Medical Gas Systems Presented By: Ed Tinsley, PE, CEM, CHFM, HFDP, LEED TM AP TME, Inc.
Agenda • Int Introd roduct uction ion to to Medica Medicall Gas Syste Systems ms • App Applic licabl able e Codes Codes and and Regula Regulatio tions ns • Des Design igning ing Med Medica icall Gas Sys System tems s • Ins Instal tallin ling g Medica Medicall Gas Sys System tems s • Mai Mainta ntaini ining ng Medic Medical al Gas Gas System Systems s • Su Sum mma mary ry • Fu Furt rthe herr St Stud udy y 2
Agenda • Int Introd roduct uction ion to to Medica Medicall Gas Syste Systems ms • App Applic licabl able e Codes Codes and and Regula Regulatio tions ns • Des Design igning ing Med Medica icall Gas Sys System tems s • Ins Instal tallin ling g Medica Medicall Gas Sys System tems s • Mai Mainta ntaini ining ng Medic Medical al Gas Gas System Systems s • Su Sum mma mary ry • Fu Furt rthe herr St Stud udy y 2
Medical Gas System “An assembly of equipment and piping for the distribution of nonflammable medical gasses such as oxygen, nitrous oxide, compressed air, carbon dioxide, and nitrogen.” * NFPA 99C, Chapter 3, Definitions 3
Common Medical Gas Systems • • • • • • • •
Oxygen Oxyg en (O2) Medic Me dical al Ai Airr (M (MA) A) Medic Me dical al Va Vacuu cuum m (MV (MV)) Nitrou Nit rous s Ox Oxide ide (N2O) Nitr Ni trog ogen en (N2) Instrume Inst rumental ntal Air (IA (IA)) Carbon Car bon Dio Dioxi xide de (CO2) Wast Wa ste e Anest Anesthes hesia ia Gas Gas Disposal (WAGD or EVAC) 4
Oxygen (O2) • An element that at atmospheric temperatures and pressures exists as a colorless, odorless, tasteless gas. • Primarily used for respiratory therapy and anesthesia. • Has the ability to support life and to support combustion. Although oxygen is non-flammable, materials that burn in air will burn much more vigorously and create higher temperatures in oxygen or oxygen-enriched atmospheres.
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Oxygen (O2) • Comprises approximately 21% of the earth’s atmosphere. • Liquid oxygen exists at cryogenic temperature, -300ºF at atmospheric pressure. When warmed to room temperature, it will expand to fill a volume 860 times its liquid volume. • 50 to 60 psig 6
Nitrous Oxide (N2O) • An oxide of Nitrogen • Exists as a gas at atmospheric conditions. • Possesses a “sweetish” smell. • Capable of producing the first and second stages of anesthesia when inhaled. • Oxygen is released under conditions of combustion, creating an oxygenenriched atmosphere. • Primarily used as an anesthetic. • 50 to 60 psig 7
Medical Air (MA) • Medical air is supplied from cylinders, bulk containers, medical air compressors and treatment equipment, or has been reconstituted from oxygen and nitrogen. • Exclusively used for human respiration or calibration of devices for respiratory application. • Primarily used for respiratory therapy. • Hydrocarbon carryover from the compressor poses a threat to the end user and increases the risk of fire especially when mixed with oxygen.
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Medical Air (MA) • The quality of the local ambient air should be considered prior to its selection for compressors and treatment equipment. • A medical air compressor is designed to exclude oil from the airstream and compression chamber and that does not under normal operating conditions, or any single fault, add any toxic or flammable contaminants to the compressed air. • 50 to 60 psig
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Medical Vacuum (MV) • An assembly of central
vacuum producing equipment and a network of piping for patient suction in medical, medical-surgical, and waste anesthetic gas disposal (WAGD) applications. • Primarily used for patient treatment in surgery, recovery, and ICU to remove fluids and aid in drainage. • 15 to 25” Hg 10
Nitrogen (N2) • Exists as a gas at atmospheric temperatures and pressures. • Clear, colorless, and tasteless gas. • Comprises approximately 78% of the earth’s atmosphere. • Used for pipe joining and pressure testing purposes. • Used to power instruments. • 160 psig 11
Instrument Air (IA)
• Substitute for nitrogen for powering instruments unrelated to human respiration (surgical tools, ceiling arms, etc.). • Medical air and instrument air are distinct systems for mutually exclusive applications. • 200 psig 12
Carbon Dioxide (CO2)
• Occasionally used for surgical procedures and laboratory applications.
