Properties of Fans

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BASIC FAN LAWS
Existing Flowrate (CFM):
Existing Static Pressure (in. H2O):
Existing Horsepower (HP):
Existing Speed (RPM):
New Speed (RPM):

New Flowrate (CFM):
New Static Pressure (in. H2O):
New Horsepower (HP):

FAN APPLICATION FORMULAS
Fan Brake Horsepower
Flowrate (CFM):
Static Pressure at Discharge (in. Water):
Static Fan Efficiency (%):

Brake Horsepower (HP):

Air Density
Barometric Pressure (in Hg):
Temperature (F)

Density (lb/Cu.ft.):

Velocity Pressure
Flowrate (CFM):
Cross Sectional Flow Area (sq. ft.)

Velocity Pressure (in. H2O)

Round Duct Equivelent of Rectangular Duct
First Side of Rectangular Duct (in.):
Second Side of Rectangular Duct (in.):

Round Duct Equivalent Diameter (in.)