.6 gpm
1 in .
19.6 gpm
1.049 in.
21.0 gpm
1 in .
40.6 gpm
1.049 in.
94.2 gpm
3 in .
Fittings: Quantity and Equiv. Length
Pipe, ft
C Factor
Fittings, ft Total, ft
Pressure Loss per Foot
14
120
12.25
0.125 psi/ft
0
14 14
Total Notes Elevation Friction
14
0.482 psi/ft
1.76 14.0 0 6.75
2 elbows
109
120
29.6
7 ft each
14
120
... M2 RSR
10 ft
17.4
0 ft
189 gpm
3.068 in.
123
0.0446 psi/ft
4.33 5.49
Final pressure and flow: 39.4 psi, 189 gpm
AREA MODIFICATIONS
�e design density dens ity and area prescribed by either eithe r the engineer enginee r of record or NFPA NFPA 13 may or may not be the final area calculated. In a number of situations the area is either increased or decreased. Some examples of area modifications are listed in Table 11-6. Table 11-6 Common Area Modifications Modifications Quick-response sprinklers
Dry systems or doubleinterlock preaction systems Sloped ceilings
For wet pipe systems using quick-response sprinklers, the design area can be reduced by as much as 40%. The amount of reduction is based on the ceiling height. See NFPA NFPA 13 for the area reduction formula and restrictions on its use. For dry systems and double-interlock preaction systems, the design area must be increased by 30%. Since these systems are filled with air, the air must be exhausted before the water will flow. The increase in area is required due to the increased amount of time it will take for water to arrive at the sprinkler. For most systems, the design area must be increased by 30% if the system is installed under a ceiling that is sloped more than 2 in 12.
Example 11-1
Using the example system in the earlier part of the chapter, how would the remote area change if the system were dry rather than wet�
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For dry systems, the design area must be increased by 30 percent, which results in a design area of 1,950 square feet. To find the number of sprinklers along a branch line: 1.2√1,950 = 53 ft
�is length still results in four sprinklers per branch line. �e difference is that now the remote area must include 10 sprinklers to add up to 1,950 square feet. Figure 11-5 shows the new remote area.
Figure 11-5 Example 11-1 Plan View
�e two additional sprinklers are added closer to the main, not at the end of the branch line. �is is important to note since it is a common mistake to include the two sprinklers at the end of the third branch line rather than the two at the root of the branch line. �e reason the two sprinklers closest to the main must be included is due to differences in water flow. �e two sprinklers closest to the main will flow more water and, therefore, increase the friction loss in the main as it flows from the riser. LOOPED AND GRIDDED PIPING
In many cases, the water may flow along more than one path. Looped and gridded systems sy stems can be challenging to calculate by hand. In most cases, these systems are designed using soware that can easily solve much more complex systems of equations. Even so, it is helpful to understand what the soware is doing and be able to make estimates without it. As a simple example, consider a standpipe system with two standpipes. For a standpipe system, 500 gpm at 100 psi is required at the top of the most remote standpipe, with 250 gpm flowing from other standpipes. �e system is shown in Figure 11-6. In this example, the flow and loss in each of the single paths can be easily determined. �e problem is the looped piping. No simple formula can be used to determine how much water is flowing through each pipe in the loop. To work through this problem, start with all of the known quantities and find the losses in the single paths (the vertical pipes). Since the 250-gpm standpipe standpipe is closer and less de-
Chapter 11: Hy Hydraulic draulic Calculations
81
Figure 11-6 Standpipe System System with Looped Piping
Figure 11-7 Water Flow Flow Paths in Loops
manding, the 500-gpm 500 -gpm standpipe will start the calculation. calc ulation. �ere is 75 feet of 4-inch piping with an internal diameter of 4.026 inches, a tee at the base with an equivalent length of 20 feet, and a starting pressure of 100 psi at the top. Assume the piping is all Schedule 40 and the C factor is 120. �e required pressure pressure at the base of the riser is then: 4.52(Q 1.85) 100 psi + (75 ft)(0.433 psi/ft) + (75 + 20)( ) = 139 psi 1201.85(4.0264.87)
�e next step is to determine how much water is flowing through each leg of the loop so pressure losses can be calculated. Figure 11-7 designates the three paths in the loop at the base of the risers. Based on the figures, the following flow relationships are known: QB + QC = 500 gpm, or QC = 500 – QB QA – QB = 250 gpm, or QA = QB + 250 QA + QC = 750
It should be noted at this point that not all of these flows will always be positive. �is example is simple enough that the direction of flow can be easily seen. In many cases, however, it may not be clear which direction the water is flowing in all sections of piping. �e important thing to remember is that simply because a flow is negative, it does not necessarily mean that an equation or the answer is wrong. It just means that water may be flowing in the opposite direction from what was expected. From here, the expressions for friction losses through each path must be incorporated. To simplify the process, the variables that will remain the same for each section can be consolidated. Since each pipe in the loop lo op has the same C factor and diameter diamete r, this portion of the Hazen-Williams equation can be calculated, and a new constant (T) can be substituted: sub stituted: T=
4.52 = 9.91 x 10-8 120 (6.0654.87) 1.85
A useful detail det ail in calculating looped piping is the fact that the press pressure ure at any given node point must be the same regardless of from which direction it comes. In this example, it is known that the pressure pressure at the base of the 500-gpm riser is 139 13 9 psi; therefore, the calculation of pressure losses in each leg of the loop must start at 139 psi. Since the loop also comes back to a common node point at the beginning and the pressure at this beginning node must be the same coming from both sides of the loop, the pressure losses through each leg of the loop must be equal. �e effect this fact has on this calculation is that the sum of the pressure losses in paths A and B must equal the pressure loss in path C. When these
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pressure losses match, the pressure of the water arriving at the base of the riser will be the same regardless of from which leg it comes. To match up the pressure losses, the flow through each path will vary. To express this as an equation, add the lengths of each path and the equivalent lengths of the fittings in that path to the Hazen-Williams equation, substituting T for the constant values. Path A is 25 feet long, path B is 150 feet long with two 90-degree elbows at 14 feet each for a total of 178 feet, and path C is 125 feet long with a 90-degree elbow at 14 feet and a tee at 30 feet for a total of 169 feet. �e resulting equation is then: 25TQA1.85 + 178TQB1.85 = 169TQC1.85
Substituting the flow relations from earlier: 25T(QB + 250)1.85 + 178TQB1.85 = 169T(500 – Q B)1.85
�e equation is now down to a single variable and can be solved. A non-linear equation of this type, however, cannot easily be solved algebraically. With access to soware, a calculator, or a spreadsheet, a solution can be found quickly, but without those tools, trial and error substituting guesses and adjusting is most likely the fastest method. In this example, a little reasoning can yield a good first guess. Looking at the loop, no fittings and very little pipe are between the water source and the first standpipe, or path C. Also, the equivalent lengths aer fittings are included for each of the other two paths are similar. With this information, it seems likely that the amount of flow through paths B and C will also be similar. Aer several iterations, the flow that satisfies the equations above is found to be Q B = 216 gpm. With a known quantity for Q B, Q C can be found; therefore, the pressure loss along path QC can be found: QC = 500 – Q B = 500 – 216 = 284
�en substitute the flow in path C in the reduced Hazen-Williams equation to find the friction loss: 169TQC1.85 = 0.579 psi
Since the pressure losses around both sides of the loop are the same, this pressure loss is added to the 139 psi required at the base of the standpipe. �e required pressure at the start of the loop is then 139.579 psi, or rounded to 140 psi. To complete the calculation, the loss from the final 50 feet of pipe between the start of the loop and the water supply is added: 140 psi + (50 x
4.52(7501.85) ) = 141 psi 1201.85(6.0654.87)
�e final required flow and pressure at the water source are 750 gpm and 141 psi.
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Fireghting Foam
12
Firefighting foam is a substance made of water, foam concentrate, and air that is used to suppress fires by coating the fuel source, thus preventing the fire�s contact with oxygen. �e mixture forms a stable blanket that has a lower density than oil, gasoline, and water. Foam is the primary extinguishing agent used for flammable liquid (Class B) fires. High-expansion foams are also acceptable for Class A fires. �e following National Fire Protection Association (NFPA) standards shall be consulted for specific design requirements as applicable: u NFPA 11: Standard for Low-, Medium-, and High-Expansion Foam u NFPA 16: Standard for the Installation of Foam-Water Sprinkler and Foam-Water Spray Systems u NFPA 30: Flammable and Combustible Liquids Code u NFPA 403: Standard for Aircra Rescue and Fire-Fighting Services at Airports u NFPA 409: Standard on Aircra Hangars u NFPA 1150: Standard on Foam Chemicals for Fires in Class A Fuels
HOW FOAMS EXTINGUISH FIRE Firefighting foam works to extinguish fires in the following ways: u Smothering the fuel source u Separating the fire from the fuel source u Cooling the fuel and surrounding surfaces u Suppressing the release of flammable vapors Criteria for Foam to Be Effective For foam to be fully effective in suppressing a fire, the following criteria must be met: u �e liquid (fuel) must be below its boiling point at the ambient conditions of temperature and pressure. u Care must be taken in the application of the foam to liquids with a bulk temperature higher than 212°F. At this temperature and above, foam forms an emulsion of steam, air, and fuel, which may produce a four-fold increase in volume when applied to a tank fire, with dangerous frothing or overflow of the burning liquid. u �e liquid must not be unduly destructive to the foam used, or the foam must not be highly soluble in the liquid (fuel). u �e liquid must not be water-reactive. u �e fire must be a horizontal surface fire. �ree-dimensional (falling fuel) or pressurized fires cannot be extinguished by foam unless the hazard has a relatively high flashpoint and can be cooled to extinguishment by the water in the foam.
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FOAM CHARACTERISTICS Drainage Rate �e discharge rate measures how long it takes for the discharged foam to drain from the expanded foam mass, with the rate based on how long it takes 25 percent of the solution to drain from the foam. Fast, or short, drain times reflect a more fluid foam. Slow, or long, drain times indicate a less fluid foam, but these foams cover the surface more slowly, which means more contact time with the fuel source. Expansion Rate �e expansion rate is the volume of finished foam divided by the volume of foam solution. Foams are divided into three expansion rates—low, medium, and high—based on their ability to fill a space: u �e expansion rate of low-expansion foams is less than 20 times. �ese foams are low viscosity, mobile, and able to quickly cover large areas. u �e expansion rate of medium-expansion foams is between 20 and 200. �ey are used to fill large volumes, flood surfaces, and fill cavities. u �e expansion rate of high-expansion foams is more than 200. �ey are suitable for enclosed spaces such as hangars, where quick filling is needed, but they also can be used to fill large volumes, flood surfaces, and fill cavities. TYPES OF FOAMS Foams are selected for specific applications according to their properties and performance (see Table 12-1). Some foams are thick, viscous, and form tough heat-resistant blankets over burning liquid surfaces; other foams are thinner and spread more rapidly. Aqueous Film-Forming Foam Aqueous film-forming foam (AFFF) is the most widely used type of firefighting foam based on its fast fire control and knockdown. It is appropriate for use on hydrocarbon fuels and is widely used in aircra hangars and military installations. AFFF is water-based and frequently contains a hydrocarbon-based surfactant, which allows it to spread over the surface of hydrocarbon-based liquids. When discharged, it forms an aqueous film on the surface of the flammable liquid, providing superior extinguishing capabilities compared to protein or fluoroprotein foams. AFFF is also ver y fluid, so it can quickly flow around obstacles. Table 12-1 Foam Characteristics
Foam Type
1
Efficiency2
1
Foam Expansion3
Hydrocarbons
Polar Liquids
Low
Medium
High
AFFF
3
0
Y
Y
N
AR-AFFF
3
3
Y
Y
N
P
1
0
Y
N
N
FP
2
0
Y
Y
N
FFFP
3
0
Y
Y
N
AR-FP
2
3
Y
Y
N
AR-FFFP
3
3
Y
Y
N
AFFF: Aqueous film-forming foam, AR: Alcohol-resistant, P: Protein, FP: Fluoroprotein, FFFP: Film-forming fluoroprotein 0: No efficiency, 1: Low efficiency, 2: Good efficienc y, 3: Excellent efficiency 3 Low: Expansion ratio between 2 to 1 and 20 to 1, Medium: Expansion r atio between 20 to 1 and 20 0 to 1, High: Expansion ratio more than 200 to 1. Source: Chemguard 2
Chapter 12: Fireghting Foam
Alcohol-Resistant Aqueous Film-Forming Foam Polar solvent/alcohol liquids have the ability to destroy a firefighting foam blanket, so alcohol-resistant AFFF was developed. When discharged, a protective film separates the foam from the fuel and prevents the destruction of the foam blanket; thus, AR-AFFF is very effective on hydrocarbon and water-miscible fires. Protein Foam Protein is a very stable foam made of naturally occurring sources of protein such as hoof, horn, and feather meal. It is intended for use on hydrocarbon fuels only. Because of its stability, it is slow moving compared to synthetic foams, but it has good heat resistance and burnback. Protein foam has slow knockdown characteristics, but it provides post-fire security at an economical cost. Fluoroprotein Foam Fluoroprotein (FP) foam offers the same benefits as regular protein foams, but due to the addition of fluorochemical surfactants, it offers faster mobility, has improved resistance to fuel contamination/pickup, and is compatible with dry chemicals. FP foam is intended for use on hydrocarbon fuels and some oxygenated fuel additives. FP foam can be applied directly on the fuel�s surface. Alcohol-Resistant Fluoroprotein Foam Alcohol-resistant FP foam offers the same benefits as FP foam, but it is also effective on water-soluble fuels such as methyl alcohol, ethyl alcohol, and acetone by forming a protective membrane between the foam and the fuel source. Film-Forming Fluoroprotein Film-forming fluoroprotein (FFFP) is a protein-based foam concentrate with the addition of a fluorochemical surfactant, which releases an aqueous film on the surface of a hydrocarbon fuel for improved mobility and faster extinguishment. FFFP combines the fuel tolerance and burnback resistance of an FP foam with increased knockdown. Alcohol-Resistant Film-Forming Fluoroprotein Alcohol-resistant FFFP offers the same benefits as FFFP and also is resistant to water-soluble fuels. Class A Foam Concentrate Class A foam concentrate is used in addition to water to help extinguish Class A fires. When mixed with water, it allows the water to blanket the fuel source rather than running off it; thus, less water is necessary with the use of Class A concentrates. According to the National Institute of Standards and Technology, water treated with Class A foam concentrate can wet a Class A fuel up to 20 times more rapidly and is three to five times more efficient at fire extinguishment than untreated water. Class A foam concentrates can also be used as a fire barrier to increase the moisture content in Class A combustibles to prevent them from igniting. PROPORTIONING Foam concentrate is mixed with water in a process called proportioning. �e correct ratio of foam concentrate to water is essential for optimum performance.