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Waste Anesthesia Gas Disposal (WAGD) • Also referred to as “scavenging” or “evacuation”. • Used to capture and carry away gases vented from the patient breathing circuit during the normal operation of gas anesthesia or analgesia equipment. • Can be connected to the medicalsurgical vacuum system under certain conditions but discouraged. • Low vacuum (0.014” Hg at patient) 14
Applicable Codes and Regulations
• AIA Guidelines for the Design and Construction of Hospital and Health Care Facilities • NFPA 99, Health Care Facilities • Other Codes and Regulations • Other Guidelines • State and Local Codes and Regulations 15
AIA Guidelines • American Institute of Architects Academy of Architecture for Health, Facilities Guideline Institute and U. S. Department of Health and Human Services • 2006 Edition • Establishes minimum standards for constructing and equipping health care facility projects • Basis for many state codes and regulations • Addresses all types of health care facilities including general hospitals, nursing facilities, outpatient facilities, rehabilitation facilities, psychiatric hospitals, mobile units, hospice, assisted living, etc. 16
AIA Guidelines • 7.31.E5 The installation, testing, and certification of nonflammable medical gas and air systems shall comply with the NFPA 99. (See table 7.5 for rooms requiring station outlets.) • 7.31.E6 Clinical vacuum system installations shall be in accordance with NFPA 99. 17
Excerpt from Table 7.5 Station Outlets for Oxygen, Vacuum (Suction), and Medical Air Systems in Hospitals1 Location
Oxygen
Vacuum
Medical Air
7.2A
Patient rooms (medical and surgical)
1/bed
1/bed
----
7.2.B10
Examination/treatment (medical, surgical, and postpartum care)
1/room
1/room
----
7.2C/7.2.D
Isolation—infectious and protective (medical and surgical)
1/bed
1/bed
----
7.3.A
Critical care (general)
3/bed
3/bed
1/bed
7.3.A14
Isolation (critical)
3/bed
3/bed
1/bed
7.3.B
Coronary critical care
3/bed
2/bed
1/bed
7.3.D
Pediatric critical care
3/bed
3/bed
1/bed
7.3.E
Newborn intensive care
3/bassinet
3/bassinet
3/bassinet
Section
1 For any area or room not described above, the facility clinical staff shall determine outlet
requirements after consultation with the authority having jurisdiction. 18
NFPA 99, Health Care Facilities
• Chapter 5 addresses gas and vacuum systems. • 2002 Edition or 2005 Edition • Chapters 13, 14, 17, 18, 19, 20, and 21 contain facility specific requirements.
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Chapter 5 – Gas and Vacuum Systems • Section 5.1 establishes requirements for Level 1 systems. • Section 5.2 establishes requirements for Level 2 systems. • Section 5.3 establishes requirements for Level 3 systems. • Each section addresses sources, valves, station outlets/inlets, manufactured assemblies, pressure and vacuum indicators, warning systems, distribution, labeling and identification, performance criteria and testing, and operation and management. 20
System Categories by Level of Risk* • Level 1: “System serving patients where an interruption of the piped gas or vacuum system would place patients in imminent danger of morbidity or mortality.” • Level 2: “Interruption of system would place patient at manageable risk of morbidity or mortality.” • Level 3: Interruption of system would terminate procedure but would not put patient at risk.” * The entire system shall comply to Level 1 if any part of the system is required to be Level 1
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Potential Hazards • Fire hazard – O2 and N2O support and enhance combustion • Potential service interruption • Build-up of potentially hazardous concentrations • Suffocation due to O2 displacement (N2, CO2, and N2O) • Contamination • Mix-up of gases 22
FDA Public Health Advisory “This guidance is intended to alert hospitals, nursing homes, and other health care facilities to the hazards of medical gas mix-ups. The Food and Drug Administration (FDA) has received reports during the past 4 years from hospitals and nursing hospitals involving 7 deaths and 15 injuries to patients who were thought to be receiving medical grade oxygen, but were receiving a different gas (e.g., nitrogen) that had been mistakenly connected to the oxygen supply system. This guidance makes recommendations that will help hospitals, nursing homes, and other health care facilities avoid the tragedies that result from medical gas mix-ups.” 23
