Ventilation fan cube law calculator

Under comparable centrifugal operation, power follows flow cubed.

Units

\mathrm{HP}_{\text{new}} = \mathrm{HP}_{\text{old}} \times \left(\frac{\mathrm{CFM}_{\text{new}}}{\mathrm{CFM}_{\text{old}}}\right)^{3}

Calculator

Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

Given

\mathrm{HP}_{\text{new}} = 32 \times \left(\frac{7600}{9500}\right)^{3} = 16.384

Symbol	Meaning	Unit
$\mathrm{HP}_{\text{new}}$	new centrifugal fan shaft power	HP
$\mathrm{HP}_{\text{old}}$	old centrifugal fan shaft power	HP
$\mathrm{CFM}_{\text{new}}$	new airflow	cfm
$\mathrm{CFM}_{\text{old}}$	old airflow	cfm

Symbol	Meaning	Unit
$P_{\text{new}}$	new centrifugal fan shaft power	kW
$P_{\text{old}}$	old centrifugal fan shaft power	kW
$Q_{\text{new}}$	new airflow	L/s
$Q_{\text{old}}$	old airflow	L/s

Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.