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Percentages Different foams are proportioned at different percentages (ratios), which are listed on the foam container. For example, 3 percent concentrates are mixed with water at a ratio of 97 parts water to 3 parts foam. Lower proportioning percentage foams are preferred when possible because more foam concentrate can be transported and stored than higher proportioning percentage foams. Proportioning Methods Proportioning can be accomplished in the following ways. Pre-Mix/Dump-In �is is the simplest method, requiring nothing more than mixing pre-measured portions of water and foam concentrate. It is not practical for fixed (piped) industrial applications. Balanced-Pressure Proportioning Systems �is method comprises a pressure-rated vessel with an internal, reinforced elastomeric bladder containing the foam concentrate. �e system�s water pressure squeezes the bladder, forcing the foam concentrate into a proportioner with a metering device. �e foam is stored in an atmospheric foam storage tank with an electric positive-displacement pump, and an automatic pressure-balancing valve regulates the foam to match the water pressure. Line Proportioner In this method, pressurized water flows through a line proportioner (eductor), creating a negative pressure area where suction draws the foam concentrate from an atmospheric foam storage tank. Around the Pump A fire pump is used in this method. A portion of the fire pump discharge is diverted through a line proportioner, which is piped to the suction side of the pump to form a loop around the pump. �e line proportioner produces a foam solution with the incoming water in the loop piping in a ratio such that when proportioned with fire pump intake water, the desired percentage of foam solution is produced. Water-Driven Foam Proportioner �e water-driven foam proportioner assembly is installed in the main water line (riser). �e system�s water flow rate determines the amount of foam concentrate that is injected into the water supply, delivering the correct percentage of foam solution to the discharge devices regardless of varying flow rates and pressures.
Water Pressure Proportioner pressures should not exceed 200 pounds per square inch (psi), as foam quality deteriorates at higher pressures. DISCHARGE DEVICES Once the foam concentration is correctly mixed (proportioned) with water, air must be added to produce the expanded foam. �is is accomplished using an aspirated or non-aspirated discharge device. With an aspirated device, the foam solution passes through an orifice, past air inlets, into a mixing area, and through a discharge device. With a non-aspirated device, the foam solution passes through an orifice and a stream deflector to produce droplets of solution that combine with air between the device outlet and the fuel surface.
Chapter 12: Fireghting Foam
NFPA and UL classify discharge devices by the way they apply foam to the liquid�s surface as follows: u NFPA classifications: Type 1 delivers the foam gently onto the liquid�s surface without the foam being submerged or the surface being agitated. Type 2 does not deliver foam gently onto the surface, but it is designed to lessen submergence of the foam and agitation of the surface. u UL classifications: Type 1 delivers foam without submergence. Type 2 delivers foam with partial submergence. Type 3 delivers in a manner that causes the foam to fall directly onto the surface and in a manner that causes general agitation. Many types of discharge devices are used with foam. �ey include but are not limited to the following: u Nozzles u Monitors u Sprinkler heads u Foam chambers u Foam makers u Foam generators
GUIDELINES FOR FIRE PROTECTION WITH FOAMS �e following general rules apply to the application and use of ordinary foams: u Applying the foam more gently requires a lower total amount of foam and produces more rapid extinguishment. u Successful use of foam depends on the rate at which it is applied. Application rates are described as volume of foam per fuel surface area per minute (i.e., gallons per minute per square foot). Increasing the application rate reduces the time required to extinguish the fire. Increasing the rate more than three times the minimum rate does not provide much more improvement in extinguishment time. u In general, foams will be more stable when they are generated with clean water at an ambient temperature between 35°F and 80°F. Water containing known impurities may adversely affect the foam�s quality. u Foams are also adversely affected by air containing combustion products. It is best to locate foam makers to the side of the hazard being protected, rather than directly overhead. u Recommended pressure ranges should be observed for all foam-making devices. �e foam�s quality will deteriorate if these limits (either high or low) are exceeded. STORAGE A foam storage tank and its contents must be inspected and tested at least yearly or as required by NFPA 25: Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems. Storage conditions (temperature variations, sunlight, and type of concentrate) affect the shelf life of foam concentrates. Storing different types and brands of foam in the same container is typically not acceptable. For specific recommendations, contact the foam manufacturer. ENVIRONMENTAL IMPACT OF FOAM Contemporary UL-Listed or military specification-approved foam concentrates are specifically formulated to provide maximum firefighting capabilities with minimal environmental impacts and human exposure hazards. All concentrates are biodegradable in both the natural environment and sewage treatment facilities. However, foam solutions generally
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have a high biological oxygen demand (BOD)—that is, they extract high levels of oxygen to break down. �is is an issue in the natural environment and where the foam is discharged to wastewater treatment plants. By federal and state laws, all attempts should be made to prevent discharge to waterways, even under emergency conditions. Prior to discharge to water treatment plants, the facility operator should be contacted to discuss the volume, rate, and expected time to discharge to their system.
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Water Mist Systems
13
Water mist systems were developed to provide a fixed fire protection system using water as the key extinguishing media, similar to an automatic sprinkler system or water spray (deluge) system. �e key difference of water mist systems is the droplet size and the impact the droplet size has relating to the efficiency of the water in controlling and/or extinguishing a fire. Water mist systems are defined by NFPA 750: Standard on Water Mist Fire Protection Systems as �a water spray for which the Dv0.99, for the flow-weighted cumulative volumetric distribution of water droplets, is less than 1,000 microns at the minimum design operating pressure of the water mist nozzle.� Dv0.99 refers to the amount of water discharged from the nozzles—i.e., 99 percent of the water volume must have droplets smaller than 1,000 microns in size. (In comparison, a typical sprinkler water droplet is 1,500+ microns in size.) �e minimum pressure of the water mist nozzle is the basis for the measurement of droplet size. As a comparison, most current water mist systems require minimum pressures as high as 1,000 pounds per square inch (psi), depending on the technology selected, whereby a typical sprinkler may operate at as low as 7 psi.
HISTORY OF WATER MIST �e motivation to develop technology to create smaller droplets and use less water was associated with two key fire protection issues. First, due to previous fires and loss of life on merchant ships at sea, regulations known as SOLAS (safety of life at sea) were adopted. All ships with more than 20 passengers were required to install fire sprinklers. �e technical challenges to installing a regular sprinkler system (i.e., water supplies, balancing the ship during water discharge, bulkhead penetrations, and pipe sizes) were addressed by the development and use of water mist systems. Due to their smaller pipe sizes, smaller water supplies, etc., ships could accommodate water mist systems more easily than sprinkler systems. �e second market development was the technical challenges associated with the installation of automatic sprinkler, deluge water spray, or clean agent systems in many land-based applications. For example, water supplies were sometimes limited, water runoff was an environmental issue, and new pipe installation was severely restricted in existing structures. For these reasons, water mist systems were found to be an alternative to more conventional fire protection systems. PERFORMANCE PRINCIPLES OF WATER MIST Water mist controls and extinguishes a fire by impacting two sides of the fire triangle: heat and oxygen. Water mist affects these two properties through three primary methods: heat extraction, oxygen displacement, and radiant heat blocking.
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Fire Protection Systems
�e first way that water mist controls and extinguishes a fire is through heat extraction. Water mist does not cool fires in the same method as typical wet pipe sprinkler systems, which are able to wet and cool the fuel itself due to the size and velocity of the comparatively large water droplets created by an ordinary sprinkler�s deflector. Water mist systems, with a substantially smaller droplet size, quickly extract heat from the hot gases and flames. �is is due to the surface area of the particle—the rate of heat absorption is a function of the surface area of the water droplet, not the volume of the water droplets. As the water mist droplets are much smaller than other water-based systems, the surface area per gallon of water is dramatically increased. When a water mist system discharges, the droplets are rapidly heated and converted into steam, which in turn consumes the energy of the fire. When sufficient energy is removed from the fire, the temperature of the flame drops below the minimum level required to maintain combustion, and the fire extinguishes. �e steam also plays a role in oxygen displacement. Water droplets expand during evaporation (up to 1,600 times), causing the water vapor to displace the air surrounding the droplet. �e application of water mist into a hot compartment causes rapid steam creation, displacing the combustion-fueling air within the space. �is process is particularly effective with an extremely large or hot fire, as such conditions cause rapid vaporization of the water. Lastly, the steam blocks radiant heat. A combination of the large amounts of steam generated during the extinguishment process and the water droplets themselves creates an effective thermal barrier, attenuating the heat transfer between the flames and the fuel while also reducing the radiation of the flames to unburned surfaces, thus slowing the spread of the fire.
Conditions For a water mist system to control and extinguish a fire, the following key conditions must be present: u Open flames (deluge applications) u Light hazard (or limited ordinary hazards) for closed-head systems u Limited volumes of the risk being protected u Limited heights u Limitations on ventilation u Limited fuel types and quantities of combustibles Based on these conditions, a water mist system will perform well as a deluge application in a limited-volume, enclosed space if the fuel type is limited, if an open flame is anticipated in a fire scenario, and if the ventilation is controlled to some degree. In a sprinkler alternative application, water mist will perform well within a light hazard occupancy (with limited ordinary hazard spaces). STANDARDS AND APPROVALS �e key standards for water mist systems utilized in North America are: u FM Approval Standard for Water Mist Systems (Class Number 5560) u NFPA 750 u UL 2167: Standard for Water Mist Nozzles for Fire Protection Service �e earliest approvals were associated with the International Maritime Organization (IMO), with sprinkler alternatives for passenger ships and local application systems (used to protect engine equipment in lieu of carbon dioxide) being the predominant approvals.
Chapter 13: Water Mist Systems
FM Global approves both deluge and sprinkler alternative systems (light and ordinary hazard). �e Class 5560 test protocols are the basis for all land-based system approvals, and each approval is based on a volume limitation (deluge) or square footage and ceiling height (sprinkler alternative). �ese approvals are typically system approvals, not component approvals such as those seen with conventional sprinkler systems. Water mist systems are sold inclusive of nozzles, pressure units, strainers, valving, and some level of technical support. Some of FM Global�s approvals for specialty water mist systems are: u Protection of Machinery in Enclosures with Volumes Not Exceeding 9,175 3 u Protection of Combustion Turbines in Enclosures with Volumes Not Exceeding 9,175 3 u Protection of Non-Storage Occupancies, Hazard Category 1 u Protection of Wet Benches and Other Similar Processing Equipment u Protection of Industrial Oil Cookers u Protection of Computer Room Raised Floors It is important to note that generalized listings should not be broadly relied on without verifying that the performance stated by the listing meets the needs of the particular protection scenario. �e listings have two shortcomings: a simplified test protocol and specific performance objectives. �e simplified test protocols may not capture the details of all possible real-world conditions. For example, the FM approval for the Protection of Combustion Turbines in Enclosures with Volumes Not Exceeding 9,175 3 only contains a mock-up of a combustion turbine enclosure; the mist is tested against exposed and shielded spray fires with sheet metal used for shielding, but the mock-up does not include the turbine body and associated components and tubing. Careful consideration must be employed to accurately determine what components were tested for the listing and how that applies to the desired protection scenario. In addition, with many of the approving organizations, water mist is tested against extremely specific settings using precise criteria. For example, IMO tests for accommodations and public spaces only require the fire be controlled (not extinguished) for 10 minutes, in the philosophy that firefighting crews will arrive on the scene to manually extinguish the fire within that timeframe. However, the machinery room tests require full extinguishment. It is important to accurately assess the desired protection scheme and compare it to the specific listing to determine if the approval tests meet the real-world application.
WATER MIST SYSTEM TYPES �e two types of water mist systems are single and twin fluid. Single Fluid �e single-fluid system employs either a pump unit or cylinder supplies of gas to increase the water pressure to the design requirements. �e water supply for the system may be a potable water supply, if available, or a stored water tank or cylinder. �e quantity of water depends on the anticipated system demand and the discharge duration. FM allows for a limited discharge duration of 10 minutes for certain deluge applications, while NFPA 750 requires enough gas and water for two 30-minute discharges. �ese types of systems may use a stored cylinder arrangement for both water and gas. �e network of pipes from the pressure device (pump or cylinders) to the nozzles is required to be capable of withstanding the pressures anticipated in the system and must not contribute scale, rust, etc., that may clog the nozzles. Since water mist nozzle orifices are extremely small compared to sprinklers, all water mist systems require an integral
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Fire Protection Systems
strainer on the incoming nozzle orifice and in the water supply to prevent deposits from clogging the nozzles. Single-fluid systems are offered with open (deluge) nozzles and closed, fusible bulb (sprinkler alternative) options. Each manufacturer has different listings, designs, and spacing requirements for their nozzles and system components. Droplet sizes for single-fluid system range from 50 to 200 microns; however, this measurement depends on the location of the water droplet sample and the sophistication of the measuring equipment. Nozzles are further divided into impingement and pressure jet models. Impingement nozzles rely on a solid jet of water impacting a deflector and subsequently atomizing into small drops. �e velocity of the water and the shape of the impingement surface determine the angle of discharge, the drop size, and the spray momentum. Impingement-type nozzles are generally employed with low- and medium-pressure systems and create relatively large water droplets. Pressure jet nozzles rely on specialized system components to drive water through a tiny orifice at very high velocities, causing a breakup of the water stream into mist as it exits the nozzles. Pressure jet nozzles typically require higher operating pressures than impingement nozzles, but they can create a much finer and more uniform water mist. NFPA 750 further defines single-fluid systems based on the system pressure: u Low pressure: 175 psi or less u Intermediate pressure: 175 to 500 psi u High pressure: More than 500 psi As the system pressure has a direct correlation to system component requirements, pipe types, installation complexity, pumps, tanks, and life-cycle costs, these technical issues associated with pressure should be considered in the pre-design stage.
