C11 Flow in pipe networks

~

FLOW IN PIPE NETWORKS

n C11

I I-';

C

ISSUE 11 DECEMBER 1999

~

n ARMFIELD LIMITED OPERATING INSTRUCTIONS AND EXPERIMENTS

-

C11 FLOW IN PIPE NETWORKS

PAGE NO.

g ~

SAFETY

1

INTRODUCnON

5

RECEIPTOF EQUIPMENT

6

DESCRlPnON

8

INSTALLA nON REQUIREMENTS ASSE:rvIBLY

I

12

CONNEcnON TO SERVICES

13

CO~SSIONING

14

ROUTINE MAINTENANCE

21

INDEX TO EXPERIMENTS

22

GENERALSAFETY

I

11

a

SAFETY IN THE USE OF EQUIPMENT SUPPLIED BY ARMFIELD Before proceeding to install, commission or operate the equipment described in this instructionmanualwe wish to alert you to potential hazardsso that they may be avoided. Although designedfor safeoperation,any laboratoryequipmentmay involve processesor procedureswhich are potentially hazardous.The major potential hazardsassociatedwith this particular equipmentare listed below.

.

INJURY nlROUGH MISUSE INJURY FROM ELECTRIC SHOCK

.

INJURY FROM INCORRECT HANDLING

.

POISONING FROM TOXIC MA1ERIALS (E.G. MERCURY)

RISK OF INFEcnON THROUGH LACK OF CLEANLINESS Accidents can be avoided provided that equipmentis regularly maintained and staff and students are made aware of potential hazards.A list of general safety rules is includedin this manual,to assiststaff and students in this regard.The list is not intended to be fully comprehensivebut for guidanceonly. Pleaserefer to the notes overleaf regarding the Control of SubstancesHazardousto HealthRegulations.

The COSHH Regulations The Control of SubstancesHazardousto Health Regulations(1988) The COSIffi regulationsimpose a duty on employersto protect employeesand others from substancesusedat work which may be hazardousto health. The regulationsrequire you to make an assessmentof all operationswhich are liable to exposeany person to hazardoussolids, liquids, dusts,vapours,gasesor micro-organisms.You are also required to introduce suitable proceduresfor handling these substancesand keep appropriate records. Since the equipment supplied by Armfield Limited may involve the use of substances which can be hazardous(for example,cleaningfluids used for maintenanceor chemicals used for particular demonstrations)it is essentialthat the laboratory supervisoror some otherpersonin authority is responsiblefor implementingthe COSlllI regulations. Part of the aboveregulationsare to ensurethat the relevantHealth and SafetyData Sheets are available for all hazardoussubstancesused in the laboratory. Any person using a hazardoussubstancemust be informed of the following: Physicaldataaboutthe substance Any hazardfrom fire or explosion Any hazardto health AppropriateFirst Aid treatment Any hazardfrom reactionwith other substances How to clean/disposeof spillage Appropriateprotectivemeasures Appropriate storageand handling Although these regulations may not be applicable in your country, it is strongly recommendedthat a similar approach is adopted for the protection of the students operatingthe equipment.Local regulationsmust also be considered. Water-BorneInfections The equipmentdescribedin this instruction manualinvolves the useof water which under certain conditions can create a health hazard due to infection by hanDful microorganisms. For example,the microscopicbacteriumcalled Legionella pneumophilawill feed on any scale,rust, algaeor sludgein water and will breed rapidly if the temperatureof water is between20 and 45°C. Any water containingthis bacteriumwhich is sprayedor splashed creatingair-bornedropletscan producea form of pneumoniacalled LegionnairesDisease which is potentially fatal.

2

Legionellais not the only harmful micro-organismwhich can infect water, but it servesas a useful exampleof the needfor cleanliness. Underthe COSmI regulations,the following precautionsmust be observed:Any water containedwithin the product must not be allowed to stagnate,i.e. the water must be changedregularly. Any rust, sludge, scale or algae on which micro-organismscan feed must be removed regularly,i.e. the equipmentmust be cleanedregularly. Wherepracticablethe water shouldbe maintainedat a temperaturebelow 20°C or above 45°C. If this is not practicable then the water should be disinfected if it is safe and appropriateto do so. Note that otherhazardsmay exist in the handling of biocidesusedto disinfect the water. A schemeshould be preparedfor preventing or controlling the risk incorporating all of the actionslisted above. Further details on preventing infection are containedin the publication "The Control of Legionellosisincluding LegionnairesDisease"- Health and Safety Seriesbooklet HS (G) 70.

3

USE OF EARTH LEAKAGE SAFETY DEVICE

CIRCUIT BREAKER AS AN ELECTRICAL

The equipment described in this Instruction Manual operatesfrom a mains voltage electrical supply. The equipment is designed and manufactured in accordancewith appropriateregulations relating to the use of electricity. Similarly, it is assumedthat regulationsapplying to the operationof electricalequipmentare observedby the end user. However,to give increasedoperatorprotection, Annfield Ltd have incorporatedan Earth LeakageCircuit Breaker (ELCB, alternatively called a ResidualCurrent Circuit Breaker or RCCB) as an integral part of this equipment. If through misuse or accident the equipmentbecomeselectrically dangerous,an ELCB will switch off the electrical supply and reducethe severity of any electric shock receivedby an operator to a level which, undernormal circumstances,will not causeinjury to that person. At least once each month, check that the ELCB is operating correctly by pressingthe TEST button. The circuit breakerMUST trip when the button is pressed.Failure to trip meansthat the operatoris not protectedand the equipmentmust be checkedand repaired by a competentelectricianbeforeit is used.