Other Codes & Regulations
• ANSI – American National Standards Institute • ASME – American Society of Mechanical Engineers • ASSE – American Society of Sanitary Engineering • ASTM – American Society for Testing and Materials • AWS – American Welding Society • CGA – Compressed Gas Association • Pamphlets: G-4 Oxygen Systems, G-4.1 Cleaning Equipment for Oxygen Service, 02-DIR Directory of Cleaning Agents for Oxygen Service, etc. 24
Designing Medical Gas Systems
• Estimating flow requirements • Selecting equipment • Pipe sizing • Zone valves and alarms • Electrical service • Equipment space requirements
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Estimating Flow Requirements • Number of outlets • Flow rate per outlet (depends on the specific gas and outlet type) • Diversity factor (depends on the number and type of outlets)
Medical Gas Flow Reqmts. Project: Project #: O ut le t L oc at io n
Thoracic OR Major OR Minor OR Special Procedures Delivery Rooms Recovery Beds Outpatient Revcovery Beds Intensive Care Beds Emergency Beds Pat. Surgical Beds Pat. Medical Beds Nurseries Beds LDRP Beds Labor Beds Treatment Rooms Exam Rooms Autopsy Respiratory Therapy Radiology Rooms Nuclear Medicine Cardiac Stress Anesthesia Workrm. Total Average Load (cfm)
# o f O R' s V ac uu m # o f M ed . A ir # o f O xy ge n # o f N it ro us # o f N it ro ge n or beds outlets outlets outlets Oxide outlets (cfm) (cfm) (cfm) (cfm) (cfm) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.0 0 0 0 0 0 0.0 0 0 0 0 0 0.0 0 0 0 0 0 0.0 0 0 0 0 0 0.0 0 0 0 0 0 0 0
0 0
0.0 0
0 0
0 0
0 0
0 0
0
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0
Typical Outlet Flow Requirements • O2 – 1 SCFM (6.5 SCFM for adult ventilator and 1 SCFM for infant ventilator) • N20 – 1 SCFM • N2 – 1.5 SCFM per operating room • MA – 1 SCFM • MV – Varies • WAGD – 1 SCFM (Some anesthesia systems use modified interface valves with larger inflows up to 2 SCFM) 27
Typical Diversity Factors for O2 & N2O Quantity of Outlets
Diversity (%)
1–3
100
4 – 12
75
13 – 20
50
21 – 40
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Diversity charts yield erratic flow calculations. Many designers prefer to use diversity graphs. 28
SCFM vs. ACFM • Loads are calculated in SCFM. Compressors and vacuum pumps, however, are typically rated in ACFM. • SCFM = Standard cubic feet per minute (14.696 psia and 60ºF*) • ACFM = Actual cubic feet per minute • ACFM = Pst x (T1 + 460) x SCFM (P1 – Pv) (Tstd + 460) * Sometimes other conditions are used such as 70ºF, 68ºF, and 36% RH 29
Selecting Equipment • Altitude is important! – 100 SCFM = 107 ACFM in Los Angeles – 100 SCFM = 130 ACFM in Denver • Consider worst case ambient conditions. ACFM requirements are at their highest on hot and humid days. • ACFM approaches infinity at higher vacuums – 10 SCFM = 17 ACFM @ 12” Hg – 10 SCFM = 50 ACFM @ 24” Hg – 10 SCFM = 153 ACFM @ 28” Hg 30
Bulk Oxygen Systems • 3.3.1.9 Bulk system. An assembly of equipment, such as storage containers, pressure regulators, pressure relief devices, vaporizers, manifolds, and interconnecting piping, that terminates at the point where the system gas at service pressure first enters the facility supply line. Bulk systems contain more than 20,000 ft3 of oxygen or 3,200 lb of nitrous oxide including unconnected reserves on the site. 31
Bulk Oxygen Systems • Typically involves a cryogenic liquid • Subject to NFPA 50, Standard for Bulk Oxygen Systems and NFPA 99 (2005 Edition) • Reserve Supply (2nd cryogenic vessel with economizer or cylinder header) • Emergency oxygen supply connection at each building or in-house reserve with minimum 1 day’s supply 32
Emergency Oxygen Supply Connection Inlet must be located on the outside of the building. Inlet must be accessible at all time and in all weather conditions.