Twin Fluid In lieu of developing all of the required nozzle pressure at the starting point (via a pump or cylinders) and transmitting the water under pressure through the pipe network, NFPA 750 provides for the option of a twin-fluid system. �is type of water mist system utilizes a propellant gas (steam, air, or nitrogen) and water, with the two media routed through separate pipe networks to the discharge device. (Note: FM considers a twin-fluid water mist system using nitrogen as the propellant to be a hybrid system.) At the discharge device (nozzle, emitter, or atomizer), the two fluids are combined to produce the water mist. �e advantages of a twin-fluid system are efficiency and small water droplets. �e separate propellant network of pipes to the discharge device allows for a lower pressure within the system, yet enables the technology to create smaller water droplets and less water consumption than a single-fluid system. Many twin-fluid systems operate at less than 120 psi, with some operating with pressures as low as 25 psi. Testing with twin-fluid discharge devices has demonstrated that a substantial number of water droplets is below the 10-micron size, creating more droplets per gallon of water and thus more surface area to absorb heat, causing a higher rate of steam conversion per gallon of water discharged. Twin-fluid nozzles create mist by using the gas and nozzle geometry to shear the water as it exits the system, creating a uniform mist discharge. Twin-fluid nozzles can control the angle of the discharge pattern, discharge rate, and drop size distribution. SYSTEM DESIGN �e design of a water mist system should start with a review of the hazard and the performance characteristics of the system. If the risk being protected exceeds the volume and/or
Chapter 13: Water Mist Systems
height restrictions of the approval agencies, if the fuel load is different or of a larger quantity compared to the testing, or if oxygen levels below 16 percent will not be acceptable (deluge applications), then water mist may not be the appropriate system choice. �e reliability of a water mist system must also be considered. Water mist systems typically incorporate equipment and concepts that are generally avoided in customary sprinkler systems. Higher water pressures increase the chances of piping or fitting failures, while a small discharge orifice size increases the chances of nozzle plugging. �e control systems generally require local detection to trigger an electrically released solenoid, adding logic controls and increasing the chances of individual equipment (and therefore system) failure. Another key design consideration is the customer�s budget. As all water mist systems require higher pressures and more sophisticated components to develop and deliver smaller droplet sizes, these systems are likely more expensive than other fire protection technologies such as automatic sprinklers, water spray, and clean agents. �us, prior to the selection and design of any water mist system, it is recommended that the hazard, system design parameters, and motivation for using water mist be confirmed with both the building owner and the water mist manufacturer. �e design information required for any water mist technology includes the following: u Risk to be protected (area and volume) u Type of risk (e.g., turbine enclosure, machinery space, light hazard sprinkler alternative) u Type of fuel anticipated (class A, class B flammable liquids, etc.) u Maximum ceiling height for any space protected u Ventilation into risk (options to shut down ventilation) u Water supply flow and pressure (existing, extension from domestic supply, self-contained, etc.) u Duration of water mist discharge u Insurance underwriter or approving agency u Other motivations for use (water use, environmental safety, contamination, etc.) u Why other system types were eliminated from consideration u Commercial limitations With this information, a design approach may be selected. As different water mist systems have unique design limitations, the designer may elect to review the design parameters directly with the manufacturers to determine the best system option for the design requirements. �e system designer is recommended to solicit the above technical information as required to establish the scope of supply for the contractor to develop a quote. As the water mist system may be a small portion of the overall fire protection scope of supply (and price), it is recommended that the water mist project�s value be clearly established at the time of bidding to ensure that the designer may utilize the option to compare system alternatives. �e designer also will need to consider the requirements for a system of electrical detection to activate the water mist system if a deluge or local application is specified. Electrical detectors, manual pull stations, alarms, and control panels may be required. If a pump unit is used to pressurize the water mist system, consideration should be given to the need for a standby power supply and/or electrical transfer switch if an electric water mist pump is employed. Auxiliary devices for the system, such as flow-measuring devices, onsite testing, etc., are identified in NFPA 750 and NFPA 20: Standard for the Installation of Stationary Pumps.
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Fire Protection Systems
In the design of a twin-fluid system, additional consideration should be given to the dual network of piping required for each discharge device. �is requirement may restrict the use of a twin-fluid system in an occupancy with limited space allocated for fire protection. Further, nitrogen storage and refill capabilities need to be considered.
COMPARISONS TO OTHER FIRE PROTECTION TECHNOLOGIES �e use of water mist is a viable option assuming the technical and commercial issues have been vetted. Following is an overview of the technical advantages and issues to review when considering water mist in lieu of other fire protection technologies. Water Mist vs. Sprinklers u Reduced water demand (less than 20 percent for nonresidential systems) u Improved cooling and radiation attenuation u Reduced footprint of equipment and pipe network u Reduced water discharge from head damage or inadvertent operation u Effective against class A and class B fuels u Decreased water damage to the building and surrounding environment Water Mist vs. Water Spray u Oxygen displacement (local and global) u Combustion chemistry interference u Fuel cooling u Radiation attenuation u Reduced firefighting runoff containment and disposal costs Water Mist vs. Clean Agents u Improved maintenance, reliability, and life-cycle u Fully approved for occupied spaces (nontoxic) u No discharge delay; attacks fire in the earliest stages u Less restrictive enclosure integrity u Extended/unlimited agent supply u No/low agent costs to all parties u No potential for decommissioning of the system Technical Issues to Consider u High pressure required compared to sprinklers and water spray u Pipe network must be corrosion resistant and able to withstand higher pressures u Limits on system volumes (deluge) u Limits on nozzle elevations (deluge and sprinkler alternative) u Limited installer experience (notably high-pressure systems) u Component complexity and availability u Life-cycle costs
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Carbon Dioxide Systems
14
Carbon dioxide (CO2) is naturally present in the atmosphere in very small amounts (0.03 percent) and is a normal product of human and animal metabolism. However, an increase in its concentration in the air (to more than 6 or 7 percent) is dangerous for humans. At room temperature, carbon dioxide is a gas that is colorless, odorless, inert, electrically nonconductive, and noncorrosive. CO2 is liquefied by compression and cooling and converted to a solid state by cooling and expansion. An unusual property of carbon dioxide is that it cannot exist as a liquid at pressures below 60 pounds per square inch gauge (psig) (75 psi absolute). �is pressure is known as the triple-point pressure at which carbon dioxide may be present as a solid, liquid, or vapor. Below this pressure, it must be either a solid or a gas, depending on the temperature. If the pressure in a CO 2 storage container is reduced by bleeding off vapor, some of the liquid will vaporize, and the remaining liquid will get colder. At 60 psig, the remaining liquid will be converted to dry ice at a temperature of -69°F (-56°C). Further reduction in the pressure will convert all of the material to dry ice, which has a temperature of -110°F (-79°C). �e same process takes place when liquid carbon dioxide is discharged into the atmosphere—a large portion of the liquid flashes to vapor with a considerable increase in volume. �e rest is converted into finely divided particles of dry ice at -110°F. �is dry ice, or �snow,� gives the discharge its typically cloudy, white appearance. �e low temperature also causes water to condense from the air, so ordinary water fog tends to persist for a while aer the dry ice has evaporated. When carbon dioxide is discharged into an enclosed area, a cloud or fog develops, which is due to the condensation that results from the dry ice forming. �e dry ice disappears shortly, which is why extinguishing by cooling is minimal. When CO2 is discharged into an enclosed area at 34 percent concentration by volume, the temperature in the area drops nearly 80°F very quickly, but it immediately begins to rise. In two minutes, the temperature rises 35°F, and in six minutes it rises 50°F. �e temperature then will slowly continue to rise to that of surrounding area.
CARBON DIOXIDE AS A FIRE SUPPRESSION AGENT As a fire suppression agent, carbon dioxide is beneficial because it leaves no residue to clean up aer discharge and does not contribute harmful chemicals to the drainage system. It is approximately 50 percent heavier than air and moves slowly downward, so discharge nozzles must be located at the upper portion of the protected area. Its extinguishing effect occurs because the oxygen content in the surrounding air is reduced below the 15 percent threshold needed for combustion to take place.
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Fire Protection Systems
When CO2 is discharged on electrical equipment, it does not produce an electrical shock. It also does not spread the fire to surrounding areas, which may happen when a fire hose with a solid stream is used. However, if a stream of CO 2 directly hits an operating piece of hot equipment, thermal shock and damage could result. Carbon dioxide may be used in the following applications: u Flammable liquids and gases u Electrical hazards (computer rooms, transformers, generators, and switch-gear rooms) u Ovens, broilers, ranges, and kitchen stove exhaust ducts u Combustibles with unique value (e.g., legal documents, films, books) CO2 should not be used in the following areas: u When oxidizing materials (chemicals containing their own oxygen supply) are present u Where personnel cannot be quickly evacuated u When reactive metals are present (e.g., sodium, potassium, magnesium, titanium) Carbon dioxide is stored in either high- or low-pressure containers. High-pressure containers store CO2 at 850 psi and 70°F, and each cylinder may weigh 5, 10, 15, 20, 25, 35, 50, 75, 100, or 125 pounds. �e CO2 content per cylinder is 60 to 68 percent, and the balance within the cylinder is an inert propellant gas. Figure 14-1 shows the typical arrangement of high-pressure containers. Low-pressure containers store CO 2 in refrigerated tanks at 300 psi and 0°F. �e conventional breakpoint between high- and low-pressure systems is based on the amount of CO 2 required for protection and the space occupied by the cylinders. Typically this is 2,000 pounds of carbon Figure 14-1 High-Pressure Carbon Dioxide Cylinder Arrangement dioxide. Due to energy conservation, high-pressure systems that do not require refrigeration are used in larger systems. �e space occupied by the cylinders is the limiting criteria. A CO2 system may be controlled by either an automatic pneumatic or heat-actuated detector (HAD). Detectors may be either electrical or mechanical. For manual operation, a pull cable is used in a mechanical system, a push button is used in an electrical system, and plant or bottled air is used in a pneumatic system. Manual emergency actuation is used if the automatic operation fails. When installing a carbon dioxide system, the following points should be considered: u High-pressure cylinders must be stored at temperatures of no more than 120°F and no less than 32°F. u �e distribution piping must be steel. For high-pressure systems of ¾ inch and less, use Schedule 40; for 1 inch and larger, use Schedule 80 with malleable and forged-steel fittings. For low-pressure piping, check the required pipe schedule with National Fire Protection Association (NFPA) standards. u Valves and nozzles must be furnished by the vendor and be UL Listed.
System Applications Types of carbon dioxide system applications include the following:
Chapter 14: Carbon Dioxide Systems
97
u
Total flooding in enclosed spaces, such as within electrical equipment, electrical closets, or specially designed enclosures that surround a hazard: In such cases, the CO 2 system includes a fixed supply, piping, and nozzles. u Local application where the hazard can be isolated and CO 2 is applied directly on the burning material: Such a system includes a fixed supply, piping, and nozzles. System design is based on the area to be protected, nozzle design, optimum flow rates, and discharge time. �e total quantity can be calculated as follows:
Total quantity = Nozzle discharge rate x Number of nozzles x Discharge time Note: High-pressure cylinders use a discharge time of +30 seconds. For storage capacity, consult the vendor. u Standpipe and handheld hoses to be directed on burning surfaces: �e supply is discharged through hoses located on reels or racks, preferably laid out so two hoses can reach the same spot simultaneously (estimate two minutes at 500 pounds per minute, or 1,000 pounds of CO2). Note: A 200-foot limitation on the supply line may be extended with a bleeder, which simultaneously opens and closes a valve provided with a timer. u Mobile systems, usually in which twin cylinders are manifolded together and installed on a dolly: Such a system is wheeled to an area where a fire is burning. �e usual application is in parking garages. u Portable fire extinguishers filled with carbon dioxide Examples of CO2 concentrations for deep-seated fires are: u For cable insulation: 50 percent u For dust-filled areas: 75 percent Figure 14-2 summarizes carbon dioxide applications.
Advantages and Disadvantages �e advantages of carbon dioxide as an extinguisher are as follows: u Provides some cooling (minor) u Smothers fires u Leaves no residue aer discharge u Is a gas and has the capability to penetrate and spread �e disadvantages of carbon dioxide as an extinguisher are as follows: u Hazardous to personnel in the area protected u Needs enclosure for best results u Finite supply (vs. water) u Fire may reflash (to suppress and/or prevent reflash, provide a double-shot reserve) CO2 Applications Total flooding Surface fires (oneDeep-seated fires minute discharge, (seven-minute no holding period maximum discharge,* 20-minute holding period
Local application Rate of application determined by area
Rate of application determined by volume
*30 percent concentration within two minutes
Figure 14-2 Summary of Carbon Dioxide Applications
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Fire Protection Systems
ALARMS AND EVACUATION Oxygen deficiency and decreased visibility are both concerns when carbon dioxide is used. For these reasons, it is important to establish an alarm system and evacuation procedure for a CO2 extinguishing system. �e three alarm steps in CO 2 operation are initial, evacuation, and discharge. Each alarm has a distinctive tone; for an effective evacuation, alarm drills are required so the occupants become familiar with the distinctive signals as well as evacuation procedures. When CO2 is released, auxiliary switches operated by either cylinder pressure or an electronic panel may simultaneously cut off fuel (close a gas-supply valve), close dampers, or shut off fans to cut the supply of fresh oxygen, as well as set off alarms, close fire doors, and/or shut down operating equipment. An area protected by CO2 must have warning signs, such as one of the following: u Warning: Carbon dioxide gas is discharged when alarm operates. Vacate immediately. u Warning: Carbon dioxide gas is discharged when alarm operates. Do not enter until ventilated. u Warning: Carbon dioxide discharged into a nearby space may collect here. When alarm operates, vacate immediately. u Warning: Actuation of this device will cause carbon dioxide to discharge. Before activating, be sure personnel are clear of the area. In addition to signs, Occupational Safety and Health Administration (OSHA) regulations require CO2 discharge delays, breathing apparatus available to personnel entering the room (aer the fire is out), and accessible, well-marked exits. SPECIFICATIONS �e engineer should write a specification with the idea that specialized, engineered equipment will be purchased from a vendor. Specifications must include: u Description of the risk (hazard) u Type of system desired (low or high pressure) u Type of activation desired (manual and/or automatic) u Opening closures to be released or activated (door fans, etc.) �e engineer also must show the desired route of piping, but not include sizes. Vendor drawings, together with calculations, shall be submitted for approval to the authority having jurisdiction (AHJ) and the owner�s fire insurance underwriter. For final approval aer installation, a puff test is usually used; however, the puff CO 2 discharge might not be permitted for environmental reasons. In this case, a harmless (inert) gas is used to test the system. CYLINDERS AND SCALES In a carbon dioxide system, high-pressure cylinders are sometimes located on a scale, which is normally inoperable unless lied into position. Cylinders may last up to 12 years before being recharged. Two banks of CO2 are kept in storage for a double shot. One of the two banks of cylinders is a reserve. A cylinder�s weight must be checked every six months. If during this interval a cylinder loses 10 percent of its weight, it must be replaced with a new one. Whatever the arrangement, routine maintenance should include storage area cleanliness. Another part of routine maintenance is to ensure that all equipment is ready for proper operation when needed.
