* Face velocity: Measures the speed of air moving through an opening (like a fan or air filter) in feet per minute (fpm). It's essentially the air speed at the face of the opening.
* Cubic feet per minute (cfm): Represents the volume of air moving through an opening per minute. It's a measure of airflow rate.
To calculate cfm, you need both face velocity and the area of the opening:
cfm = Face Velocity (fpm) x Area of the Opening (square feet)
Example:
* Face velocity: 1000 fpm
* Area of the opening: 2 square feet
* cfm = 1000 fpm x 2 sq ft = 2000 cfm
Important Note: This formula assumes uniform airflow through the opening. In reality, airflow can be uneven, especially with complex openings or high velocities.