4

INTRODUCTION A commonproblem in pipeline hydraulicsis the determinationof the pressuresand flows in a system of interconnectedpipes, often known as a "pipe network". Such networks range from a single pipe to complex systemsinvolving many pipes of different lengths and diameters, and incorporating distributed off-tube and supply points. A town water supply is a good example of a very complex network. A good understandingof the behaviourof pipe networks and the ability to predict flow and pressuredistributionsare essentialin the designof systemsfor the transportationof fluids. The Armfield Flow in Pipe Networks is specifically designedto allow the setting up of a wide range of pipe arraysand the measurementof the flows andpressuresusing water asthe fluid.

5

~

RECEIPT OF EQUIPMENT 1.

SALES.IN THE UNfl'ED KINGDOM The apparatusshould be carefully unpackedand the componentscheckedagainst the Advice Note. A copy of the Advice Note is supplied with this instruction manualfor reference. Any omissionsor breakagesshould be notified to Armfield Limited within three daysof receipt.

2.

SALESOVERSEAS The apparatusshouldbe carefully unpackedand the componentscheckedagainst the Advice Note. A copy of the Advice Note is supplied with this instruction manualfor reference. Any omissions or breakagesshould be notified immediately to the Insurance Agent statedon the msuranceCertificate if the goods were insured by Annfield Limited. Your own insurers should be notified immediately if insurancewas arrangedby yourselves.

'

;I ,

:

If, '

6

DESCRIPTION The water supply and measurementmodule is basedon the Annfield hydraulics bench which is proven as a servicefacility. The bench comprises of upper and lower G.R.P. mouldings in contrasting colours, designedfor durability and freedomfrom maintenance.The lower moulding incorporates a water storagesump tank from which a self-priming centrifugal pump delivers water to the systemunder examination.The upper moulding incorporatesa volumetric measuring tank which is steppedto allow the measurementof both high and low flow rates, the water level being indicatedby a remotesight tube and scaleon the bench front. A stilling baflle reducesdisturbancein the volumetric tank and a dump valve in the basereturnsthe measuredwater to the sumptank for recycling. The top of the benchis fitted with a metal supportingframe for the pipe networks and for the inlet manifold which is common to any selectedsystem.Five pipe lengths in three diametersare supplied; and a wide range of series,parallel and mixed configurations is possible using the interconnectingfittings, also supplied. Fittings are readily assembled with screwedcouplings sealedwith O-rings. Pressuredifferencesbetweenpoints in the system are measuredwith 'u' tube manometers;water for the lower differences and mercuryfor the higher. Self sealingpressuretapping points are provided in the fittings to which connectionis madevia probesand flexible tubes. Air in the manometerconnectingtubesis automaticallybled from stopcocksusedto shut off the manometers.The interchangeablelength of pipe and interconnectingfittings are storedon a boardattachedto one end of the bench. NOTE: To connecta test probe to a pressmepoint, simply push the tip of the test probe into the pressmepoint until it latches.To disconnecta test probe from a pressmepoint, pressthe metal clip on the side of the pressmepoint to releasethe test probe. Both test probe and pressmepoint will sealto preventlossof water.

8

TechnicalSpecifications: Testpipes 1 off 22.5mmI/D 2 off 11.5mmI/D 2 off 13.0mmI/D Commonlength = O.1m

Pump '1

-

Submersibletype Powerrating 0.55kW 2800 RPM Vo/umetric range

0-6 litres low level in gauge 0-40 litres high level in gauge

.I

Manometers 1 metrepressurisedwater manometer 1 metremercurymanometer

I. ~\

Manometerconnections Remoteprobeswith air bleedvia ventedball valve Manifolds Various with self sealingpressuretappingswhere applicable.

"1 f: .1

I

I f

~

:

";;~' Tf'~

9

Use of the mercury manometer A mercury manometer is supplied with this product to facilitate measurementof differential pressuresin the systemusing a fundamentaltechniquethat provides accurate readingswithout the needfor referencecalibration. The designof the manometerensuresthat once primed, the mercury is submergedbelow water preventing the escapeof harmful vapour. Catch pots at the rear of the manometer preventthe escapeof mercuryshouldthe measuringrangeof the manometerbe exceeded. Annfield can supply a portable digital pressuremeter that can be connectedin place of the mercurymanometerwhen local regulationsdo not allow the useof mercury. The product code for this meter is H12-8 and it is also available with a NPL 5 point calibration certificate (H12-8-CC1) or NAMAS 10 point calibration certificate (H12-8CC2) if required.

10

INSTALLATION REQUIREMENTS ELECTROMAGNEllC CaMP A TIBILffY This apparatus is classified as Education and Training Equipment under the ElectromagneticCompatibility (Amendment) Regulations 1994. Use of the apparatus outside the classroom,laboratoryor similar such place invalidates confonnity with the protection requirementsof the ElectromagneticCompatibility Directive (89/336/EEC) andcould leadto prosecution.

FACnmESREQUIRED The equipmentis designedfor floor standingin a static location and requiresa finn level floor. The equipmentrequiresconnectionto a single phase,fusedelectrical supply. Four metres of supplycableis suppliedwith the equipment. Installationcan be carriedout using a basictool kit. Overall dimensionsof the equipmentare:

HEIGHT LENGlH wmlH

1.3m O.78m 2.Om

It is a self-containedunit and needsonly a temporary supply of cold water for initial filling.