Chapter 14: Carbon Dioxide Systems
99
PIPE SIZING CALCULATIONS When carbon dioxide gas is discharged, the pressure drops, a vapor is formed, and CO 2 volume increases, as does friction in pipes and fittings. Soware is available that takes all of these factors into consideration and can be used when performing pipe sizing calculations. Pipe sizing shall be done by the CO 2 manufacturer. �e designer shall calculate the amount needed and select the system type (high or low pressure). Example 14-1
Perform calculations for a total-flooding system. �e area in which this system will be installed contains flammable materials. Other specifications are as follows: u Space volume: 2,000 cubic feet u Type of combustible: Gasoline u Ventilation openings: 20 square feet From Table 14-1, the design concentration of CO 2 can be found. For this installation, it is 34 percent. From Table 14-2 it is possible to determine the volume factor. For this particular installation, the room has a volume of 2,000 cubic feet. Table 14-2 shows that between 1,601 cubic feet and 4,500 cubic feet, the requirement is 18 cubic feet per pound of CO2. �erefore:
2,000 ft3/18 ft3 = 111 lbs CO2 required Table 14-1 Minimum Carbon Dioxide Concentrations for Extinguishment Material
Acetylene Acetone Aviation gas, grades 115/145 Benzol, Benzene
Theoretical Minimum Minimum CO2 Design CO2 Concentration, Concentration, % %
55 27
66 34
30
36
31
37
Butadiene
34
41
Butane Butane – I
28 31
34 37
Carbon disulfide
60
72
Carbon monoxide Coal or natural gas Cyclopropane Diethyl ether Dimethyl other
53 31 31 33 33
64 37 37 40 40
Dow therm
38
46
Ethane
33
40
Ethyl alcohol Ethyl ether Ethylene Ethylene dichloride
36 38 41 21
43 46 49 34
Ethylene oxide
44
53
Material
Gasoline Hexane Higher paraffin hydrocarbons Hydrogen Hydrogen sulfide Isobutane Isobutylene Isobutylene formate JP-4 Kerosene Methane Methyl acetate Methyl alcohol Methyl butane –I Methyl ethyl ketone Methyl formate Pentane Propane Propylene Quench, lube oils
Theoretical Minimum Minimum CO2 Design CO2 Concentration, Concentration, % %
28 29
34 35
28
34
62
75
30
36
30 26
36 34
26
34
30 28 25 29 33
36 34 34 35 40
30
36
33
40
32 29 30 30
39 35 36 36
28
34
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Fire Protection Systems
It is necessary to account for leaks Table 14-2 Flooding Factors that may occur through openings. Volume of Space, Volume Factor Calculated Quantity, 3 3 3 ft incl. lb, no less than For the purposes of this example, ft /lb CO2 lb CO2/ft use a quantity of 1 pound of CO 2 Up to 140 14 0.072 — 141 to 500 15 0.067 10 per square foot to determine the 501 to 1,600 16 0.063 35 required additional amount of CO 2 1,601 to 4,500 18 0.056 100 needed to compensate for leaks 20 0.050 250 through openings. �erefore, for a 4,501 to 50,000 More than 50,000 22 0.046 2,500 20-square-foot opening:
20 ft2 x 1 lb/ft2 = 20 lbs �e amount depends on whether the opening remains open, has a large amount of leakage, etc. For openings that are not to be closed, a calculated additional amount of CO 2 must be provided. For this example, the total amount of CO 2 required is 131 pounds (111 + 20). Two shots are recommended, so use 300 pounds of CO2 (131 x 2 = 262 pounds and round up), or four cylinders at 75 pounds each. �is will include two cylinders for the first shot and two for the reserve shot.
Pressure-Relief Venting Formula Now that the total amount of CO 2 has been determined, it is necessary to calculate the size requirement for the overpressure vent openings. For very tight spaces, overpressure openings must be calculated based on a pressure-relief venting formula, which is as follows: Equation 15-1
X=
Q 1.3√p
where
X = Free area, in.2 Q = Calculated carbon dioxide flow rate, lb/min p = Allowable strength of enclosure, lb/ft2 Again, this should be calculated with the manufacturer representative�s help. Since the design requirement for this example is not more than 34 percent concentration, no correction factor is required for the basic quantity. If the concentration is more than 34 percent, the quantity of CO2 required is increased by a factor of 1 to 4 (see Figure 14-3). The pressure-relief venting factor applies to openings and is also called the correction factor. �e amount of CO2 discharged must be increased when the normal temperature of the protected space is above 200°F. Example 14-2
Size a carbon dioxide system for an electrical equipment system with two adjacent electrical switch-gear rooms of 50,400 cubic feet and 58,800 cubic feet and 50-square-foot openings.
Figure 14-3 CO2 Concentration Conversion Factors
Chapter 14: Carbon Dioxide Systems
To find the preliminary estimate of CO2 required, use the largest risk of 58,800 cubic feet and divide by the appropriate flooding factor, which can be found in Table 14-3. In this case, since the space is more than 2,000 cubic feet, the factor is 12 cubic feet per pound of CO2. �erefore:
58,800 ft2/(12 ft3/lb CO2) = 4,900 lbs of CO2 required
101
Table 14-3 Flooding Factors for Specific Hazards Design Concentration, %
ft3/lb CO2
50
10
50
12
65
8
75
6
lb CO2/ft3
Specific Hazard
Dry electrical hazards in general (spaces 0 to 2,000 ft3) 0.083, 200- Dry electrical hazards in spaces lb min. greater than 2,000 ft3 Record (bulk paper) storage, 0.125 ducts, covered trenches Fur storage vaults, dust 0.166 collectors 0.100
Source: NFPA 12
Use a factor of 2 pounds of CO 2 per square foot for openings:
2 lb CO2/ft2 x 50 ft2 = 100 lbs of additional CO2 required �e final amount of CO 2 required is 5,000 pounds (4,900 + 100). A single shot would require 5,000 pounds, and a double shot would require 10,000 pounds. For a double-shot system (remember that 2,000 pounds = 1 ton), use a 5-ton, low-pressure, refrigerated tank. Using the number of cylinders required for a high-pressure system would not be a practical solution. For gas discharge, the practical maximum distance between the storage point and the discharge point is 300 feet (for a low-pressure system), and the absolute maximum distance is 400 feet. At distances beyond these points, separate systems must be installed, with each system closer to the hazard protected. For rotating electrical equipment, the air volume of the interior equipment to be protected must be obtained from the equipment manufacturer.
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Dry and Wet Chemicals
15
Dry and wet chemical extinguishing systems are primarily used on flammable liquid (Class B) fires, and dry chemicals also can be used for fires involving energized electrical equipment (Class C). Dry chemical systems are typically found in industrial, marine, and aircra applications. Wet chemical systems commonly provide fire protection for commercial kitchen hoods, ducts, and appliances. National Fire Protection Association (NFPA) standards mandate the provision of a Class K portable fire extinguisher in locations with either a dry or wet chemical system in case the fire spreads outside the protected area.
DRY CHEMICAL EXTINGUISHING SYSTEMS Dry chemicals are most effective and most oen used on surface fires, especially on flammable and combustible liquids, and they can be applied using various methods , including portable extinguishers, hand hose-line systems, or fixed (local or total-flooding) systems. Dry chemicals are particularly suited for outdoor environments where concerns about freezing prevent the installation of water-based systems. �e minimum requirements for the design, installation, maintenance, and testing of dry chemical extinguishing systems can be found in NFPA 17: Standard for Dry Chemical Extinguishing Systems and UL 1254: Standard for Pre-Engineered Dry Chemical Extinguishing System Units. Another applicable standard is NFPA 33: Standard for Spray Application Using Flammable or Combustible Materials. Dry Chemical Agents A dry chemical system utilizes a dry powder mixture as the fire-extinguishing agent. �e five basic varieties of dry chemical extinguishing agents are borax and sodium bicarbonate, sodium bicarbonate, urea-potassium bicarbonate, monoammonium phosphate base, and potassium bicarbonate (commonly referred to as Purple K). Dry chemicals are effective in extinguishing fires involving flammable and combustible liquids and gases, combustible solids, energized electrical hazards, and flash surface fires. Dry chemicals can be used to extinguish ordinary combustibles (Class A), but they are not the most efficient or effective means of suppression for this hazard. Dry chemicals are not effective in extinguishing deep-seated fires due to the nature of the chemical and its inability to penetrate the object�s surface. Twin-agent units using dry chemicals for early flame knockdown, followed by a foam application to prevent re-flash, are becoming a popular means of fire suppression in the petroleum, petrochemical, marine, natural gas, and aviation industries.
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Fire Protection Systems
How Dry Chemicals Extinguish Fire Dry chemicals work by breaking the chain reaction of combustion. When introduced directly into the fire area, dry chemicals cause almost immediate extinguishment by suppressing the fire via saponification, a method in which a thin foam barrier forms between the fuel and the oxygen source, depriving the fire of oxygen and shielding the fuel from hot gas layer radiation. While dry chemicals provide rapid flame-suppressing capabilities, the subsequent cleanup is a disadvantage. Cleanup may entail a multi-pronged approach, including dry powder vacuuming, surface washdown, and scrubbing with neutralizing elements. When wet or le in a high-humidity environment, dry chemicals may be corrosive to surfaces s ensitive to mildly acidic or alkaline materials. System Types Local Application Dry chemicals can be discharged by handheld extinguishers or wheeled portable equipment in local applications where the hazard is not enclosed or where the enclosure does not form an effective fire boundary. �is includes such areas as temporary/open spray booths, chemical mixing areas, and small oil-filled transformers. �e hazardous area includes all locations that are or may become coated by the flammable liquid, including those areas subject to spillage, leakage, dripping, or splashing. Chemical application may be from the side, overhead, or a combination of both. �e amount of extinguishing agent depends on the hazardous area or the volume of the hazardous object. Handheld Hose Lines A handheld hose-line system consists of a hose and a nozzle connected to a dry chemical supply by direct connection to the storage container or by fixed piping. One or more hose reels can be supplied by the same chemical supply. �e capacity of the unit must be capable of maintaining flow through the hose line for a minimum of 30 seconds. Total Flooding Dry chemical systems also may be total flooding. �e total-flooding system consists of a predetermined supply of dry chemical permanently connected to a fixed discharge piping system (typically utilizing galvanized pipe), with fixed nozzles discharging into an enclosed space or an enclosure around a hazard. Upon activation of the system by a heat detector or manual actuation, expellant gas is discharged into the storage container, and dry chemical is propelled through the system�s nozzles. A fixed system providing total flooding must be capable of providing the design concentration in all parts of the hazardous area within 30 seconds. Openings such as doors and room ventilation systems must be coordinated to automatically close upon system discharge. Openings not capable of being closed must be limited to less than 15 percent of the total enclosure area; if these non-closing openings exceed 15 percent, a local application system is more effective. A total-flooding system may be either of the following: u Engineered: �ese systems are designed based on known factors of chemical flow, pressure, friction losses, and pressure drops. Detection and activation are by automatic operation using electric, electronic, or mechanical detection and discharge. Many au-
Chapter 15: Dry and Wet Chemicals
105
thorities require a full discharge test aer installation for verification of the effectiveness of such a system or require a room air pressure test. u Pre-engineered: �ese systems have been fire-tested for a listing with a recognized laboratory. �e installation must be in compliance with the limitations imposed by the manufacturer�s instructions regarding installation for specific hazard types and sizes, pipe sizes, pipe lengths, number and types of fittings, number and types of nozzles, and types and quantities of chemicals to be used. Most pre-engineered systems are designed for automatic operation, using electric, electronic, or mechanical detection and discharge. A manual pull station is required to be installed at an exit.
Storage and Maintenance Dry chemical powders are typically stored in pressurized cylinders, with an accompanying cylinder of carbon dioxide or nitrogen for use as an expellant gas. Dry chemical cylinders must be located in close proximity to the protected area due to the large amount of friction loss experienced by the dry chemical�s flow through the discharge piping. Dry powders should be stored in an environment between -40°F and 120°F, and they are stable up to approximately 130°F. Operating temperatures are primarily limited by the expellant gas. �e container in which the dry chemical is stored should be tightly closed and kept in a dry location to prevent the absorption of moisture. If any caking occurs due to moisture, the dry chemical must be discarded. Dry chemicals of different compositions shall not be stored in the same container. In general, all dry chemical powder systems should be inspected annually. Hand hoseline systems may be inspected more frequently depending on the location and climate. WET CHEMICAL EXTINGUISHING SYSTEMS Wet chemical agents are the only agents listed to suppress fires in commercial cooking appliances and equipment, such as deep-fat fryers, griddles, range tops, broilers, kitchen hoods, plenums, exhaust ducts, and grease filters. According to the National Association of Fire Equipment Distributors, pre-engineered wet chemical fire suppression systems are 95 percent successful in suppressing kitchen cooking hazard fires. �e minimum requirements for the design, installation, maintenance, and testing of wet chemical extinguishing systems can be found in NFPA 17A: Standard for Wet Chemical Extinguishing Systems and NFPA 96: Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations . Wet chemical systems are performance tested under the guidelines of UL 300: Fire Testing of Fire Extinguishing Systems for Protection of Commercial Cooking Equipment. Wet Chemical Agents Wet chemical fire-extinguishing agents consist of a potassium carbonate, potassium acetate, or potassium citrate-based solution of organic or inorganic salts mixed with water to form a liquid alkaline solution that is typically discharged as fine droplets though a piping and nozzle system using expellant gas. Wet chemicals will react with any water-reactive metals (typically Class D fires), energized electrical equipment, and any other water-sensitive materials. Wet chemicals are typically nontoxic and non-carcinogenic in nature, although slight skin and respiratory irritation may occur with prolonged exposure.
