Greenheck Fan QEI-L Nail Gun User Manual


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7
Wheel Characteristics
Static Pressure
CFM
50%
Wheel
Width
50% Wheel Width
100%
Wheel
Width
100% Wheel Width
Intermediate
Wheel
Widths
Static Pressure
CFM
50%
Wheel
Width
50% Wheel Width
100%
Wheel
Width
100% Wheel Width
Intermediate
Wheel
Widths
Static Pressure
CFM
50%
Wheel
Width
50% Wheel Width
100%
Wheel
Width
100% Wheel Width
Intermediate
Wheel
Widths
Static Pressure
CFM
Class II
Class I
Belt Drive: Fan Class
ClassIandIIfanshavedifferentwheeldesignswithdifferentperformancecharacteristics.
ClassImixedflowwheelsareoptimizedforperformancesinvolvinglowpressuresandhighvolumes.ClassII
wheelsaredesignedforasteeperfancurvewithhigherpressurecapabilities.Thisisillustratedinthegraph
withthetwodifferentclasswheelsplottedatidenticalfanRPMs.
Whenselectingamixedflowfan,itcannotbeassumedthatmovingintoaClassIIfanwillproducethesame
resultsasaClassImixedflowfans.ModelQEI-LutilizesaClassIwheel.
Direct Drive: Percent Wheel Width
Directdrivemixedflowfansareoptimizedforperformancerequirementsbytheuseofpartialwidthwheels.This
isnecessarybecausethefanRPMiscommonlyfixedandidenticaltothemotorRPM.Areductioninthewidth
ofthewheel(ortheairpassage)resultsinreducedairflowcapacityandasteeperfancurve.Thisissimilarto
theeffectofareducedpitchinadirectdrivevaneaxialfan.QEIDwheelsareavailablein5%incrementsfrom
50-100%wheelwidth.
QEIDfanscanbeusedinconjunctionwithvariablefrequencydrives(VFD’s)forvariableairvolume(VAV)
systems.Intheseapplications,thewheelwidthisoptimizedtoensureefficientoperationandstable
performancethroughouttheturndownrange.VFD’sarealsousedforfinalsystembalancingandtoreducethe
airflowwhenbuildingrequirementsarereduced.Inthiscase,thefanandwheelwidthareselectedusingthe
finaldesignCFMandstaticpressure.
Sound Power versus Sound Pressure
Thesoundvaluesdisplayedontheperformancepagesareintermsofinletsoundpower(L
Wi
A)andoutletsound
power(L
Wo
A).Thesevaluesaretheacousticpowerradiatingfromtheinletandoutletofthefan,respectively.
Soundpressure,expressedasdBA,istheacousticpressureatapointinspacewhichcanbemeasuredwitha
microphoneorcanbeheard.Toconvertsoundpower(L
w
A)intosoundpressure(dBA),thefollowingcorrections
areappliedforahemisphericalfreefield.
dBA=L
w
A-correction
DistancefromFan 3ft.(0.9m) 5ft.(1.5m) 10ft.(3.0m)
Correction 7db 11.5db 17.5db
Note:RefertoAMCAPublication303,ApplicationofSoundPowerLevelRatingsforadditionalinformationoncalculatingtypicalsoundpressurelevelsforfaninstallation.
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