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TheDuctDesignProcess
DuctDesignReferenceBooks
AvailableStaticPressure
EquivalentLength
FrictionRate
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Fittingsdominatepressuredrops…
Poorlyinstalledflexductcanbejustasbadforairflow
FromFantasytoReality
DuctLayout
DuctLayout
DuctLayout
DuctLayout
DuctLayout
FifthEdition
“Installductfullyextended,donotinstallinthecompressedstateoruseexcesslengths.Thiswillnoticeablyincreasefrictionlosses”.
AirDuctCouncilFlexibleDuctPerformance&InstallationStandards
InstallationGuidelines
PressureDropResearch
Air
BlowerNozzle
Chamber
Temperature T1Temperature T2
Entry Duct> 10 Dd
Temperature T3
PiezometerRings
Test Duct
Exit Duct> 4 Dd
VSD
Air
BlowerNozzle
Chamber
Temperature T1Temperature T2
Entry Duct> 10 Dd
Temperature T3
PiezometerRings
Test Duct
Exit Duct> 4 Dd
VSD
DataAcquisition(DAQ)setup
• ANSI/ASHRAEStandard120requirementswereusedtodesignthesystemandprocessthedataafteracquisition.
ANSI/ASHRAEStandard120TestingProtocol
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ComputationalFluidDynamics(CFD)ComputerGeneratedModelofAirFlowinFlex
v/U: 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3
ComputationalFluidDynamics(CFD)ComputerGeneratedModelofAirFlowinFlex
TheNewASHRAEDuctCalculator
QuickReferenceTool
LaboratoryDatacomparedwithin10%ofcalculatedvalues,soASHRAEpublishedformulaswereusedto
createthistool.
CompressionGraphic
PGQ$&*
RoundSheetMetalDuctvsFlexibleDuct4%,15%,30%Compression
200cfm /650fpm
8”RoundSheetMetalDuct=9”FlexibleDuctat4%compression
.08”-.09”FrictionLoss
8”RoundMetalDuct=10”FlexibleDuctat15%Compression,12”FlexibleDuctat30%Compression
IsRigidDucttheAnswer?
UniformMechanicalCode
603.4.1LengthLimitation. Factory-madeflexibleairductsandconnectorsshallbenotmorethan5feet(1524mm)inlengthandshallnotbeusedinlieuofrigidelbowsorfittings.Flexibleairductsshallbepermittedtobeusedasanelbowataterminaldevice.Exception: Residentialoccupancies.
81/1,234
FlexDuctSystemsThatWork
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AdvantagesofFlexDuct
• Options• Cost• Noisecontrol• Energyefficiency
Butithastoinstalledproperly!
93/1,471,412
AlwaysCarryFlexDuct!
Questions?
Lastone
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