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FLOW IN PIPE NETWORKS
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C11
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ISSUE 11
DECEMBER 1999
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ARMFIELD LIMITED
OPERATING INSTRUCTIONS AND EXPERIMENTS
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C11 FLOW IN PIPE NETWORKS
PAGE NO.
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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
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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.
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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
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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.
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Manometerconnections
Remoteprobeswith air bleedvia ventedball valve
Manifolds
Various with self sealingpressuretappingswhere applicable.
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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
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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.
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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
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C11 FLOW IN PIPE NETWORKS
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
""
(
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Test p lpe
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HI .. - - .-i
Control1ed
water
M
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f1ow rate from
Hydrau1ic Bench (0) ~,- - - - ~
/
Probe
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-- .
II
.:
II
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Test Pipe Sequence
Manometer
, stand
",
,,
,,
., . ...
1.
2.
3.
0
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.
.
".
-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.
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C11 FLOW IN PIPE NETWORKS
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.
C11 FLOW IN PIPE NETWORKS
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.
~
C11 FLOW IN PIPE NETWORKS
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
C11 FLOW IN PIPE NETWORKS
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.
C11 FLOW IN PIPE NETWORKS
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
C11 FLOW IN PIPE NETWORKS
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)
~
C11 FLOW IN PIPE NETWORKS
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