1

ASSEMBLY All numericalreferencesrefer to the diagramon page 16. Clamp the pipe network supportframe (15) to the top of the bench with the four long clamping bolts.

2.

Attach the angle bracket(14) which carriesthe air bleed valves to the benchwith the remaining clamping bolt, and to the pipe network support frame (15) with the M4 x 15mmlong bolt.

3

Placethe inlet manifold frame (9) onto the pipe network support frame and clip into position.

4.

Connectinlet manifold (9) to pump usingthe flexible tubing provided.

s.

Connectthe four straight test pipesto the inlet manifold and clamp the tubes into position using the clamps(17)

6.

Connectthe outlet manifold (16) to the test pipes with the dischargetube in the volumetric tank. Ensure that all couplings betweenthe manifolds and test pipes aretightened.

Assemblyof Manometers 1

Clamp the basesupportstandto the main frame with the bolts provided.

2.

Clampthe two manometersto the main frame with the mercury manometeron the left hand side of the frame. NOTE:

There are 2 spacersfor the water manometerbut only I for the top of the mercurymanometer.

Connectionsbetweenthe manometers,the air bleed valves on the bench top, and the pressuretest probes should be effectedusing the flexible tubing provided in accordance with the manometerconnectiondiagramon page 19. Whenpositioningthe manometerstandtake carenot to over-stretchthe flexible length of tubeswhenyou connectthem to the module andthe manometers.

12

CONNECTION TO SERVICES ELECTRICALSUPPLYFOR VERSIONCII-A: The equipment requires connection to a single phase, fused electrical supply. The standardelectrical supply for this equipmentis 220/240V, 50Hz. Check that the voltage and frequencyof the electricalsupply agreewith the label attachedto the supply cableon the equipment.Connectionshouldbe madeto the supplycableas follows:GREEN/YELLOW BROWN BLUE FuseRating

EARnI LIVE (HOT) NEUTRAL 13 AMP

ELECTRICALSUPPLYFOR VERSIONCII-B; The equipment requires connection to a single phase, fused electrical supply. The standardelectrical supply for this equipmentis 120V, 50Hz. Check that the voltage and frequencyof the electrical supply agreewith the label attachedto the supply cable on the equipment.Connectionshouldbe madeto the supply cableas follows:GREEN/YELLOW BROWN BLUE FuseRating

EARnI LNE (HOT) NEUTRAL 25 AMP

COLD WATER The equipmentis self-containedand does not require permanentconnectionto a water supply. An initial supply of cold water will be required to fill the sump tank. Water will also be requiredfor cleaning/flushingafter use. DRAIN (COLD WATER) The equipment is self-containedand does not require a drain for nonnal operation. A drain will be requiredfor cleaning/flushingpurposes.

13

COMMISSIONING All numericalreferencesrefer to the drawing on page 19.

1.

Closethe drain valve (4) in the baseof the sumptank. Placethe water supply hose into the volumetric tank (1), lift the dump valve (2) with a twist motion of 90°, this will hold the valve in the openposition.

2.

Turn on the water and fill the sump tank (3) via the volumetric tank. When full ensurethat the water level in the swnp tank is below the outlet in the bottom of the volumetric tank.

3.

Turn off the water at the supply, open drain valve (4) and empty the sump,this is to remove any particles of foreign matter residing in the tank. Close the drain valve and refill the sumptank. Turn off the water and removethe hose.

4.

Placethe stilling baft1e(6) into the volumetric tank ensuringthat the upper edge of the baft1eis in line with the exit of the openchannel. Connectthe electrical supplyto the bench.

s.

Checkthe operationof the RCD by pressingthe Test button (refer to page4). The RCD must trip when the Test button is pressed.Resetthe RCD.

6. 7.

Switch on starter(7) and check that pump (8) is operating satisfactorily, and that water is reachingthe inlet manifold (9) from the sumptank. Switch off.

8.

Connectall the test pipes into their positions as shown on page 19. Open valves VI, V2, V3 and V 4 respectivelyand observedischargeinto volumetric tank of eachvalve in turn, with valve (13) open.

9.

Checkfor leaks.

NOTE:

To connecta test probe to a pressurepoint, simply push the tip of the test probe into the pressurepoint Wltil it latches.To disconnecta test probe from a pressurepoint, pressthe metal clip on the side of the pressurepoint to releasethe test probe. Both test probe and pressurepoint will seal to preventloss of water.

14

Commissioningof the pressurisedwater manometerand mercurymanometercan only be carried out after the general commissioning of the equipment has been completed (describedon page 14).

Commissioning the Pressurised Water Manometer Pleaserefer to the Manometer ConnectionDiagram on page 19 for the nomenclature usedin this text. ConnectprobeC to the pressuretapping(10) on the upstream(inlet) manifold. ConnectprobeD to the pressuretapping(12) on the downstream(outlet) manifold. Close bleed valves C and D on the top of the volumetric tank (handle at 90° to valve body). Openisolating valves VI, V2, V3 and V 4 on the test pipes. Openthe outlet flow control valve (13) below the outlet manifold. Closethe inlet flow control valve locatedbelow the inlet manifold. Start the pump then gradually open the inlet flow control valve to allow water to flow throughthe test pipes and into the volumetric tank. Partially closethe outlet flow control valve to reducethe water flow slightly and pressurisethe system.Water will discharge into the volumetric tank through a vent hole on the undersideof each bleed valve thus purging air from the flexible tubing to the test probes. To prime the manometerwith water, undo coupling D (connectedto the downstream tapping) on the manometerside of the bleed valve bracketand place the free end of the tubing from the manometerin the volumetric tank. Open bleed valve C and allow water to flow from the upstreamtapping, through the manometerand into the volumetric tank. When all air bubbles have been purged from the manometerclose bleed valve C then reconnectthe tubing to coupling D. Note: To ensurethat the manometerremainsfully primed ensurethat both bleed valves areclosedbeforedisconnectingeither probe from the pressuretappings.The bleed valves shouldnot be openedagain until both probesare connectedto appropriate pressuretappings. The manometercan be operatedusing the following sequence: Closeboth bleedvalves (C and D) so that water dischargesfrom eachbleedvalve into the volumetrictank. Disconnecteachprobe from its original pressuretapping by pressingthe metal clip on the side of the pressuretapping.

