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Engineering ToolBox > Horsepower required to Compress Air

Online horsepower calculator

The horsepower required to compressed air can be calculated with the calculator below:

N - number of stages

P₁ - absolute initial pressure (psi)

V - volume of compressed air at atmospheric pressure (cfm)

k - adiabatic expansion coefficient

P₂ - absolute final pressure (psi)

Theoretical horsepower required to compress one cubic foot of free air (atmospheric pressure) for single-staged, two-staged and three-staged compressors are indicated in the diagram below. In general - plus 15-20%  friction.

The power required to adiabatic compress of air can be expressed as

HP = [144 N P₁ V k / 33000 (k - 1)] [(P₂ / P₁)^{(k - 1)/N k} - 1] (1)

where

HP = horsepower

N = number of compression stages

k = 1.41 = adiabatic expansion coefficient

P₁ = absolute initial atmospheric pressure (psi) (14.1 psi at sea level)

P₂ = absolute final pressure after compression (psi)

V = volume of air at atmospheric pressure (cfm)

• adiabatic compression (or expansion) takes place without transmission of heat