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Fire Protection Systems
How Wet Chemicals Extinguish Fires When the wet chemical extinguishing agent is sprayed on a grease fire, it interacts immediately with the grease (saponification) to form a blanket of foam over the fuel�s surface, preventing further contact with oxygen (smothering) and to cool the fuel source below its combustion temperature. �e fine droplets also cool the surrounding air via vaporization and prevent splashing. For kitchen cooking hazard fires, wet chemical fire suppression systems are preferred over dry chemical systems because they provide faster flame knockdown, and the fine spray helps prevent re-ignition aer the discharge is complete. Cleanup is another benefit: the wet chemical can be easily removed from surfaces using a cloth. System Description Wet chemicals are typically applied via a pre-engineered local application system consisting of an activation gas tank, agent tank, distribution piping, discharge nozzles, a releasing device, fuse link or heat detector, manual pull station, and gas/electric shutoff device, with predetermined flow rates, nozzle pressures, and quantities of agent required. Wet chemicals are usually stored in cylinders adjacent to the hazard and are activated by either manual (pull station) or automatic (fuse link or heat detector) means. When the system is actuated, the seal on the gas tank opens, and the gas flows to the agent tank to force the wet chemical through the distribution piping and nozzles. A typical wet chemical system discharges 3 to 4 gallons of agent in approximately 30 seconds.
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Clean Agents
16
Halon compounds are composed of hydrocarbon molecules in which one or more of the hydrogen atoms have been replaced with bromine, fluorine, or chlorine. Originally discovered and developed in the 1960s, halons were utilized as a gaseous fire suppression agent that could be effectively employed in areas that could not withstand the discharge of water, such as computer rooms, telecommunications rooms, flammable liquid storage areas, and switchgear rooms. Halons possess extremely low toxicity levels, are electrically inert, and do not empty the room of oxygen, allowing them to be deployed in a space where personnel could still be present (unlike carbon dioxide, where a suffocation potential exists). Aer discharge, the altered hydrogen compound could no longer ignite and le little to no residue. �e one major disadvantage of halons is their environmental impact: they are severely damaging to the ozone layer and can reside in the atmosphere for a significant period. �e Montreal Protocol (1987) restricted the creation of new chlorofluorocarbons, and in 1994 new production of halons was stopped, practically eliminating the use of halons in fire suppression systems in 197 countries including Canada and the United States. A small secondary market has arisen to reclaim discharged halons and maintain existing systems using stockpiles of halon gases, but overall, most halon systems have been decommissioned, are slated for decommissioning, or have been retrofitted with a clean agent equivalent.
DEVELOPMENT OF CLEAN AGENTS Clean agents were developed to replicate the effectiveness of halons but without the negative environmental impacts. National Fire Protection Association (NFPA) 2001: Standard on Clean Agent Fire Extinguishing Systems defines a clean agent as an �electrically nonconducting, volatile, or gaseous fire extinguishant that does not leave a residue upon evaporation.� Clean agents must be liquefied gas or quickly convert to gas upon discharge. Most, if not all, clean agents can be stored and discharged from typical total-flooding halon system hardware. Generally, clean agents are less efficient per pound than halon systems, requiring more stored agent (and subsequent storage area) to produce the same extinguishment results. �e types, requirements, and approvals for clean agents are outlined in: u NFPA 2001 u UL 2127: Standard for Inert Gas Clean Agent Extinguishing System Units u UL 2166: Standard for Halocarbon Clean Agent Extinguishing System Units According to NFPA 2001, clean agents should not be used on the following materials: u Chemicals capable of rapid oxidation in the absence of air (such as gunpowder) u Reactive metals including lithium, sodium, potassium, magnesium, and uranium u Metal hydrides u Chemicals capable of undergoing auto-thermal decomposition, like organic peroxides and hydrazine
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Fire Protection Systems
TYPES OF CLEAN AGENTS Two types of products fall under the clean agent definition: halocarbon compound replacements and inert gas agents. Both types have advantages and disadvantages. Halocarbon replacements consist of halogenated agents incorporating such compounds as carbon, hydrogen, fluorine, chlorine, and iodine. Halocarbon replacements extinguish fires through a variety of methods, each specific to the chemicals used within the agent, but predominately though chemical suppression. Halocarbon agents are engineered and man-made products (unlike inert gases) that are stored as a liquid. Inert gases consist of an electrically nonconductive gaseous mixture composed of argon, nitrogen, or other gases that do not support a flame reaction. �ese gases extinguish a fire by cooling the surrounding flame. �ey do not break down in the fire to produce harmful gases or other dangerous decomposition products. Unlike carbon dioxide, they can be discharged into a space without causing occupant suffocation (although occupant evacuation is still required). Inert gases require a large quantity of gas to be effective, mandating a very large (comparatively) storage area. �e protected space must also have pressure-relief venting engineered and installed to prevent overpressurization and damage to the room.
EXTINGUISHING METHODS Table 16-1 outlines the well-known agents by trade name and the primary extinguishing mechanism of each agent. Table 16-1 Clean Agent Information Chemical Agent
Trade Name
Agent Type
Extinguishing Mechanism
HFC-227ea
FM-200
Halocarbon replacement
Chemical suppression
HFC-125
FE-25, ECARO
Halocarbon replacement
Chemical suppression
HFC-23
FE-13
Halocarbon replacement
Chemical suppression
FK-5-1-12
NOVEC 1230/SAPPHIRE
Halocarbon replacement
Evaporative cooling
IG-541
Inergen
Inert gas
Flame cooling
IG-55
Argonite
Inert gas
Flame cooling
IG-100
Nitrogen
Inert gas
Flame cooling
Chemical Suppression �is is the principal extinguishment method of halons, and the original clean agent replacement gases strove to mirror this mechanism. Most of these agents use fluorinated compounds (versus the brominated compounds in halons) that bind with flame radicals, thereby interrupting the chemical chain reaction of the fire. �ese compounds work in a similar manner as halons but are less efficient because, unlike bromine, fluorine atoms cannot be continually recycled in the combustion process; thus, more agent needs to be discharged in the space to reach the same extinguishment effectiveness.
Evaporative Cooling at the Flame’s Reaction Zone �is method of extinguishment is a more recent development in clean agents. It mirrors the primary principle of sprinkler systems without the use of water. �e clean agent reduces the flame�s temperature below the minimum temperature required to maintain reaction rates due to the high heat capacity of the chemicals during decomposition. �at is, the chemicals use heat from the space to decompose, thereby cooling the surrounding environment.
Chapter 16: Clean Agents
Flame Cooling �is is the primary extinguishing method for inert gases. �ese agents suppress fires by cooling the flame�s temperature below the combustion threshold. Cooling of the flame is a two-pronged attack: the oxygen content in the room is reduced to the limits of combustion (without affecting overall life safety) while the heat capacity of the surrounding atmosphere is raised.
ENVIRONMENTAL IMPACT �e three main factors to consider when evaluating the environmental impact of various agents are ozone depletion potential (ODP), global warming potential (GWP), and atmospheric lifetime. When designing a clean agent system, consideration should be given to the chemicals� impact on the environment and green building certification goals. �e first consideration is how the chosen chemical impacts the ozone layer. Ozone is a product created when ultraviolet (UV) light breaks down oxygen (O 2) into two separate oxygen molecules, which combine with existing oxygen to create ozone (O 3). �e process occurs naturally in the stratosphere and provides a shield against harmful UVB light from the sun. Halons and other halocarbons containing chlorine or bromine have been demonstrated to destroy ozone in the stratosphere. �e valuation of this destruction potential is not a measure of the exact amount of ozone destroyed by the chemical, but rather it is the amount of ozone destroyed as compared to an arbitrary standard—in this case, the chosen chemical is CFC-11, which is assigned an ozone depletion potential of 1. Halon 1301 has an ODP of 12, meaning it will destroy 12 times as much ozone as CFC-11 on a mass-per-mass basis. FM-200 has an ODP of 0, meaning it will not destroy any ozone in the stratosphere. �e second factor is the global warming potential of the agent. �e atmosphere is primarily composed of nitrogen and oxygen, but trace elements of carbon dioxide, water vapor, and other gases lead to the capture of radiant heat from the sun, causing elevated temperatures through the greenhouse effect. Certain elements in the atmosphere are more effective at retaining heat and therefore cause the air to stay warmer. To quantify the greenhouse effect, the concept of radiative forcing was developed. Radiative forcing is anything that will cause the troposphere to change, causing the radiation into and out of the atmosphere to unbalance. Any condition that results in a positive radiative forcing value will cause a rise in the average temperature, whereas a negative radiative forcing value will cause a drop in atmospheric temperature. A scale was developed by the Intergovernmental Panel on Climate Change to quantify the global warming change, called the global warming potential, which is the cumulative effect of radiative forcing between the present and a future time caused by a unit mass of a compound as compared to the same unit mass release of carbon dioxide. �e common reference periods are typically 20 years, 100 years, and 500 years. For example, a 100-year GWP of FM-200 is 3,500, meaning that 1 pound of FM-200 will cause as much global warming as 3,500 pounds of released carbon dioxide. �e final consideration in selecting a clean agent is the atmospheric lifetime of the chemical. �e atmospheric lifetime of a chemical is simply the time in which the chemical will reside in the stratosphere and have an effect on GWP and ODP. �e values are measured in years. For example, Halon 1301 has an atmospheric lifetime of 65 years, meaning that it will stay in the atmosphere (at an appreciable quantity) for 65 years, causing ozone depletion and global warming (cumulative effect).
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Fire Protection Systems
Table 16-2 compares the environmental effects of several common compounds.
SAFETY
Table 16-2 Chemical Impacts on the Environment Property
Halon 1301
FM-200
FE-25
NOVEC 1230
Ozone depletion potential
12
0
0
0
Global warming
6,900 3,500 3,400 1 �e two levels that are particu- potential, 100 years larly important when designing Atmospheric lifetime, 65 33 29 0.014 years clean agent systems are the NOAEL and LOAEL. NOAEL, or no-observed-adverse-effect level, is the highest concentration at which no harmful toxicological or physiological effects have been observed from exposure to the agent. LOAEL, or lowest-observed-adverse-effect level, is the lowest concentration at which an adverse effect (toxicological or physiological) has been observed from exposure to an agent. All clean agent systems should be engineered to discharge enough agent to meet the minimum design criteria for the hazard being suppressed, yet remain below the NOAEL limit of the particular chemical to retain a chemically safe environment within the enclosure. While they are safer than carbon dioxide, unnecessary exposure to any halocarbon should be avoided, with pre-discharge alarms and time delays implemented to warn occupants of discharge and give them a chance to escape the area. Inert gas agents are not toxic and therefore do not have a NOAEL design limit. However, they do reduce the oxygen concentration during discharge to a point that could create an asphyxiation hazard. Inert gas systems typically decrease the oxygen concentration in the enclosure to 11 to 13 percent to suffocate combustion within the room. Human exposure to such a low oxygen concentration should not exceed five minutes. �e concentration of the system corresponds to the total oxygen amount in the room (based on the enclosure volume) and should be coordinated to ensure that oxygen levels do not dip below 10 percent (unless the room is not normally occupied) and that any exposure can be limited to 30 seconds. All clean agents form more decomposition products than Halon 1301; therefore, they have the potential to have negative health effects on occupants. Depending on the exposure time and the concentration of the clean agent within an enclosure, clean agents can cause eye and nasal irritation, upper respiratory tract irritation, and tissue surface irritation. Prolonged exposure to halocarbons can trigger cardiac arrhythmia. �e varied effects of inert gases could be so pronounced as to impair escape. �erefore, all clean agent discharge areas should be equipped with discharge signs, strobes, and exit signs to facilitate rapid egress. Table 16-3 shows the minimum design concentrations required to extinguish Class A and Class C fires, as well as the NOAEL for each chemical.
Table 16-3 Minimum Design Concentrations for Five-Minute Exposure Clean Agent
Class A Minimum Design Concentration, %
Class C Minimum Design Concentration, %
NOAEL, %
FM-200
6.7
7
9
FE-25/ECARO
8.7
9
11.5
NOVEC-1230
4.5
4.7
10
Inergen
34.2
38.5
43 design concentration (12 oxygen concentration)
Argonite
37.9
42.7
43 design concentration (12 oxygen concentration)
Chapter 16: Clean Agents
SYSTEM DESIGN Similar to carbon dioxide and chemical systems, clean agents can be designed as a total-flooding system or for local application. Total-flooding systems are an engineered assembly consisting of a calculated quantity of agent discharging into a tight, fully enclosed space designed to retain and concentrate the agent. Local application systems are employed to suppress hazards that are not enclosed or where the enclosure does not form an effective fire boundary, such as transformers, spray booths, chemical hoods, etc. Due to the gaseous nature of clean agent systems, they are much more effective when discharged into an area that will prevent rapid ventilation and evaporation of the gas, allowing the concentration to quickly reach extinguishment levels. While halons were used in both local application and total-flooding systems, the decreased effectiveness of alternative clean agent systems essentially limits them to total-flooding applications. If local application is desired, an alternative system such as water mist or dry chemical should be considered. Typical applications for clean agents include data centers/IT facilities, telecommunications rooms, control rooms, and record storage/archive areas.
