Fan Law Calculator

The Fan Law Calculator App has been designed to allow quick estimation of the performance impact of variation in airflow and/or rpm on an existing system. The standard fan law equations are used to estimate the system performance changes.

Input the current values for airflow, rpm, pressure and current (or power) into the appropriate text field. The calculations will automatically update as you type.

The updated values can be input in one of two ways. The new values can be entered into the appropriate text field. Or, you can drag the airflow value left and right on the graph view to change the values. The calculations will automatically update as you edit the values.

Calculations

The standard fan law equations are applied:
cfm2 = cfm1 * rpm2/rpm1
sp2 = sp1 * (cfm2/cfm1)^2
power2 = power1 * (cfm2/cfm1)^3

Notes:
This application (App) is provided for use by qualified HVAC engineers and designers in the design of air handling systems and is not a substitute for appropriate design services. When in doubt, contact a design