15

Reconnectboth probesto the requiredpressmetappingson the equipmentby pushingthe tip of the probe into the tapping until it latches.Water will automaticallydischargefrom the vent on eachbleedvalve. Wait until all air has beenpurgedfrom the flexible tubing, indicated by a steadyflow of water from eachvalve. Openboth bleed valves (C and D). Allow the readingon the manometerto stabilisethen recordthe level of the water (bottom of the meniscus)in eachmanometertube. Closeboth bleed valves (C and D) after taking the reading.Stepsb), c), d) and e) should be repeatedas required to eliminate air from the manometerand flexible tubing while taking measurements. The water manometer can be pressurisedto allow small differential pressuresto be measuredwhen static pressureat the tappingsis high or low. This condition is indicated by the level in both tubesbeingat the top or bottom respectively. If the water level in both tubes is at the top then the systempressureis high and the manometermust be pressurlsedto bring the levels to mid range on the manometer. Removethe cap from the Schraderconnectionon the bottom manifold block and connect the hand pump. Pump slowly until both water levels are on the scale, preferably equidistant from mid position to allow different pressuresto be measuredwithout pressurlsingthe manometeragain. Before taking readingsdisconnectthe hand pump to preventchangesto the levels dueto leakageof air. If the water level in both tubes is at the bottom then the systempressureis low and the manometermust be de-pressurised to bring the levelsto mid rangeon the manometer. Carefully open the bleed screw on the top manifold block to allow air to enter the manometeruntil the water levels are central on the scale.Ensurethat the bleed screw is tightenedto preventleakage. If water flows continuouslythrough the manometerand a stablelevel cannotbe achieved in both tubes then it is likely that the differential pressureexceedsthe range of the manometer.It will be necessaryto connectthe mercury manometerin place of the water manometerto measurethis pressuredifference.

16

Commissioning the Mercury Manometer To ensuresafe and accurateoperationof the mercury manometerthe following priming procedureshouldbe adopted. Pleaserefer to the Manometer ConnectionDiagram on page 19 for the nomenclature usedin this text. ConnectprobeA to the pressuretapping(10) on the upstream(inlet) manifold. ConnectprobeB to the pressuretapping(12) on the downstream(outlet) manifold. Close bleed valves A and B on the top of the volumetric tank (handle at 900 to valve body). Openisolating valvesVI, V2, V3 and V4 on the test pipes. Openthe outlet flow control valve (13) below the outlet manifold. Closethe inlet flow control valve locatedbelow the inlet manifold. Start the pump then gradually open the inlet flow control valve to allow water to flow throughthe test pipes and into the volumetric tank. Partially closethe outlet flow control valve to reducethe water flow slightly and pressurisethe system.Water will discharge into the volumetric tank through a vent hole on the undersideof each bleed valve thus purging air from the flexible tubing to the test probes. Before filling the manometerwith mercury it will be necessaryto prime the manometer with water. Undo coupling B (connectedto the downstreamtapping) on the manometer sideof the bleedvalve bracketandplacethe free end of the tubing from the manometerin the volumetric tank. Open bleed valve A and allow water to flow from the upstream tapping,throughthe manometerand into the volumetric tank. Partially unscrewthe fitting at the top of eachcatchpot (at the rear of the manometer)to allow any trappedair to escape.Ensurethat the fittings are tightenedagain. When all air bubbleshave beenpurged from the manometer(including the tubes and catchpots at the rear) closebleedvalve A then reconnectthe tubing to coupling B. Ensurethat both bleedvalves are closedthen removeboth of the screwedplugs from the top manifold on the manometer.Using a small funnel (not supplied) carefully pour clean mercury (not supplied) into one of the manometer tubes. As the mercury fills the manometerwater is displaced from the filling point ensuring that no air is entrained. When the mercury is at the required level, half way up the measuringscale,replaceand tighten the two screwedplugs.

17

To ensurethat the manometerremainsfully primed ensurethat both bleed valves are closedbeforedisconnectingeitherprobefrom the pressuretappings.The bleed valves should not be openedagain until both probesare connectedto appropriate pressuretappings. The manometercan be operatedusingthe following sequence: Closeboth bleedvalves (A and B) so that water dischargesfrom eachbleedvalve into the volumetric tank. Disconnecteachprobe from its original pressuretapping by pressingthe metal clip on the side of the pressuretapping. Reconnectboth probesto the requiredpressuretappingson the equipmentby pushingthe tip of the probe into the tapping until it latches.Water will automaticallydischargefrom the vent on eachbleedvalve. Wait until all air has beenpurged from the flexible tubing, indicated by a steadyflow of water from eachvalve. Openboth bleed valves (A and B). Allow the readingon the manometerto stabilisethen recordthe level of the mercury(top of the meniscus)in eachmanometertube. Closeboth bleedvalves (A and B) after taking the reading. Stepsb), c), d) and e) should be repeatedas required to eliminate air from the manometerand flexible tubing while taking measurements. Mercury is a poison and great care should be used when handling. Any spillages when handlingthe mercurymust be collectedimmediately. The manometer incorporates catch pots to retain the mercury if the range of the manometeris accidentally exceeded.It is suggestedthat the mercury is collected in a vesselfilled with water if it is necessaryto recoverthe mercury from the catch pots. The vesselshould be large enoughto contain the lower end of the manometerto prevent loss of mercurywhen the drain plug on the catchpot is unscrewed.

