How To Calculate CFMs

A clogged or rusty fan will work far below calculated expectations.
••• Jupiterimages/Photos.com/Getty Images

Your fan's expected blow rate can be calculated from the amount of power it consumes and the pressure at which it works. The calculation will determine the fan's CFM value -- meaning how many cubic feet of air it displaces each minute. This value is essential to know when designing a ventilation system or an industrial exhaust system. If a fan fails to meet an area's ventilation or exhaust needs, you will need to select a different fan or install multiple units.

    Convert the fan's stated power rating from kilowatts to horsepower by multiplying by 1.34. If the fan works, for instance, at 6 kW, then 6 x 1.34 = 8.04.

    Convert the fan's rated pressure, which manufacturer documentation specifies, from pounds per square inch to feet of water by dividing by 0.433. If the fan works, for instance, producing 0.1 psi: 0.1 / 0.433 = 0.23 feet of water.

    Divide the horsepower by the fan's pressure: 8.04 / 0.23 = 34.96.

    Multiply the result by 530, a conversion constant: 34.96 x 530 = 18,528.8, or approximately 18,500. This is the number of cubic feet of air the fan should displace each minute.

Related Articles

How to Calculate Fan Output
How to Calculate CFM Output
How to Figure GPM Water Flow on an Existing Chiller
Can You Use a Pressure Washer With a Rain Barrel?
The Different Parts of a Generator
How to Convert HVAC Tons to Amps
What Is a Centrifugal Blower?
How to Convert BTU to KW
How to Convert KBTU to BTU
How to Convert GPM to HP
How to Calculate PSI
How to Calculate the Horsepower of a Compressor
How to Convert HP to BTU/hr
How to Calculate Tons of Cooling for a Cooling Tower
How to Calculate Duct Airflow
How to Calculate the Minimum Flow Rate of the Cooling...
How to Calculate Water Wheel Power
How to Convert KPS to PSI
How to Convert Horsepower to kWh
How to Go From CM to MMHG

Dont Go!

We Have More Great Sciencing Articles!