Design Procedure �e process of designing a total-flooding clean agent system involves the following steps: 1. Determine the hazard area to be protected and the volume of that area. 2. Determine the agent to use. 3. Define the hazard and determine the appropriate design concentration for the space. 4. Calculate the total quantity of agent required. 5. Design the maximum discharge time. 6. Design the agent storage location, piping distribution network, and nozzle location/type. 7. Establish the piping material and thickness rating for the chosen agent. 8. Engineer the detection system for agent release, including detector types, the panel, detector layouts, and the interface with the releasing system. 9. Evaluate the pressurization potential of the hazard area to determine whether relief venting will be required. 10. Analyze compartments for leakage and seal the hazard area. A more detailed description of the implementation of these steps follows. Step 1. �e first step is to concretely define the area to be protected by the clean agent system. As these systems are costly and require extra equipment and preparation, it is important to accurately identify critical protection areas versus estimating a general location/enclosure. Once the protected area is defined, a general room volume needs to be determined to accurately size the system. Step 2. Selection of the agent to use is based on many factors, including room hazards, enclosure integrity, owner requirements (e.g., environmental preferences), effectiveness/ required concentration amount based on the hazard size, and project budget. Step 3. �e design concentration should be established through calculation methods available in NFPA 2001 and should be appropriate for the hazard protection. General minimum design concentrations are outlined in Table 16-2. Step 4. �e total agent quantity available affects both the design concentration and the discharge time. General equations to estimate the required agent quantity for both halocarbon clean agents and inert gases are available. �e equations require the agent type and specific weight, the volume of the protected space, and the design concentration
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Fire Protection Systems
of the agent. �ese equations do not estimate or take into account enclosure leakage. For halocarbons, use Equation 16-1: Equation 16-1
w=
V C x S 100 – C
where
w = Specific weight of agent required V = Net volume of protected space C = Design concentration percentage S = Specific volume S can be defined using the following equation and Table 16-4 to estimate the required discharge volume based on the specific volume constants. Equation 16-2
S = K1 + K2(T)
Use Equation 16-3 for inert gases. Equation 16-3
X = 2.303 where
V 100 log ( )V S 100 – C s
Table 16-4 K Values for Equation 16-2 Agent
K1
K2
FE-13
4.730
0.0106
FE-25
2.722
0.0063
FM-200
1.879
0.0046
NOVEC 1230
0.986
0.0024
Argonite
9.881
0.0214
Inergen 9.858 0.0214 X = Volume of inert gas at 70°F Source: NFPA Handbook, Chapter 6 Vs = Specific volume at 70°F V = Net protected hazard volume S = Specific volume Step 5. Halocarbon clean agent systems are limited to a 10-second discharge, defined as the point when all liquid agent has cleared the final nozzle. Additional vaporized agent may still leave the piping due to the uncontrolled gaseous nature of the agent. Inert gases are generally at a 60-second discharge time, but that may be increased if the design concentration requires for certain applications. Step 6. �e agent is typically stored within the protected enclosure or in a separately isolated and protected room close to the protected area. �e storage location will depend on the type of clean agent or inert gas being used, based on discharge time constraints, pressure piping losses, and the energy required to drive the clean agent. Individual agent characteristics and requirements must be considered for location and distance constraints. Step 7. �e chosen piping is specific to each agent�s distribution system. �e distribution piping must be engineered to mechanically control the agent discharge time, maintain adequate nozzle flow and pressure to ensure agent distribution, and deliver both uniform and sufficient agent quantity to every area of the protected enclosure. Each clean agent manufacturer typically has proprietary soware that can accurately size a designed piping system and a soware user certification program. Step 8. �e detection system is an important part of a clean agent system. �e detection and alarm system is responsible for detecting and confirming a fire, sounding the pre-discharge alarms, and rapidly actuating the system. Step 9. �e near-instantaneous release of agent into an enclosure causes rapid changes to the compartment�s pressure. Depending on the agent and the rate of discharge, the pressure
Chapter 16: Clean Agents
113
of the compartment can fluctuate between a negative and a positive value due to the cooling of the compartment and the vaporization of the agent. �is effect is particularly notable with inert gases, as the discharged gas will rapidly expand in the space. Calculating the required open venting area is part of the design process for inert gas systems. �e pressure-relief vent (or vents) must be positioned at a location, typically higher in the compartment, to prevent heavier-than-air agent from escaping during the discharge/settling period. Step 10. �e compartment should be analyzed for leakage and sealed for integrity to prevent agent loss during discharge and to ensure that the design concentration is maintained throughout the required hold time. In conjunction with the fire alarm�s activation (and during the pre-discharge period, prior to system activation), the compartment�s openings (doors, windows, vent openings, cable openings) must be automatically closed. All openings must be secured before agent release to ensure that adequate concentrations of the clean agent remain in the compartment during the design period. A door fan test (room integrity test) and leakage calculations are performed by certified personnel to simulate a worst-case leakage scenario in the space and to ensure that an adequate concentration of the agent is maintained within the space during and aer discharge. Door fan test methods are standardized by ASTM E779, ASTM E1827, and CAN/CGSB-149.10-M86. Leakage calculations are performed using certified computer soware operated by certified users. Leaks are detected by a smoke pencil test and sealed off using standard construction techniques. Door fan testing is considered a conservative approach, and if acceptable to the authority having jurisdiction, a witnessed detailed leak inspection might be a substitute.
CONCLUSIONS/COMPARISONS Table 16-5 summarizes the various positive and negative aspects of clean agent fire suppression chemicals. It also outlines the possibility of future regulation within the industry; although no formal talks have occurred, some speculate that halocarbon-based extinguishing chemicals may be further regulated or banned based on health or environmental impact. �e chart is for comparison purposes only and may vary significantly based on market factors, local labor rates, and building type. Table 16-5 Clean Agent Comparison Table Property
Halon 1301
Transport*
Class 2.2
Environmental impact
High
Low
Occupant hazard and system safety factor
Low
Cost (compared to halons)
CO2
FM-200
FE-25
NOVEC 1230
Inergen
Argonite
Class 2.2
No regulation if cylinders are not charged with nitrogen/CO 2
Class 2.2
Class 2.2
Medium
Medium
Low
None
None
High
Low
Low
Very low
Low
Low
$
x1.5$
x2$
x2$
x3$
x4$
x4$
Space/storage requirements
Low
Medium
Low
Low
Low
High
High
Future regulation
Banned
None
Possible
Possible
None
None
None
Class 2.2 Class 2.2
*Class 2, Division 2 (or Class 2.2) is a HAZMAT categorization that is applied on all nonflammable, nontoxic gases. These gases exert (in the packaging) an absolute pressure of 40.6 psia or greater at 68°F and are not Division 2.1 (flammable) or 2.3 (toxic) gases.
115
Portable Fire Extinguishers
17
Portable fire extinguishers offer a convenient and easy means of putting out small fires or supplementing fixed fire suppression systems. Portable fire extinguishers are most effective when a fire just begins and people are present in the area. NFPA 10: Standard for Portable Fire Extinguishers details the classification, marking, installation, and maintenance requirements for portable extinguishers. Requirements also can be found in 29 CFR 1910.157 published by the Occupational Safety and Health Administration (OSHA).
CLASSIFICATIONS Portable fire extinguishers are classified based on the type of fire they can extinguish: u Class A extinguishers are used on ordinary combustibles such as wood, paper, and textiles and contain either water or dry chemicals. u Class B extinguishers are used on flammable liquids and gases and contain agents that deprive the fire of oxygen and inhibit the release of combustible vapors. u Class C extinguishers are used on energized electrical equipment fires and contain an electrically nonconductive extinguishing agent. u Class D extinguishers are used on combustible metals, such as sodium, titanium, zirconium, and magnesium and contain an extinguishing medium that does not react with the burning metal. u Class K extinguishers are used on fires involving cooking media (fats, grease, and oils) in commercial kitchens and contain either wet or dry chemicals. e extinguisher is marked with its letter Table 17-1 Portable Fire Extinguisher Classifications and a symbol for easy identification as shown Hazard Symbol Color in Table 17-1. Extinguishers suitable for more Class A Ordinary combustibles Triangle Green than one class of fire should be identified B Flammable liquids Square Red by multiple symbols placed in a horizontal C Live electrical fires Circle Blue sequence. D Flammable metals Star Yellow Class A and Class B extinguishers also carry K Cooking media None None a numerical UL rating to indicate the size of fire an experienced person can put out with the extinguisher. Each A rating is equivalent to 1.25 gallons of water, so an extinguisher marked 5A would be equivalent to 6.25 gallons of water. e B rating is equivalent to the amount of square footage the extinguisher can cover, so an extinguisher marked 10B could cover 10 square feet. Class C and D extinguishers do not have a numerical rating. Class C fires are essentially Class A or B fires involving live electrical equipment, so the rating should be based on the amount of the Class A or Class B component. e effectiveness of Class D extinguishers is described on the faceplate.
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Fire Protection Systems
INSTALLATION Portable fire extinguishers constitute the first line of defense against a fire, so they should be located in strategic locations, including at every exit from a floor or building. A portable fire extinguisher must be conspicuously located, with its top 3 to 5 feet above the floor. Bright markings must draw attention to its location. OSHA requires fire extinguishers to be located based on the class of anticipated fires as well as the size and degree of the hazard. e Table 17-2 Travel Distances to Portable requirement is based on the distance a person Fire Extinguishers must travel to reach a fire extinguisher. See Table Class Travel Distance 17-2 for the placement requirements. A 75 ft or less A plan showing the proposed locations of B 50 ft fire extinguishers must be developed before C Based on appropriate Class A or B hazard installation. is plan must be submitted to the D 75 ft or less authority having jurisdiction for their comment Note: Class K extinguishers have no distance requirement. They are typically placed at the point of possible cooking and/or approval. fire ignition. Source: OSHA 1910.157
MAINTENANCE OSHA 1910.157 requires portable fire extinguishers to be visually inspected monthly to verify the following: u Fire extinguishers are in their assigned places. u Fire extinguishers are not blocked or hidden. u Fire extinguishers are mounted in accordance with NFPA 10. u Pressure gauges show adequate pressure. u Pin and seals are in place. u Fire extinguishers show no visual sign of damage or abuse. u Nozzles are free of blockage. Table 17-3 Hydrostatic Testing Requirements Type of Extinguisher Test Interval, years OSHA 1910.157 also requires Soda acid (stainless steel shell) 5 hydrostatic testing by trained perCartridge-operated, water and/or sonnel according to the schedule 5 antifreeze found in Table 17-3. Stored pressure, water and/or antifreeze 5 To sum up, portable fire extinWetting agent 5 guishers must be: Foam (stainless steel shell) 5 u Properly located and in good Aqueous film-forming foam (AFFF) 5 working condition Loaded stream 5 u Conspicuously located Dry chemical with stainless steel 5 u e proper type for the respective Carbon dioxide 5 combustible material Dry chemical, stored pressure, with mild 12 steel, brazed brass, or aluminum shells u Used when the fire is still small so Dry chemical, cartridge or cylinder the extinguisher will be effective 12 operated, with mild steel shells u Clearly marked for easy identifiDry powder, cartridge or cylinder 12 cation, labeled, tested regularly, operated, with mild steel shells Halon 1211 12 and inspected Halon 1301 Source: OSHA 1910.157
12
INDEX
Index Terms
Links
# “3 times rule”
56
3M Novec 1230 (FK-5-1-12)
33
108
110
113
A absolute pressure
63
AFFF (aqueous film-forming foam)
84
116
AHJ (authorities having jurisdiction)
2–3
18
air handlers
24
air pressure
63
air-pressurized barriers
10
aircraft hangers
29
airports
83
alarm systems
6
analyzing requirements
24
carbon dioxide systems
98
carbon monoxide detection
23
clean agent systems components of
110 24–25
for diesel pump drivers
36
signaling evacuation
30
sprinkler alarms standards
83
54–55 6
testing
21
alcohol liquids
85
23
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25
Index Terms
Links
alcohol-resistant aqueous film-forming foam (AR-AFFF)
84
85
alcohol-resistant film-forming fluoroprotein (AR-FFFP)
84
85
alcohol-resistant fluoroprotein foam (AR-FP)
84
85
ammonia
23
annunciation systems
23
24
antifreeze solutions
22
116
antifreeze sprinkler systems
50
62
application rates (foam)
87
aqueous film-forming foam (AFFF)
84
116
AR-AFF (alcohol-resistant aqueous film-forming foam)
84
85
AR-FFFP (alcohol-resistant film-forming fluoroprotein)
84
85
AR-FP (alcohol-resistant fluoroprotein foam)
84
85
area modifications (sprinkler systems) Argonite (IG-55)
79–80 33
109
113 “around the pump” proportioning Asch Building
86 7–8
ASET (available safe egress time)
23
ASHRAE Guideline 0: The Commissioning Process
19
aspirated foam discharge
86
atmospheric lifetimes
109
atmospheric pressure
63
authorities having jurisdiction
2–3
automatic detection systems
25
automatic doors
14
automatic dry standpipes
43
automatic pump systems
37
18
45
automatic sprinkler systems. See sprinkler systems automatic wet standpipes
43
auxiliary power
24
available safe egress time (ASET)
23
axisymmetric flow
62
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110
Index Terms
Links
B balanced-pressure proportioning systems
86
barriers air pressurization designing into buildings fire-rated walls and doors basis of design (BOD)
battery failures biodegradable foam
10 13–14 5 17
18
20
48
36 87–88
biological oxygen demand
88
blankets
11
BOD (basis of design)
17
18
20
48
BOD (biological oxygen demand)
88
boiling points
83
booster pumps
32
borax
37
103
Boston textile mills
47
brake horsepower
40
breathing apparatus
98
bromine
107
buildings certificates of occupancy construction safety exits
2 14–15 5
fire-safety design green building certification occupancy classifications
19
13–15 109 51–52
remodeling
15
smoke control
10
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19
Index Terms
Links
buildings (Cont.) structural stability Triangle Shirtwaist Fire bulb water mist dispensers
5 7–8 92
C calculations. See formulas and hydraulic calculations carbon
9
11
108
33
95–97
carbon dioxide alarms and evacuation
98
characteristics
95
compared to clean agents
113
concentrations needed for combustibles
99
cylinder storage and scales
98
dry chemical systems and
105
as extinguishing agent
31
fires and
11
installing systems
96
sizing system pipes
99–101
system advantages/disadvantages
97
system specifications
98
testing systems types of systems carbon monoxide detection casings, pump
116 96–97 23–24 36
catalysts
9
ceilings
79
93
centrifugal pumps
35
37
certificates of occupancy certification documentation chemical extinguishing agents
2 18 103
See also dry chemical extinguishing agents; wet chemical extinguishing agents This pa g e has b e e n re fo rma tte d b y Kno ve l to p ro vid e e a sie r navig a tio n.
Index Terms
chemistry of fires
Links
9–12
chlorine
23
churn pressure
38
Class I, II, II standpipes Class A, B, C, D, K combustible materials Class A, B, C, D, K portable fire extinguishers
107
43–45 31
93
115
Class A fires
83
Class A foam concentrate
85
85
Class D fires
105
clean agents
33
107
94
113
comparisons environmental impact
109–110
as extinguishing agents
108–109
safety
110
standards for
107
substances not suitable for
107
system design types of cleaning programs
111–113 108 22
cleanup dry chemicals extinguishing agents wet chemicals
104 31 106
closed bulbs (water mist systems)
92
clouds (Co2)
95
codes and standards codes, defied
1
NFPA standards (See under NFPA) performance-based standards, defied
108
1–2 1
UL standards (See under UL (Underwriters Laboratory)) This pa g e has b e e n re fo rma tte d b y Kno ve l to p ro vid e e a sie r navig a tio n.