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Medical Air Compressors • Sufficient number and capacity of compressors to serve the calculated peak demand with the largest unit out of service (N + 1 redundancy). • No oil in compressor or separation of crankcase and compressor with 2 seals and atmospheric vent. • Receiver (sufficient size to avoid compressor short cycling)
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Medical Air Compressors • 2 Dryers (dewpoint below 32 deg. F at any level of demand) • Filters (98% efficient at 1 micron) • Dewpoint and CO monitors • 55 - 60 psig • Intake requirements – – – –
Above roof Not close to any contaminants Minimum of 20’ above the ground Can connect to OR supply air after HEPA filter if no belts or motors in airstream
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Medical-Surgical Vacuum Pumps • Sufficient number and capacity of pumps (N+1 redundancy) • Vacuum receiver • 18 to 22” Hg • Connection of WAGD to medicalsurgical vacuum system (MSVS) is accepted under certain conditions but not desirable. • Exhaust restrictions – Atleast 10’ away from any building opening – Different level from air intakes
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Connecting WAGD to MSVS • Most common implementation of WAGD in USA is a direct connection to MSVS. • Frequent Assumptions – Cheap (no impact on pump or pipe sizing) – O2 is sufficiently diluted
• Many MSVS utilize an oil-lubricated vacuum pump. • Potential Hazards – Fires in vacuum pumps – Pumps run excessively 37
Connecting WAGD to MSVS • Suggestions – Use a separate low vacuum system for WAGD if possible. – If a combined WAGD – MSVS system is unavoidable, consider WAGD inflows (2.0 SCFM per location) when sizing the pumps and avoid the use of an oil lubricated pump.
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Manifolds and Cylinders • 2 equal headers (any number in 2005 Edition) • Minimum of 2 cylinders per header (any number in 2005 Edition) • Not less than an average day’s supply per header • Automatic changeover to reserve header • Consider vendor proximity when sizing the manifold (more cylinders is better).
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Space Requirements • Cylinder and Manifold Rooms – Dedicated room – Close to loading dock – Ventilated – Heated by indirect means (steam or heating water) – 1 hour fire resistance rating – Electrical devices located at or above 5’ AFF – All relief valves vented to outside – 20 deg. F minimum temperature for N2O and CO2 – Each cylinder must be individually secured (2002 edition)
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Space Requirements • Bulk Systems – NFPA 50 & 99 – Outside – Secure – Illuminated – Accessible • Vacuum Pumps and Medical Air Compressors – Can be located in same room as chillers, air handlers, etc. – Ventilated to prevent accumulation of heat
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NFPA 50
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Pipe Sizing
• Flow Rate (considering diversity) • Allowable friction loss • Equivalent length of pipe • Minimum pipe sizes
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Pipe Sizing Example • 45 SCFM of Medical Air • Longest run is 333 feet • Equivalent length = 333 feet x 150% = 500 feet • Allowable pressure drop* = 5 psi • Pressure drop = 5 x 100 = 1.0 psi 100 feet 500 *Allowable pressure drop is approximately 10% of the source pressure. Approximately 5 psig for O 2, CO2, MA, and N2O, 15 – 20 psig for IA and N2, and 3” Hg for vacuum. 44
Pipe Sizing Example Pressure Loss, PSI per 100 feet in 50 PSI compressed air piping SCFM
Nominal Pipe Size, inches ½
¾
1
1-1¼
1-1½
5
0.30
0.03
0.01
10
1.15
0.18
0.05
0.01
15
0.40
0.11
0.03
20
0.69
0.20
0.05
0.02
25
1.14
0.31
0.07
0.03
30
0.44
0.10
0.05
35
0.61
0.14
0.06
40
0.80
0.18
0.08
45
1.00
0.23
0.10
50
0.29
0.13
60
0.42
0.18
Minimum pipe size is 1”. Suggest 1 ¼’ or 1 ½” to provide capacity for future growth.
