designing for success what about purging and flushing
TRANSCRIPT
DonPenn,PE,CGDImageEngineering Group,Ltd
DESIGNING FOR SUCCESSWHAT ABOUT PURGING AND
FLUSHING
Commercial Applications
Learning Objectives• Discuss the importance of proper piping
design to accommodate purging and flushing.
• Discuss design considerations to facilitate flushing and purging.
• Discuss the potential benefits of different design features.
• Introduce new IGSHPA Inspectors Course
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Outline/Agenda
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q ImproperFlushingandPurgingandpipedesign/sizingcanbreakanotherwisepotentiallysuccessfulproject……..
q Designphilosophyforflushingandpurging
q Pipesizingconsiderations.
q Valvelocationandlocationpreferencesandlimitations….
q Header/manifoldconsiderations
Protection/Purging of Piping
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• Duringallphasesoftheinstallationitiscriticalthatallpipingisprotectedfromdebrisandforeignobjectsenteringthepipe.
• Aftertheheatexchangeriscompletedthesystemshouldbepurgedofallairanddebris.
• Debriscanclogorfoultheheatexchanger• Entrainedaircancorrodemetalliccomponents,causenoise,andcanpossiblypreventflowinsectionsofthesystem.
• Trappedaircanbeseparatedfromwaterandthereforeremovedbypowerflushingthesystemataminimumflowvelocityof2feetpersecond(FPS).
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• Therearetwobasicflowregimesdefinedinfluidmechanicstodescribethenatureoffluidflowinanysituation:laminarandturbulent.Inthelow-velocitylaminarregime,fluidflowisstreamlinedandsmooth.Oncethefluidvelocityhasbeenincreasedaboveacriticalvalue,flowbecomeschaoticanddisorderedandentersintotheturbulentregime.
• Themixingoffluidinturbulentflowmaximizestheheattransfercapability.
• Ground-looppipingshouldbesizedsuchthatfluidflowthrougheachloopisturbulenttoensuremaximumheattransfer.
• Turbulentflowcanalsoproducehigherlevelsoffrictionbetweenthefluidandpipewalls,pressuredropneedstobeevaluatedtominimizepumpHP.
Sizing Considerations
FLUSHING, PURGING AND FLOW TESTING
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Ø Beforethesystemisplacedinoperation,flushingofallheatexchangerpipingshallbeperformedtoremovedebrisandair.
Ø Flushingshallbeperformedat135%ofdesignflow,butinnocaselessthan2FPS.
ØEachsubfieldshallbeseparatelyflushedandpurgedØLaststageofflushingandpurgingshouldbethrutheunitheatexchanger;heatexchangersshouldbebypasseduntilpipingsystemisflushedandpurged.
ØAclosedloop-flushingunitwithavolumetankfiltersshallbeutilized.ØTheflushingvolumeshallbeatleast3xthe systemvolume