103
Index Terms
Links
combined dry pipe and preaction sprinkler systems
50
combined standpipe systems
43
combustibility and combustible materials
10–11
classes of materials
31
detection devices for
29
extinguishing agents and
31
fire-retardant treatments
11–12
handling materials during construction occupancy classifications portable fire extinguishers and combustion cooling flames
detecting dry chemical agents and material combustibility
15 51–52 115 9 32
83
106
109
28 104 10–11
preventing
95
suppressing
32
commissioning
17
commissioning plans
18
19
commissioning specifications
18
19
documentation guidelines process
18–19 19 19–20
re- or retro-commissioning
20
standards
17
team
17–18
testing and
97
19
20
commissioning authorities (CxA)
17
compressibility (water)
61
computer rooms
29
concealed sprinklers
54
18
91
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96
Index Terms
concentration of carbon dioxide
Links
100–101
construction commissioning and fire prevention
17–20 4
fire-safety building design
13–15
occupancy classifications
51–52
permits and plan reviews
2–3
sprinkler documentation
58
structural stability of buildings
5
construction managers
17
construction phase (commissioning)
20
contaminants continuous-line detectors
14–15
9 26
contractors contractor’s sheds
15
general contractors
17
installation contractors
17
control-mode specific-application sprinklers
55–56
control panels (alarm systems)
24–25
control rooms
25
control valves
41–42
controls (pumps)
37
cooking oils, fat, or grease
31
105
106
32
83
97
106
109
115 cooling combustion
correction factor (carbon dioxide) corrosion-resistant sprinklers
100–101 53–54
costs detection systems extinguishing agents fire suppression systems
29 113 31
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Index Terms
Links
costs (Cont.) water mist systems coverage (sprinklers)
93 74
Cx. See commissioning CxA (commissioning authorities)
17
18
cylinders (carbon dioxide)
96
98
D dampers
24
deaths smoke inhalation Triangle Shirtwaist fire
9–10 7–8
deep-seated fires
97
deflectors (sprinklers)
56
deluge sprinkler systems
50
density (water)
61
density/area method (sprinklers)
58
design concentration (clean agents) design fires
103
59
73–77
111 6
design phase (commissioning)
20
design review comments
18
19
design/area method (sprinklers)
58
73–77
6
23
detection systems carbon dioxide systems
96
carbon monoxide
23–24
choosing
28–29
clean agents components of
112 24–25
design questions
25
locating
30
manual and automatic
25
types of
25–28
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Index Terms
Links
diesel generator rooms
29
diesel pump drivers
35
discharge devices (foam) discharge head discharge issues (foam) discharge rates (foam) distance to fire extinguishers
36
86–87 36
37
87–88 84 116
documentation certification commissioning
18 18–19
sprinklers
58
training
18
door fan tests
113
doors automatic
14
closing
24
controlling during fires emergency exits
6 13
exit paths
5
fire-rated
5
locked
7
propping open
5
smoke control and double drivers double shots (carbon dioxide)
24
10
13–14
14
36 101
drainage rates (foam)
84
drains (sprinkler systems)
57
dry chemical extinguishing agents
31
33
116 dry ice
95
dry pendant sprinklers
54
dry pipe sprinkler systems
48–49
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103–105
Index Terms
Links
dry pipe sprinkler systems ( Cont.) alarms
55
design area
79
drainage
57
testing
21
dry pipe valves
80
59
48–49
dry standpipe systems
43
dry upright sprinklers
54
dump-in proportioning
86
Dv0.99
89
E early suppression fast response sprinklers
54
56
ECARO-25 (HFC-125, FE-25)
33
108
110
113 eductors
86
electric pump motors
35
36
electrical equipment
31
96
105
115
63–64
77–78
6
7
24
76
77
elevation, pressure and elevators emergency exits
13
end suction pumps
35
endothermic processes energy (thermodynamics) engineered dry chemical systems
101
9 63 104–105
environmental impacts clean agents extinguishing agents foam
109–110 113 87–88
halon compounds
107
equivalent lengths of pipe
65
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Index Terms
Links
ESFR (early suppression fast response sprinklers)
54
56
evacuating personnel
96
98
evacuation signaling
30
evaporative cooling
109
exits
5
13
exothermic processes
9
11
expansion rate (foam)
84
explosions
27
explosives
29
exposure risks extended coverage sprinklers extinguishing agents
110 53
55–56
6
31–33
alternatives to water
33
clean agents
33
dry chemicals
33
foam
33
inert gases
33
wet chemicals
33
extinguishing fires Extra Hazard Group 1 occupancy
83–88
11–12 52
55
56
58 Extra Hazard Group 2 occupancy
52
58
F FAAP (fire alarm annunciator panels)
24
facility managers
17
FACP (fire alarm control panels)
24
falling fuel fires
83
false alarms
25
29
4
53
54
105
106
fast-response sprinklers (quick-response)
79 fats (cooking fires)
31 115
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Index Terms
FCxA (fire commissioning agents) FE-13 (HFC-23) FE-25 (HFC-125, ECARO-25)
Links
17
18
108
110
33
108
20
110
113 film-forming fluoroprotein (FFFP)
84
85
final commissioning reports
18
19
fire alarm annunciator panels (FAAP)
24
fire alarm control panels (FACP)
24
fire alarm systems. See alarm systems fire commissioning agents (FCxA)
17
18
fire department connections
22
41
15
115–116
fire department notification. See notification systems fire detection systems. See detection systems fire extinguishers fire hydrants. See hydrants fire inspectors
2
fire notification systems. See notification systems fire prevention dangerous conditions
4
detection and notification
6
fire safety personnel
14
safe building design
13–15
suppression systems
6–8
fire protection authorities having jurisdiction
2–3
codes and standards
1–2
fire prevention fire safety personnel organizations passive fire protection safe building design fire protection organizations fire pump rooms
4 14 3–4 5 13–15 3–4 40
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20
Index Terms
Links
fire pumps. See pumps fire-rated barriers fire-retardant (resistant) treatments fire safety personnel fire service mains
5
13–14
11–12 14 3
14
45 fire signatures
9–10
fire sprinklers. See sprinkler systems fire suppression systems
6–8
See also specific types of systems alternatives designing extinguishing agents pre-engineered
33 6–8 31–33 6
fire triangle
31
fire walls
13
fires chemistry and physics
9–12
deep-seated
97
design fires
6
extinguishing
11–12
fire triangle
31
foam suppression
83
material combustibility
10–11
preventing
4
smoke and
9–10
speed of Triangle Shirtwaist fire types of worst-case
28 7–8 29 6
fitting friction losses
65
76
fixed-temperature heat detectors
26
29
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42
Index Terms
FK-5-1-12 (3M Novec 1230, Sapphire)
Links
33
108
110
113 flame detectors
27–28
29
flames, cooling
32
83
106
109
flammable liquids carbon dioxide and
96
classes of combustible materials
31
dry chemical extinguishing
103
fighting fires
32
foam extinguishing
83
NFPA standards
83
occupancy classifications
52
portable fire extinguishers and water mist systems and flash points
115 93 9
flooding carbon dioxide systems clean agents dry chemicals flooring
97
99
111 104–105 13
flow axisymmetric calculating one-dimensional
62 62–63 62
flow rates calculating exiting pipes extinguishing agents
62–63 66 6
flow tables
65
flushing sprinkler systems
59
private fire service mains
42
66–72
This pa g e has b e e n re fo rma tte d b y Kno ve l to p ro vid e e a sie r navig a tio n.
97
Index Terms
Links
flow rates (Cont.) standpipe systems
44
flow switches
24
flow tables
65
flow tests
45
fluorine
66–72
107
108
fluoroprotein foam (FP)
84
85
flush sprinklers
54
flushing private fire service mains
42
sprinkler systems
59
standpipe systems
45
FM Global Approval Guide Approval Standard for Water Mist Systems Property Loss Prevention Data Sheets
4 4 90 4
water mist systems
91
FM-200 (HFC-227ea)
33
108
110
113
109
foam characteristics
84
discharge devices
86–87
environmental impacts
87–88
expansion rates
84
as extinguishing agent
31
guidelines for
87
NFPA standards
83
proportioning storage
85–86 87
testing schedule
116
twin-agent systems
103
types of
33
84–85
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83
Index Terms
Links
foam (Cont.) wet chemicals fog (Co2)
106 95
formulas and hydraulic calculations carbon dioxide extinguishers
97
compressibility
61
density/area method
73–77
elevation changes
77–78
flow in pipes
62–63
halocarbon concentration
112
Hazen-Williams formula
64–65
hydraulically-calculated sprinkler sizing
58
hydraulics overview
61
K factor
77
looped or gridded piping
80–82
NFPA forms
78–79
pressure losses in pipes
63–65
pressure-relief venting pump pressure
99–101
81–82
81
100–101 64
sprinkler coverage
74–78
sprinkler tank pressure
38–39
standpipe pressure
64
total head
36
water exiting pipes
66
water flow tables
65
66–72
FP (fluoroprotein foam)
84
85
sprinkler systems and
48
49
standpipe systems and
43–44
freezing temperatures
water fire suppression systems friction, fires and
32 9
friction losses. See pressure losses This pa g e has b e e n re fo rma tte d b y Kno ve l to p ro vid e e a sie r navig a tio n.
50
Index Terms
Links
fuel additives combustibility in fires
85 10–11 9
removing
11
separating from fires
83
32
G gases carbon dioxide (See carbon dioxide) carbon monoxide
23–24
detection
23
hydrogen
9
inert
11
108
108
110
112
11
92
105
32
inert gas agents nitrogen oxygen (See oxygen) gate valves
41
gauge pressure
63
gauges
21
general contractors
17
global warming grease
22
109 31
105
115 green building certification gridded piping
109 80–82
gunpowder
107
GWP (global warming potential)
109
H HAD (heat-actuated detectors)
96
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106
Index Terms
halocarbon replacements
Links
108
halogenated gases
23
halon compounds
107
109
113
116
hangars (aircraft)
29
83
hangers (sprinkler systems)
57
110
hazard classifications deluge systems NFPA sprinkler systems occupancy classifications
50 6–7 51–52
hazardous extinguishers
97
hazardous work, detectors and
29
Hazen-Williams formula
64–65
81–82
9
32
head. See pressure heat heat-actuated detectors (HAD)
96
heat detectors
24
25–27
29
96 heat extraction heaters at construction sites HFC-23 (FE-13) HFC-125 (ECARO-25, FE-25)
89–90 15 108
110
33
108
110
33
108
109
110
113
113 HFC-227ea (FM-200)
high-expansion foam
84
high-piled storage
48
high-pressure carbon dioxide systems
98
high-pressure water mist systems
92
history of fire codes
55
7–8
horizontal split-case pumps
35
horizontal surface fires
83
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Index Terms
horns
Links
6
hose application (dry chemicals)
24
104
hose houses
42
hose stations
44
hose systems. See standpipe and hose systems HVAC systems
6
hydrants during construction
15
fire service mains for
41
fixed water systems
32
valves
42
hydraulic calculations. See formulas and hydraulic calculations hydraulic pipe schedules
65
hydraulically-calculated sprinkler sizing
58
hydrazine
66–72
107
hydrocarbons hydrogen hydrostatic tests
11
84
9
11
108
45
59
116
109
110
109
110
I IBC (International Building Code)
1
IDC (initiating device circuits)
24
IFC (International Fire Code)
1
IG-55 (ProInert, Argonite)
33 113
IG-100 or -541 (Inergen)
33 113
IMO (International Maritime Organization)
90
91
impellers (pump)
36
40
impingement nozzles
92
impregnation
12
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Index Terms
Inergen (IG-100 or -541)
Links
33
109
110
110
112
113 inert gas agents
108
inert gases
32
infrared detectors
28
inhibitors
29
9
initiating device circuits
24
inlet (suction) head
36
inline pumps
35
inspection reports
18
37
inspections fire extinguishers fire inspectors
116 2
schedules
21
standards
3
installation contractors
17
insurance representatives
18
integrated testing
18
intelligent sensors
24
intermediate-pressure water mist systems
92 1
International Fire Code
1
iodine
20
109
International Building Code
International Maritime Organization
87
20–21
integrated testing agents
Intergovernmental Panel on Climate Change
21
90
91
108
ionization-type smoke detectors IPCC (Intergovernmental Panel on Climate Change)
27
28
109
isolating areas
24
issue logs
18
19
ITA (integrated testing agents)
18
20
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29
Index Terms
Links
J jockey pumps
38
Joule, James Prescott
63
K K factor
66
75
77
kitchen equipment
96
105
115
kitchen grease or fats
31
105
106
51
55
56
58
90
115
L leakage carbon dioxide systems clean agent systems
100 112–113
fire service mains
42
sprinkler systems
59
Life Safety Code (NFPA 101) Light Hazard occupancy
7–8
light-obscuring smoke detectors
27
light-scattering smoke detectors
27
limited combustibility
11
line proportioners
86
linen chutes
58
lithium
107
LOAEL (lowest-observed-adverse-effect level)
110
local application carbon dioxide systems
97
clean agents
111
dry chemical systems
104
wet chemical systems
106
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Index Terms
looped piping
Links
80–82
low-expansion foam
84
low-pressure carbon dioxide systems
98
low-pressure water mist systems
92
lowest-observed-adverse-effect level (LOAEL)
110
M machinery, water mist systems and
91
magnesium
31
96
107
115 main drains
45
59
mains providing during construction standards
14 3
42
45
21
87
105
maintenance fire extinguishers ongoing preventative standards
116 21–22 22 3
manual detection systems
25
manual dry standpipes
43
manual fire alarm boxes
24
manual wet standpipes
43
manufacturer representatives
17
master streams
42
mechanical water flow alarms
54–55
medium-expansion foam
84
metals
31
96
107
115
microbiologically influenced corrosion (MIC)
48
mobile carbon dioxide systems
97
monitor nozzles
42
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Index Terms
monoammonium phosphate motors, pump
Links
103 35
N NAC (notification appliance circuits)
24
30
NFPA (National Fire Protection Association) fire pump studies
35
NFPA Type 1 or 2 foam discharges
87
standards
1
3
NFPA 3: Recommended Practice for Commissioning of Fire Protection and LifeSafety Systems
17
NFPA 4: Standard for Integrated Fire Protection and Life Safety System Testing
17
20–21
NFPA 10: Standard for Portable Fire Extinguishers
115
NFPA 11: Standard for Low-, Medium-, and High-Expansion Foam
83
NFPA 13: Standard for the Installation of Sprinkler Systems
3
6–7
25
47
57–58