18

~

ROUTINE MAINTENANCE To preservethe life and efficient operation of the equipment it is important that the equipmentis properly maintained.Regularservicing/maintenance of the equipmentis the responsibility of the end user and must be performed by qualified personnel who understandthe operationof the equipment. In addition to regularmaintenancethe following notesshouldbe observed:Disconnectthe equipmentfrom the electricalsupply when the equipmentis not in use.

2.

If the equipment is likely to stand idle for a considerabletime, drain the water from the sumptank using the drain cock provided.

3.

Cleanall the equipmentthoroughlyafter use.

-

I

:1

21

-

C11 FLOW IN PIPE NETWORKS INDEX TO EXPERIMENTS

PageNo.

Experiment

HEAD LOSS AGAINST DISCHARGE CHARACTERISnCS

A-I

CHARACTERlSllCS OF A PIPENETWORK SYSTEM IN PARALLEL

B-1

CHARAClERIsncs OFA PIPENETWORKSYSlEM IN SERIES

C-I

CHARACTERlSllCS OF A RING MAIN, WUH ONE INLET AND 'mREE O~TS

D-I

DOUBLING OF PIPES

B-

22

~


EXPERIMENT A OBJECTOF EXPERIMENT: To determine the head loss versus dischargecharacteristicsfor each of the three different diameter test pipes supplied as network components.

Dischargeto

EQUIPMENT SET-UP:

volumetric measuring

In1et Manlfo1d

""

(

I J-

~

Test p lpe

I.~

/

.

~

HI .. - - .-i

Control1ed water

M

~I

f1ow rate from

Hydrau1ic Bench (0) ~,- - - - ~

/ Probe

~

-- .

II

.:

II

- -.

Test Pipe Sequence

Manometer , stand

",

,,

,,

., . ...

1. 2. 3.

0 I .

.

".

-EH

:

Probe.

Q~ - - -D-Q-~: . . :

.-f2

~H

_t.

,

,- -

.

.

,.'

.,

I

Measured on water or mercury s~a1eto suit I ,,

-.

-

13 mm dia. 17.5mm dia. 22 mm dia.

SUMMARY OF THEORY:

H..

HydrautIc Grade line H2

Any pipeline of diameter (D) and length (L) carrying a flow rate (Q) within a network will have a head loss along its length (AH

= HI - HJ. This headlossis

largely the result of pipe friction and:

a O.

L

.LQ2 Frictionheadloss= KDs

Other lossesarise from junctions, bends, valves or sudden change of pipe section.

tank

C11 FLOW IN PIPE NETWORKS READINGS TO BE TAKEN;

Connect up the equipment as shown in the schematic diagram using the 13.Ommdiameter test pipe. Switch on the hydraulic benChpump and open the flow control valve to allow a nominal flow through the pipe. Note the head loss across the pipe on the appropriate manometer scale and determine the volumetric flow rate using the hydraulic bench measuring tank and stopwatch. Repeat this procedure for a range of increasing flow rates. Once completed, the test pipe should be replaced with each of the remaining pipes in turn and the whole procedure repeated as above. RESULTS: Pipe dia. mm

Hl-2

Voll

Time Sec

Flow l/Sec The table of results should be used to plot a set of curves representing the total head loss versus volumetric flow rate characteristics for eochtEStpipe arrangement.

13.0

17.5

22.0

Note: The curves should be plotted carefully as they will be necessaryfor the analysis of other Flow in Pipe Networks Experiments concerned with the determination of pressure head and flow relationships in parallel pipe networks, doubled pipe arrangementsand ring mains

Tota1 head 10ss H 1-2

Vo1umetr1cflow rate (0) Students should comment upon the observed relationship between head loss and the flow rate for eachtest pipe.

~


EXPERIMENT B OBJECTOF EXPERIMENT: To determine the characteristicsof a pipe network consisting of four pipes of various sizes in parallel. EQUIPMENT SET-UP: Inlet Manifold

EXit Manifold

13mm DiDe

Dischargeto volumetric measuringtank

""

I

H2

HI

--< Ii

~:-:Controlled water ~ fJow rate from' . Hydraulic

Bench

(0)

/

Probe

"

, I,.

Manometer . stand

,.

-~

.,

,

,

SUMMARY OF THEORY:

'--

-,

--...

.

.J

[.

.

j

""I ~H

. .

Probe

Measuredon water or mercury scale to suit ,

.-

.

,'

,.

In a pipe network consisting of four pipes of various diameters (Dt D2D3 DJ and lengths (Lt L2 ~ LJ in parallel with each other, the pressure in the common junction manifolds must be the same for all four pipes. The total flow (~) therefore distributes itself between the four branch pipes in accordance with the controlling end pressures and:-

QT=Q. +Q2+~+Q. INITIAL VALUES OF VARIABLES TO BE USED: 01

I

=13mmdia., O2= 17.5mmdia., 03 = 22mm dia., 0.=

13mm dia.