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Minimum Pipe Sizes • Mains and branches in medical gas piping systems – ½’” • Mains and branches in medical-surgical vacuum systems – ¾” • Drops to individual outlets/inlets – ½” • Runouts to alarm panels and connecting tubing for gauges and alarm devices – ¼” 46
Valves • Zone Valves – Must be a wall between the zone valve and the outlets served. – All outlets must be served through a zone valve. – A zone valve cannot serve outlets on more than one story.
• Future Valves – – – –
Optional Must be locked closed Must be located in a restricted area Must be properly identified
• Service Valves – Must be located behind a locked access door or locked open above a ceiling or in a secure area – Minimum of 1 per floor per riser
• Riser Valves – Required at each riser
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Valves and Alarms
Critical care areas include ICU, CCU, PACU, Cath Labs, Emergency, and Delivery. 48
Electrical Service • Medical air compressor and medical vacuum pumps must be served by the equipment branch of the essential power system for a delayed automatic connection. • Connection to critical branch is permitted. (Recommended when generator paralleling systems with load shed circuits are used.) 49
Electrical Service • Medical gas alarms must be connected to the life safety branch of the essential power system. • Manifolds must be connected to the essential power system. • Cylinder room ventilation equipment must be connected to the essential power system.
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Constructing Medical Gas Systems
• Coordination of Work • Labeling • Installer Qualifications • Brazing, Soldering, and Purging • Materials • Acceptance Testing
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Coordination of Work • Communication and Coordination are essential! • Establish who has authority to shut off medical gas or vacuum valves (facility personnel either perform shut down or witness). • Recognize the different systems. • In renovations, multiple shutdowns and verifications/certifications may be required.
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Labeling Medical Gas Systems
• NFPA 99C Table 5.1.11
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Labeling Medical Gas Systems
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Installer Qualifications • Installers of medical gas and vacuum systems shall meet the requirements of ANSI/ASSE Standard 6010 – “Professional Qualifications Standard for Medical Gas and Vacuum System Installers.” • “Prior to any installation work, the installer of medical gas and piping shall provide and maintain documentation on the job site for the qualification of brazing procedures and individual brazers . . . .” * NFPA 99, Chapter 5
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Brazing and Soldering
• Brazing required for all Level 1 & 2 systems – Use of flux not allowed except when brazing dissimilar metals
• Soldering allowed only for Level 3 systems – Lead based solders not allowed
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Brazing
Brazed joints appear as dark, burnt connections.
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Soldering
Soldered joints appear as bright silver connections.
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Purging
• Continuous, oil-free, dry nitrogen purge required during all work on medical gas systems • Required to eliminate oxidation • Less than1% oxygen prior to brazing (2005 edition) 59
Purging
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Materials • Tubes, valves, fittings, station outlets, and other piping components in medical gas systems shall have been cleaned for oxygen service by the manufacturer prior to installation. • Each length of tube shall be delivered plugged or capped by the manufacturer and kept sealed until prepared for installation. • Pressure gas tubes shall be hard-drawn seamless copper ASTM B 819 medical gas tube. • Vacuum tubes shall be hard-drawn seamless copper. The use of “roll grooved” and gasketed joining methods is permitted for vacuum only (2002). Plastic pipe is permitted for Level III vacuum only.
Materials Medical gas branches shall take off at an angle of 45 degrees or more above the pipe.