73
78–79 NFPA 14: Standard for the Installation of Standpipe and Hose Systems
3
45
NFPA 16: Standard for the Installation of Foam-Water Sprinkler and Foam-Water Spray Systems
83
NFPA 17: Standard for Dry Chemical Extinguishing Systems
103
NFPA 17A: Standard for Wet Chemical Extinguishing Systems
105
NFPA 20: Standard for the Installation of Stationary Pumps for Fire Protection
3
36
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93
Index Terms
Links
NFPA (National Fire Protection Association) standards (Cont.) NFPA 22: Standard for Water Tanks for Private Fire Protection
32
NFPA 24: Standard for the Installation of Private Fire Service Mains and Their Appurtenances
3
42
45
3
21
87
NFPA 25: Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems
NFPA 30: Flammable and Combustible Liquids Code
83
NFPA 33: Standard for Spray Application Using Flammable or Combustible Materials
NFPA 72: National Fire Alarm and Signaling Code NFPA 92: Standard for Smoke Control Systems
103 6
25
10
NFPA 96: Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations
NFPA 101: Life Safety Code NFPA 220: Standard on Types of Building Construction
105 7–8 11
13
NFPA 403: Standard for Aircraft Rescue and Fire-Fighting Services at Airports
83
NFPA 409: Standard on Aircraft Hangars
83
NFPA 720: Standard for the Installation of Carbon Monoxide (CO) Detection and Warning Equipment
23
NFPA 750: Standard on Water Mist Fire Protection Systems
89
90
93 NFPA 1150: Standard on Foam Chemicals for Fires in Class A Fuels
83
NFPA 2001: Standard on Clean Agent Fire Extinguishing Systems
107
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91–92
Index Terms
nitrogen
Links
11
NOAEL (no-observed-adverse-effect level)
92
105
110
non-aspirated foam discharge
86
non-combustible materials
11
notification appliance circuits
24
30
notification systems
6
23
components
24
notification appliance circuits
24
30
33
108
110
55
58
Novec 1230 (FK-5-1-12, Sapphire)
113 nozzle sprinklers
54
nozzles monitor nozzles (master streams)
42
placement
6
standards
4
water mist systems
92
O obstructions (sprinklers)
56
occupancy classification fire suppression systems
6
permits and plan reviews
2
sprinkler design and types of water mist systems and
48 51–52 91
occupancy phase (commissioning)
20
occupants, fire safety and
14
Occupational Safety and Health Administration
98
ODP (ozone depletion potential)
109
offices
29
oil pressure alarms
36
on/off sprinklers
54
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Index Terms
Links
open areas
29
open nozzles (water mist systems)
92
open sprinklers
53
OPR (owner’s project requirements)
17
18
19
Ordinary Hazard Group 1 occupancies
51
55
56
58 Ordinary Hazard Group 2 occupancies
51–52
orifices (sprinklers)
53
ornamental sprinklers
54
OSHA (Occupational Safety and Health Administration)
98
ovens
96
58
105
owners in commissioning team
17
in design drawings
58
fire suppression systems and
14
owner’s information certificate
48
owner’s project requirements
17
permitting process
18
19
19
2–3
owner’s information certificate
48
owner’s project requirements
17
18
oxidizing agents
11
96
oxygen biological oxygen demand
88
carbon dioxide systems and
98
combustion and
9
in fire triangle
9
32
11
32
89–90
95
109
110
removing
oxygenated fuel additives ozone layer
85 107
109
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Index Terms
Links
P P (protein film)
84
paddle-type water detectors
28
85
passive fire protection
5
13–14
paths of travel
5
13
pendant sprinklers
53
55–56
penetrations
13
percentages (foam mixtures)
85–86
performance-based codes
1–2
permits
2–3
peroxides
107
personnel in commissioning
17
fire safety
14
health effects of agents on
110
113
photoelectric smoke detectors
27
29
physics of fires
9–12
pipe schedules
57
pipes carbon dioxide systems clean agent systems
96
99–101
112
hydraulics and (See formulas and hydraulic calculations) looped or gridded systems
80–82
pressure losses (See pressure losses) roughness
64–65
sprinkler systems
54
water flow tables
65
pitch (drains)
57
PIV (post-indicator valve)
41
plan reviewers
66–72
2
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Index Terms
planning phase (commissioning)
Links
19–20
plastics, storage
48
pneumatic tests
59
polar liquids
84
portable carbon dioxide systems
97
portable dry chemical systems
85
104
portable fire extinguishers
15
post-indicator valves (PIVs)
41
potassium
96
potassium acetate
105
potassium bicarbonate
103
potassium carbonate
105
potassium citrate
105
115–116
107
pounds per square inch
63
power supplies
23
24
6
105
pre-engineered suppression systems pre-mix proportioning preaction sprinkler systems
86 49–50
57
79 pressure. See also pressure losses absolute
63
air
63
atmospheric
63
booster pumps
37
carbon dioxide systems
99
churn
38
clean agent systems discharge head elevation and extinguishing agents
100–101
112–113 36 63–64 6
fire pumps
35
36
foam
86
87
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59
Index Terms
Links
pressure (Cont.) gauge
63
Hazen-Williams formula
64–65
hydropneumatic tanks
38–39
inspections
21
K factor
66
looped or gridded piping
80–82
maintaining in systems
38–39
private fire service mains
42
sprinkler systems
55
standpipe systems
44
suction head
36
total head
36
water mist systems
91
pressure-activated alarms
55
pressure impregnation
12
pressure jet nozzles
92
59
74–78
92
pressure losses calculating carbon dioxide systems dry chemical systems and
63–65 99 105
fittings and valves
65
friction losses in flow
63
Hazen-Williams formula
64–65
looped or gridded piping
80–82
sprinkler systems
74–78
pressure-regulating devices
45
pressure-switch water detectors
28
pressure transducers
38
pressurized fires
83
preventative maintenance
22
priming
21
59
36
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112–113
Index Terms
private fire service mains
Links
3
14
42
109
110
45 private water supplies
41
ProInert (IG-55)
33 113
propellants in water mist systems proportioning foam
92 85–86
protein foam (P)
84
psi (pounds per square inch)
63
puff tests
98
pull stations
24
pump rooms
40
pumps
85
35–36
booster
37
capacity
36
components
36–37
jockey
38
pressure example
64
pump curves
39–40
pump rooms
40
reservoirs and
32
spare
37
standards water mist systems and Purple K
39–40
3
36
93
53
54
93 103
Q QR (quick-response sprinklers)
4 79
QREC (quick-response extended coverage sprinklers)
54
QRES (quick-response early suppression sprinklers)
54
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Index Terms
Links
R rack storage areas
29
48
radiant energy detectors
25
27–28
radiant heat radiative forcing
89–90 109
rate compensation heat detectors
26
29
rate-of-rise heat detectors
26
27
ratings (fire-rated barriers)
5
ratios (foam mixtures)
85–86
RDP (registered design professionals)
17
re-commissioning
20
recessed sprinklers
54
reflashing
97
registered design professionals (RDP)
17
regulations (extinguishing agents)
18
113
remodeling buildings
15
remote annunicators
24
remote areas (hydraulics)
74
repairs
22
replacing parts
22
reservoirs
32
residential sprinklers
54
residue
97
resolution logs
18
restraints (sprinkler systems)
57
retro-commissioning
20
rock sites
15
rocket propellant
29
roof holes
31
room design method (sprinklers)
58
room integrity tests
18
20
56
113
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29
Index Terms
roughness of pipes rubber, storage
Links
64–65 48
S safety clean agents
110
extinguishing agents
113
safety of life at sea (SOLAS)
89
saponification Sapphire (FK-5-1-12, 3M Novec 1230)
104
106
33
108
113 scales (weight)
98
sectional control valves
41–42
self-restoring detectors
26
semiautomatic dry standpipes
43
sensors
24
shelters, construction
15
shutoff pressure (fire pumps)
35
sidewall sprinklers
53
signaling line circuits
24
single-fluid water mist systems
45
55–56
91–92
sizing carbon dioxide systems pumps
99–101 37
sprinkler systems SLC (signaling line circuits) smoke
57–58 24 9–10
smoke alarms
4
smoke barriers
6
smoke control
10
smoke detectors choosing
29
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110
Index Terms
Links
smoke detectors (Cont.) designing systems
24
locating
30
standards types of smoke evacuation systems
25
4 27 24
smoke inhalation
9–10
smoke pencil tests
113
smoke-stop doors
14
smothering fires
31
83
97
107
115
106 soda acid
116
sodium
96
sodium bicarbonate
103
SOLAS (safety of life at sea)
89
spacing sprinklers
56
spare pumps
37
sparks
9
special design areas (sprinklers)
58
speed of fires
28
48
spot detectors
26
30
sprinkler heads
52–54
sprinkler systems alarms
54–55
area modifications
79–80
basis of design
48
compared to water mist systems
94
components and materials
52–55
coverage
74
design and construction documents
58
designing drains
47–50
57–58
57 This pa g e has b e e n re fo rma tte d b y Kno ve l to p ro vid e e a sie r navig a tio n.
73–77
Index Terms
Links
sprinkler systems ( Cont.) fixed water systems
32
hangers and restraints
57
history
47
hose stations and
44
hydraulics (See formulas and hydraulic calculations) hydropneumatic tanks
38–39
installation and location
55–57
looped or gridded piping
80–82
maritime NFPA hazard classes occupancy classifications pipe materials pressure and during remodels sizing
89 6–7 51–52 54 38–39 15 57–58
standards NFPA 13
3
6–7
25
47
57–58
73
78–79 UL 199
4
UL 1626
4
UL 1767
4
temporary
14
testing
22
59
48–50
53–54
types of water flow detection stabilizers
25 9
stack effects
10
stairwells designing
13
pressurization
10
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Index Terms
Links
standards. See codes and standards standpipe and hose systems analyzing requirements for
42–45 42–43
carbon dioxide systems
97
classes of
43
fixed water systems
32
flow rates
44
hose connections
44–45
looped or gridded piping
80–82
materials for
45
pressure example
64
providing during construction
14
standards testing types of
3
45
45 43–44
start points (pumps)
38
steam
83
steam turbines
36
stop points (pumps)
38
90
storage clean agents
112
dry chemical systems
105
extinguishing agents
113
wet chemical systems
106
storage spaces carbon dioxide systems occupancy classifications sprinklered
101 51–52 48
storage tanks
32
87
strobe lights
6
24
structural stability of buildings
5
submittal review comments
18
19
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Index Terms
Links
suction head
36
suction lift
35
surface fires system manuals
37
103 18
19
tall buildings
10
24
tamper switches
28
tanks
32
T
38–39
87
96 temper switches
55
temperature cooling combustion
32
foam applications
87
freezing (See freezing temperatures) hydraulic calculations
61
sprinkler heads and
52
sprinkler ratings
53
test data reports
18
19
testing carbon dioxide systems clean agent systems
98 113
in commissioning
17
fire extinguishers
116
foam systems
87
for inspections
21–22
integrated testing
20–21
private fire service mains
42
sprinkler systems
59
standards
19
3
17
87 water mist systems wet chemical systems
91 105
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20–21
Index Terms
Links
textile mills
47
thermal sensitivity
53
thermodynamics
63
third-party testing
18
“three times rule”
56
timers (pump)
36
titanium
31
96
97
99
total flooding carbon dioxide systems clean agents dry chemicals
111 104–105
total head
36
training documentation
18
transporting extinguishing agents trash chutes
113 58
travel distance (fire extinguishers)
116
Triangle Shirtwaist fire
7–8
trip tests
59
triple point pressure (CO2)
95
turbines
91
twin-agent systems
103
twin-fluid water mist systems
92
Types 1, 2 or 3 foam dischargers
87
94
U UL (Underwriters Laboratory)
3–4
fire pump listings
35
foam dischargers (UL Type 1, 2, 3)
87
ratings (fire extinguishers)
115
standards UL 199: Standard for Automatic Sprinklers for Fire Protection Service
4
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115
Index Terms
Links
UL (Underwriters Laboratory) standards (Cont.) UL 217: Standard for Smoke Alarms
4
UL 268: Smoke Detectors for Fire Alarm Systems
4
UL 300: Fire Testing of Fire Extinguishing Systems for Protection of Commercial Cooking Equipment
105
UL 1254: Standard for Pre-Engineered Dry Chemical Extinguishing System Units
103
UL 1626: Standard for Residential Sprinklers for Fire Protection Service
4
UL 1767: Standard for Early-Suppression Fast Response Sprinklers
4
UL 2127: Standard for Inert Gas Clean Agent Extinguishing System Units
107
UL 2166: Standard for Halocarbon Clean Agent Extinguishing System Units
107
UL 2167: Standard for Water Mist Nozzles for Fire Protection Service
90
UL 2351: Standard for Spray Nozzles for Fire Protection Service
4
ultraviolet detectors
29
ultraviolet light
28
Underwriters Laboratory. See UL (Underwriters Laboratory) unlocking doors
24
upright sprinklers
53
uranium
107
urea-potassium bicarbonate
103
55–56
V valuables
48
49
96 This pa g e has b e e n re fo rma tte d b y Kno ve l to p ro vid e e a sie r navig a tio n.
93
Index Terms
Links
valves friction losses
65
inspections
21
private fire service mains
41
sprinkler systems
55
59
testing
22
59
vane-type water flow alarm
54
vapors
83
velocity
36
62–63
24
29
ventilation equipment detectors and dry chemicals and HVAC systems water mist systems and venting carbon dioxide systems vertical turbine pumps
104 6 90 100–101 35
viscosity
61–62
visibility
98
voice instructions
93
6
volume (carbon dioxide)
99
volume (water)
61
W walls, fire-rated
5
warnings (carbon dioxide)
98
warranties
19
58
water density
61
as extinguishing agent
11
31
hydraulic calculations (See formulas and hydraulic calculations) hydrocarbons and
11
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32
Index Terms
Links
water (Cont.) temporary sources of viscosity wet water
14 61–62 11
water-driven foam proportioners
86
water flow alarms
22
30
54–55
water flow detectors
24
25
28
water flow tables
65
66–72
water heaters
23
water mist systems
89
compared to other systems
94
designing
92–94
extinguishing fires
89–90
history
89
pressure
92
standards
89
technical issues
94
types of water motor gongs
90–91
91–92 54–55
water-reactive liquids
83
water-reactive metals
105
water spray systems
94
water tanks
32
weight carbon dioxide cylinders
98
water
61
welding
64
14–15
wet chemical extinguishing agents
33
105–106
wet pipe sprinkler systems
48
49
57
79
wet standpipe systems
43
wet water
11 This pa g e has b e e n re fo rma tte d b y Kno ve l to p ro vid e e a sie r navig a tio n.
50