READINGS TO BE TAKEN: Connect up the equipment as shown in the schematic diagram. Switch 0 n the hydraulic bench pump and open the flow control valve to allow a nominal flow through the pipe network. Note the head loss across the network on the appropriate manometer scale and determine the volumetric flow rate using the hydraulic bench measuring tank and a stopwatch. Repeatthis procedure for a range of increasingflow rates. RESULTS:

Results Test No

HJ-2

Voll

Calculations Time sec

Flow l/sec

Q]

l/sec

Q2 l/sec

~

Q. l/sec l/sec

I,Q l/sec

Students should determine the flow in each branch pipe using the respective calibration curves for each individual size of pipe used. Note:

These calibration curves must be determined prior to this experiment and the procedure is fully explained on Data Sheet A 'Calibration of Network Components'. The flows in each branch pipe should be added together and the result compared to the total flow measured using the hydraulic bench. Correlation will be noted between the total flow values determined by these two experimental approachesbut students should account for any observed minor differences.

Students should observe and comment upon the magnitude of the flow rates in each pipe and account practically for their respective differences. Advanced students should calculate the theoretical flow rate in any pipe for a given head difference from a knowledge of the pipe geometry and an estimated pipe friction factor. The values so calculated should be compared to the experimentally determined values. Students should suggestpractical situations where parallel pipe networks might be found. Note:

This experiment may be repeatedfor alternative networks of only two or three pipes in parallel by connecting an appropriate network arrangement.

~


EXPERIMENT C OBJECTOF EXPERIMENT: To determine the characteristicsof a pipe network consisting of three pipes of different sizes in series. EQUIPMENT SET-UP: EX1t Manifo1d

Inlet Manifold

"" ~

-

-

1

22mm plpe

H2

3mm p1pe ""

I

I'

. .. 11---...a--

H

".~ ~cc.

I

DIschargeto volumetric measur1ngtank

i

Q,

-Controlledwater 41owrate from Jydpau11c Bench(0)

7.5mm pipe

. I --- ~. ... 1/ . . .

H4

a .

c

--- ~ . 4/ --- .I

/, /, prObe:

Outlet ,

I'" Probe, CoupIer

--""1

Manometer ~,stand ~ . ,~

-,

-- . .. .

Measuredon water or mercury

,. ~

'- '

SUMMARY OF THEORY: HydrauJ jc Grade 1;ne ~

-

H-

~

L.

a

2 ~-~

. I . I .

- -"-cH

. I . I . . .

,

,:

~H

:1

rHr

~

i~ 4

scale .

--

,.

to suit

A pipeline consisting of various diameter(Dt D2 DJ and lengths (Lt ~ LJ carrying a flow rate (Q) will have a total head loss (HT>along the whole length given by: HT= H1-2+ ~.3 + Hw

The component head loss from each section is the summation of the pipe friction loss plus other lossesarising from changes of section, junctions, bends and valves in that section.

pIpe


INITIAL VALUES OF VARIABLESTO BE USED: 01

= 13mm dia., D2= 22mm dia., D3= 17.5mmdia.

READINGS TO BE TAKEN: Connect up the equipment as shown in the schematic diagram. Switch on the hydraulic bench pump and open the flow control valve to allow a nominal flow through the pipe network. Connect the remote probes across each pipe section in turn and measure the head loss on the appropriate manometer scale.Measure the total head loss across the complete pipe network and determine the volumetric flow rate using the hydraulic bench measuring tank and a stopwatch. Repeat this procedure for a range of increasing flow rates. RESULTS: Test No "1-2

H1.-3

"3-4

IAH

HI-4

VOLt

TIME sec

FLOW 1/S8:

Students should interpret the results to verify for themselves, that the total head loss acrossthe seriesnetwork (Ht-4)is equal to the sum of the 3 component head losses(AI.H= Ht-2 + ~-3 + H~) for all flow rates. Students should observe and comment upon the magnitude of the 3 component head losses and account practically for their respective difference. Advanced students should calculate the theoretical head loss in any section for a given flow from a knowledge of the pipe geometry and an estimated pipe friction factor. The values so calculated should be compared to the experimentally measured values. Why is a knowledge of the energy degradation in a pipe network of importance to a system designer? Suggestpractical situations where series pipe networks might be found. Note:

This experiment may be repeated for an alternative network of only two different pipes in series by connecting an appropriate pipework arrangement.


EXPERll\IIENTD

OBJECTOF EXPERIMENT: To determine the characteristicsof a ring main supplied with water at one inlet point and supplying water at three outlet points. EQUIPMENT SET-UP:

\

17.Smm pipe H2

- ~-~-'

~J Controlled water

flow rate from

3 Dischargesto volumetric measuringtank

Outlet pipe

nlet Manifold

~

~. .-.

b.;e-4

.

Hydraulic Bench<0> '.

/", Probe

.

-

Manometer stand

--.

°out3

:H jut let pipes

13mm pipe

17.Smm pipe

.

I

b.H

~

'\PrObe . ,!

_t. , Measuredon water or mercury scale to suit , --

The solution of any ring main problem is to determine the head (H) at every junction point and the flow (Q) in every part of the ring from a knowledge of the supply quantity and the several quantities. Clearly for any junction point the algebraicsum of the flows must be zero: e.g. at point (3) Q2+~+~t3=O

INITIAL VALUES OF VARIABLESTO BE USED: 01

=17.5mmdia., O2= 22mm dia., 03 = 13mm dia., O.a= 17.5mmdia.

