Horsepower required to Compress Air
The horsepower required to adiabatic compression of air can be calculated with the calculator below:
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.
- 1 cfm (ft 3 /min) = 1.7 m 3 /h = 0.47 l/s = 28.3 l/min
- 1 psi (lb/in 2 ) = 6894.8 Pa (N/m 2 ) = 6.895 10 -2 bar
- 1 hp = 745.7 W
The power required for adiabatic (process without transfer of heat) compression of air can be expressed as
HP = [144 N P 1 V k / (33000 (k - 1))] [(P 2 / P 1 ) (k - 1)/(N k) - 1] (1)
where
HP = horsepower
N = number of compression stages
k = 1.41 = adiabatic expansion coefficient
P 1 = absolute initial atmospheric pressure (psi) (14.7 psi at sea level)
P 2 = absolute final pressure after compression (psi)
V = volume of air at atmospheric pressure - standard or free air (scfm, ft 3 /min)
- adiabatic compression (or expansion) takes place without transmission of heat
Related Topics
• Gases and Compressed Air
Air, LNG, LPG and other common gas properties, pipeline capacities, sizing of relief valves.
Related Documents
Compressed Air - Air Flow and Recommended Pipe Size
Pipe line sizing compressed air
Compressed Air Pipe Lines - Pressure Loss vs. Capacity and Operating Pressure
Pressure drop in compressed air pipe lines.
Compressed Air Piping - Pressure Loss Diagrams, Imperial Units
Pressure drop in compressed air pipelines with applied pressure 50, 100 and 150 psi.
Compressed Air Quality
Compressed air is used for power tools, instrumentation, processing, breathing and medical purposes.
Compressed Air vs. Free Air - Compression Ratio
The ratio of compressed air pressure to free air pressure.