In calculating CFM from air velocity and area, which formula is used?

The formula used to calculate CFM (Cubic Feet per Minute) from air velocity and area is established through the relationship of air movement in a duct system. In this context, CFM represents the volume of air being moved per minute, while air velocity is measured in feet per minute (fpm), and area is the cross-sectional area through which the air flows in square feet (ft²).

When you multiply the air velocity (in fpm) by the area (in ft²), you effectively determine the amount of air passing through a given area in one minute. This is because the airflow can be visualized as moving a certain distance per minute (air velocity) through a specific space (area). Therefore, the correct relationship, which aligns with the principle of fluid dynamics, is that the product of velocity and area gives you the volumetric flow rate in cubic feet per minute (CFM).

Thus, the equation V(fpm) x Area(ft²) = CFM correctly captures this relationship and is essential for HVAC professionals to understand when measuring and controlling air flow in ventilation systems.