READINGSTO BE TAKEN: Connectup the equipment as shown in the schematic diagram. Switch on the hydraulic bench pwnp and open the flow control valve to admit a nominal flow to the ring main. Connect the remote probes acrosseach pipe in turn and measure the differential head on the appropriate manometerscale. Determine the total volwnetric flow rate from the three outlets using the hydraulic bench measuring tank and a stopwatch. This proceduremay be repeatedfor other flow rates if required.

FLOW IN PIPE NETWORKS

RESULTS; a) Results

Test No

Ht-2

"2-3

Vol 1

~H1..

Time sec

Flow l/sec

b) Calculations

Test No

Q2

Ql

l/sec

!!~

~

l/sec

Q. l/sec

~t2

l/sec

Oouu l/sec

~

L~t

l/sec l/sec

Students should determine the flow rate and direction in each pipe of the ring

main

(Ql

Q2 ~

~)

from the respective differential head

measurements.The flow rates may be deduced from the calibration curves for the various sizes of pipe used in eachsection of the ring. These calibration curves must be determined prior to this experiment and the procedure is fully explained on Data SheetA 'Calibration of Network Components'. The direction of flow in each pipe is determined by that of the falling pressuregradient. The outflow from each of the three dischargepoints should be calculated by adding algebraically the flows in each pipe meeting at that outflow. Finally, the three outflows should be added and compared to the measured inflow to check the measured inflow to check the validity of the ring analysis. Students should comment upon the distribution on flow around the ring and suggestpractical situations for the use of ring mains. Advanced students may wish to analyse the ring main theoretically and predict the flow and head distribution from a knowledge of ring geometry and basic assumptions regarding pipe friction factors and inlet conditions. Several methods are available, some using techniques of successive approximation. D-2

~

C11 FLOW IN PIPE NETWORKS EXPERIMENT E

OBJECTOF EXPERIMENT: To show that the flow carrying capacity of a pipeline is increased when the pipe is doubled by a parallel pipe for a part of its length.

.I

EQUIPMENT SET-UP:

Coupler

Inlet Manjfo1d

I

Coupler

Outlet pipe

\

3mm plpe .

bl

0-

H

HI

~:-~Controlled water ~

flow rate from

n Hydraulic

I Vo1umetric

22mm ptpe

~'-

/

.

, ,

"1

, Probe

n .~~

measuring

.

Bench (0) '--

l1

,-

I .

Manometer stand

Probe

- ""J: ~H

,. Measuredon water or

.

,, ~

.. - . -

.

. .

. .

,

mercury scale to suit

, I

',.,,

SUMMARY OF THEORY:

0

~.1

'~c

0.

~

03

t. a,

In order to increase the flow carrying capacity, a pipeline consisting of 2 sections of pipe having diameters (D1 OJ and lengths (L} LJ in series can be doubled over the length L1 by a parallel pipe having diameter D3 and length L3 for this network the following relationships apply:

Head loss along pipe 01 = head loss in pipe 01 + head loss in pipe O2

= head loss in pipe OJ + head loss in pipe O2

Flow rate O2 = Ql + ~ Length L1

=i.a

to tank


INITIAL VALUES OF VARIABLES TO BE USED:

I

Dt

= 13mm dia., D2= 22mm dia., D3 = 17.5mmdia.

READINGS TO BE TAKEN: Connect up the equipment up as shown in the diagram but with valve No.3 closed so as to connect a series pipeline only. Switch on the hydraulic bench pump and open the flow control valve to allow a nominal flow through the pipes. Note the head loss on the appropriate manometer scale and determine the volumetric flow rate using the hydraulic bench measuring tank and a stopwatch. Repeat this procedure for a range of increasing flow rates.

1\ ~

The whole procedure should next be repeatedbut with valve No.3 open so as to connect the doubled pipe circuit. RESUL TS:

a) Series pipeline only ~,

I

b) Doubled pipeline

I

Series pipeline only

Students should plot a curve of head loss versus flow rate for the two pipeline arrangements tested. The resulting graph will show the improved flow ca~g capacity of the doubled D~Ub1.ed pipeline. Students should comment upon the pipeline effect of doubling and suggestpractical situations where doubling might be used.

Flow rate (0)

~


Advanced students may wish to deduce theoretically the flow in each branch of the doubled pipe from: Q2 1 - Q2 3 0;-0:

and Q2=Q1 +~ assuming that the doubled pipes share the samefriction factor.

Q

I

GENERAL SAFETY RULES 1

Follow Relevant Instructions

a

Before attempting to install, commission or operate equipment, all relevant suppliers/manufacturers instructions and local regulations should be understood and implemented. It is irresponsible and dangerous to misuse equipment or ignore instructions, regulations or warnings. Do not exceed specified maximum operating conditions (eg. temperature, pressure,speedetc.)

b c 2 a

b

c

d e

f

g

Installation

Use lifting tackle where possible to install heavy equipment. Where manual lifting is necessarybeware of strained backs and crushed toes. Get help from an assistant if necessary.Wear safety shoes where appropriate. Extreme care should be exercisedto avoid damage to the equipment during handling and unpacking. When using slings to lift equipment, ensure that the slings are attached to structural framework and do not foul adjacent pipework, glasswareetc. When using fork lift trucks, position the forks beneath structural framework ensuring that the forks do not foul adjacent pipework, glassware etc. Damage may go unseen during commissioning creating a potential hazard to subsequentoperators. Where special foundations are required follow the instructions provided and do not improvise. Locate heavy equipment at low level. Equipment involving inflammable or corrosive liquids should be sited in a containment area or bund with a capacity 50% greater than the maximum equipment contents. Ensure that all servicesare compatible with the equipment and that independent isolators are always provided and labelled. Use reliable connections in all instances,do not improvise. Ensure that all equipment is reliably earthed and connected to an electrical supply at the correct voltage. The electrical supply must incorporate a Residual Current Device (RCD) (alternatively called an Earth Leakage Circuit Breaker - ELCB) to protect the operator from severeelectric shock in the event of misuse or accident. Potential hazards should always be the first consideration when deciding on a suitable location for equipment. Leave sufficient space between equipment and between walls and equipment.

