300—26,000 CFM
10” TO 36” Dia Wheel
1/3rd To 25 HP
Utility (Vent) Set |
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300—26,000 CFM
10” TO 36” Dia Wheel
1/3rd To 25 HP
Restaurant Utility Set |
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300—26,000 CFM
10” TO 36” Dia Wheel
1/3rd To 25 HP
Utility (Vent) Sett |
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400-9000 CFM
9” TO 20” Dia Wheel
1/6th To 10 HP
Filtered Supply Fan |
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700-1600 CFM
7” TO 12” Dia Wheel
1/3rd to 3/4 HP
Double Inlet Direct Drive |
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300-12,000 CFM
7” TO 18” Dia Wheel
1/6th to 10 HP
Double Inlet Belt Drive |
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About Centrifugal Blowers:
Blowers are utilized when there is resistance to air flow, as might be caused by heating and cooling coils, filters,
ducting, and other things. Axial (propeller) type fans have limited ability to overcome such resistance.
The resistance is called “Static Pressure Loss” or “Static Pressure Drop, and is often abbreviated as “S.P”.
The units are normally inches of water column, “In, H2O”.
The blower must be set to the proper rpm , and have the corresponding HP, to overcome the sum of the individual
resistances in the air flow system.
The resistance data is often supplied by the manufacturer of the resisting component. For instance, filter
manufactures will set up an inclined manometer and measure the pressure drop across their filters in inches of
H2O. It is important to note that this will depend on air flow—when there is no air flow there is no pressure
drop at all. Therefore the data is often presented as a chart of pressure drop versus air velocity.
SP loss data for duct work and fittings is available from the ASHRAE Handbook of fundamentals chapter 32.
Ultimately the static pressure loss is always an estimate. Belt drive blowers often have a variable pitch pulley
on the motor which permits adjustment of blower rpm (hence CFM) by about 30%
Usage descriptions:
Backward inclined blowers are most commonly used when ducts are required to extract unwanted air or fumes. Suitable for modestly contaminated air. Common applications include:
Welding fume extraction or exhaust
General fume hood exhaust
Other various manufacturing processes
Grease laden cooking vapors
Bathroom area exhaust
Vapor removal from tanks or vessels
Ducted supply air
Replacing blowers?
The blower may have a label with informative data. If not, blowers are often matched based on:
.. Wheel blade style:
.. Forward Curved (FC). These have blades with a partial “C” shape , “squirrel cage”.
.. Backward Inclined (BI). Blades are flat, or nearly so, and have an inclined angle.
.. Wheel diameter , wheel width and shaft diameter.
.. Outlet dimensions
.. Number of inlets (Single or Double)
.. Old blower HP
.. Old blower RPM . If belt drive this can be determined based on the motor nameplate rpm x (motor pulley
diameter/ blower pulley diameter.)
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© 2010 Industrial Fans Direct
