How do I calculate the CFM (cubic feet per minute) of an industrial fan?

Measure the Airflow Velocity: Use an anemometer or airflow meter to measure the velocity of the air being moved by the fan. Place the instrument at a distance from the fan where the air is relatively stable and not affected by other factors.

Determine the CrossSectional Area: Measure the crosssectional area of the opening or duct through which the air is passing. If the opening is circular, you can use the formula A = πr², where A is the area and r is the radius of the opening. If the opening is rectangular or irregularly shaped, measure the length (L) and width (W) and use the formula A = L x W to calculate the area.

Calculate the CFM: Multiply the airflow velocity (V) by the crosssectional area (A) to calculate the CFM. The formula is CFM = V x A.
It's important to ensure that the units used in the calculations are consistent. For example, if the velocity is measured in feet per minute (fpm) and the area is measured in square feet (ft²), the resulting CFM will be in cubic feet per minute (ft³/min).