4 The Foibles, Follies and Fixes of Flex...4_The Foibles, Follies and Fixes of Flex Created Date 20170806173519Z ...

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The2CausesofReducedAirFlow

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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

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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.

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FlexDuctSystemsThatWork

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AdvantagesofFlexDuct

• Options• Cost• Noisecontrol• Energyefficiency

Butithastoinstalledproperly!

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AlwaysCarryFlexDuct!

Questions?

[email protected]

[email protected]

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