Fan brake horsepower (BHP) calculator

Match the fan pressure basis and efficiency; shaft horsepower is not electrical input power.

Units

\mathrm{BHP} = \frac{Q \times \mathit{dP} \times 100}{6356 \times \eta_{f}}

Calculator

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

Given

\mathrm{BHP} = \frac{18{,}000 \times 3.2 \times 100}{6356 \times 70} \approx 12.946

Symbol	Meaning	Unit
$\mathrm{BHP}$	fan shaft power	hp
$Q$	air volume flow	cfm
$\mathit{dP}$	fan pressure rise	in. w.g.
$\eta_{f}$	fan efficiency on the specified pressure basis	%

Symbol	Meaning	Unit
$P_{\text{shaft}}$	fan shaft power	kW
$Q$	air volume flow	L/s
$\mathit{dP}$	fan pressure rise	kPa
$\eta_{f}$	fan efficiency on the specified pressure basis	%

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