3

Commissioning

a

Ensure that equipment is commissioned and checked by a competent member of staff before permitting students to operate it.

4

Operation

a

Ensure that students are fully aware of the potential hazards when operating equipment. Students should be supervisedby a competent member of staff at all times when in the laboratory. No one should operate equipment alone. Do not leave equipment running unattended. Do not allow students to derive their own experimental procedures unless they are competentto do so. Serious injury can result from touching apparently stationary equipment when using a stroboscopeto 'freeze' rotary motion.

b c

d 5

Maintenance

a

Badly maintained equipment is a potential hazard. Ensure that a competent member of staff is responsible for organising maintenance and repairs on a planned basis. Do not permit faulty equipment to be operated. Ensure that repairs are carried out competently and checked before students are permitted to operate the equipment.

b

6

Using Electricity

a

At least once eachmonth, check that ELCB's (RCCB's) are operating correctly by pressing the TEST button. The circuit breaker must trip when the button is pressed(failure to trip means that the operator is not protected and a repair must be effected by a competent electrician before the equipment or electrical supply is used). Electricity is the commonest cause of accidents in the laboratory. Ensure that all membersof staff and students respectit. Ensure that the electrical supply has been disconnected from the equipment before attempting repairs or adjustments. Water and electricity are not compatible and can cause serious injury if they come into contact. Never operate portable electric appliances adjacent to equipment involving water unless some form of constraint or barrier is incorporated to prevent accidental contact. Always disconnect equipment from the electrical supply when not in use.

b c

d

e

b

7

A voiding fires or explosion

a

Ensure that the laboratory is provided with adequate fire extinguishers appropriate to the potential hazards. Where inflammable liquids are used, smoking must be forbidden. Notices should be displayed to enforcethis. Beware since fine powders or dust can spontaneously ignite under certain conditions. Empty vessels having contained inflammable liquids can contain vapour and explode if ignited. Bulk quantities of inflammable liquids should be stored outside the laboratory in accordancewith local regulations. Storagetanks on equipment should not be overfilled. All spillages should be immediately cleaned up, carefully disposing of any contaminated cloths etc. Bewareof slippery floors. When liquids giving off inflammable vapours are handled in the laboratory, the area should be ventilated by an ex-proof extraction system. Vents on the equipment should be connected to the extraction system. Students should not be allowed to prepare mixtures for analysis or other purpose without competent supervision.

b c d e

f

g 8

Handling poisons, corrosive or toxic materials

a

Certain liquids essentialto the operation of equipment, for example mercury, are poisonous or can give off poisonous vapours. Wear appropriate protective clothing when handling such substances. Clean up any spillage immediately and ventilate areas thoroughly using extraction equipment. Bewareof slippery floors. Do not allow food to be brought into or consumed in the laboratory. Never use chemical beakersas drinking vessels. Where poisonous vapours are involved, smoking must be forbidden. Notices should be displayed to enforce this. Poisonsand very toxic materials must be kept in a locked cupboard or store and checked regularly. Use of such substancesshould be supervised. When diluting concentrated acids and alkalis, the acid or alkali should be added slowly to water while stirring. The reverse should never be attempted.

b c d e

9

A voiding cuts and bums

a

Take care when handling sharp edged components. Do not exert undue force on glass or fragile items. Hot surfaces cannot in most cases be totally shielded and can produce severe burns even when not 'visibly hot'. Use common senseand think which parts of the equipment are likely to be hot.

b

1

~

1 10

Eye protection

a

c

Goggles must be worn whenever there is a risk to the eyes.Risk may arise from powders, liquid splashes,vapours or splinters. Beware of debris from fast moving air streams. Alkaline solutions are particularly dangerousto the eyes. Never look directly at a strong source of light such as a laser or Xenon arc lamp. Ensure that equipment using such a source is positioned so that passers-bycannot accidentally view the source or reflected ray. Facilities for eye irrigation should always be available.

11

Ear protection

a

Ear protectors must be worn when operating noisy equipment.

12

Clothing

a

Suitable clothing should be worn in the laboratory. Loose garments can causeserious injury if caught in rotating machinery. Ties, rings on fingers etc. should be removed in these situations. Additional protective clothing should be available for all members of staff and students as appropriate.

b

b

Guards

a

Guards and safety devices are installed on equipment to protect the operator. The equipment must not be operated with such devices removed. Safety valves, cut-outs or other safety devices will have been set to protect the equipment. Interference with these devices may createa potential hazard. It is not possibleto guard the operator against all contingencies. Use common senseat all times when in the laboratory. Before starting a rotating machine, make sure staff are aware how to stop it in an emergency. Ensure that speed control devices are always set at zero before starting equipment.

b

c d

e 14

First aid

a

If an accidentdoes occur in the laboratory it is essential that first aid equipment is available and that the supervisor knows how to use it. A notice giving details of a proficient first-aider should be prominently displayed. A 'short list" of the antidotes for the chemicalsused in a particular laboratory should be prominently displayed.

b c

I

and safetydevices

13

d

C11 Flow in pipe networks

Recommend Documents