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Materials
63
Materials
Secure medical gas fitting storage
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Materials
Separate, protected, medical gas pipe storage
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Materials
Pipe caps in place on medical gas piping until connection
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Acceptance Testing • NFPA 99C, Chapter 5, requires separate installer and third party testing. – Installer performs initial, non-certified tests – Third-party performs verification and testing • System Verifier - Individual who actually conducts required tests; pressure/flow readings, purity, etc. • Inspector - Individual verifies physical aspects of installation; connections, labeling, materials, etc.; reviews verifier tests reports and installer certifications. 67
Installer Performed Tests • Initial blow-down using oil-free, dry N 2 – After installation of piping – Before installation of components (alarm devices, pressure indicators, relief valves, etc.) • Initial pressure test – 1.5 x working pressure for pressure gases – 60 psig for vacuum – Each joint must be examined • Cross-connection test – Systems tested one at a time with oil-free, dry N 2 at 50 psig – Proper labeling of inlets/outlets
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Installer Performed Tests • Piping purge test – High volume flow of test gas – No discoloration of white cloth – Start at most remote outlet from zone valve • Standing pressure test – 24 hours – 20% above normal system pressures 69
Third Party Testing
• NFPA Chapter 5, System Verification (performed after acceptance of installer tests) – “… by party other than the installer and meeting requirements of ANSI/ASSE Standard 6030”
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System Verification • Test gas shall be oil-free, dry N2 (small projects affecting a limited number of areas may use the source gas). • Standing Pressure Test (10 minutes) • Cross-Connection Test – Individual pressurization – Pressure differential • Valve Test • Alarm Test • Piping Purge Test 71
System Verification • Pi Pipin ping g Purg Purge e Te Test st • Pip Piping ing Part Particul iculate ate Tes Testt • Fi Final nal Ti Tie-I e-In n Tes Testt • Ope Operat rational ional Pres Pressure sure Tes Testt • Med Medical ical Gas Conc Concentr entratio ation n Test Test • Me Medic dical al Air Air Puri Purity ty Tes Testt • La Labe beli ling ng • Sou Source rce Equi Equipmen pmentt Verif Verificat ication ion Note: Be sure to specify Note: specify the appropriate appropriate edition edition of NFPA 99 to the Third Party!
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Maintaining Medical Gas Systems • Ad Admi minis nistr trat ation ion – Purchase specifications for cylinders and regulators – Training • Special Special precau precaution tions s for cyli cylinder nders s and manifolds – No contact with oil or grease – Protected from contamination – Protected from damage 73
Maintaining Medical Gas Systems • Wa Warni rning ng sig signs ns • Preve Preventiv ntive e mainte maintenan nance ce • Per Period iodic ic testin testing g of alarms alarms • Annua Annuall testin testing g of CO CO monitor • Docu Documen mentati tation on – Record drawings – Test results 74
Summary • Proce Proceed ed wit with h caut caution ion.. Me Medic dical al gas systems present many hazards. • Know Know the the codes. codes. Medi Medical cal gas gas systems are tightly regulated. – AIA Guidelines – NFPA 99 • Th There ere are are 3 types types of syst systems ems.. – Level 1 (Imminent Danger) – Level 2 (Manageable Risk) – Level 3 (Little or No Risk) 75
Summary • Flow rates depend on quantity of outlets, type of outlets, and diversity of use. • Medical air compressors and vacuum pumps capacities are based on ACFM not SCFM. • Refer to NFPA 50 for work related to bulk O2 systems. • Medical air compressors and medical vacuum pumps require N + 1 redundancy for all components except the receiver. • Although common, connecting WAGD to MSVS is discouraged.
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Summary • More cylinders are better. • Cylinders and manifolds must be in a dedicated room. • Piping and equipment should be sized to accommodate future growth. • Numerous requirements for valves and alarms. • Medical vacuum pumps, medical air compressors and alarms must be connected to the essential power system. 77
Summary • Service interruptions must be carefully coordinated and scheduled. • Installers must be qualified. • Brazing is required for Level I and Level 2 systems. • Tubing must be delivered cleaned and capped. • Pressure gas tubing must be ASTM B 819 hard drawn copper. • Materials must be stored in a suitable manner. • Everything must be labeled. • All systems must be tested by the installer.
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Summary • All systems must be thoroughly tested by a third party prior to use. • Documentation is critical. • Maintenance staff must be properly trained. • Special precautions are necessary. • Preventative maintenance is required. • Alarms must be periodically tested.
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Further Study • NFPA 99, Health Care Facilities Handbook (2005 Edition available on 4/1/05) • AIA Guidelines for Design and Construction of Health Care Facilities • ASPE Data Book, Special Plumbing Systems, Chapter 2 • FDA Public Health Advisory, Guidelines for Hospitals, Nursing Homes, and Other Health Care Facilities • Healthcare Plumbing and Piping: New Designs for WAGD Systems by Mark Allen, Beacon Medical Products 80
