Air velocity is calculated by dividing the volumetric flow rate by the cross-sectional area of the air flow passage. Air flow is usually provide by one or more fans. Although most fans are normally rated and compared at their free air delivery at zero back pressure, nearly all applications have flow resistance so the fans act against some back pressure. For axial fans the volumetric flow rate can be derated to about 60% to 80% of free air delivery to anticipate typical levels of backpressure.
Access the Aavid Flow Velocity Calculator, please click on the link below.