Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

# Horsepower required to Compress Air

## Calculate horsepower required by air compressors.

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 (ft3 /min) = 1.7 m3 /h = 0.47 l/s = 28.3 l/min
• 1 psi (lb/in2) = 6894.8 Pa (N/m2) =  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 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) (14.7 psi at sea level)

P2= absolute final pressure after compression (psi)

V = volume of air at atmospheric pressure - standard or free air (scfm, ft3 /min)

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

## Related Topics

• ### Gases and Compressed Air

Properties of air, LNG, LPG and other common gases. Pipeline capacities and 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.

## Search

Search is the most efficient way to navigate the Engineering ToolBox.

## Engineering ToolBox - SketchUp Extension - Online 3D modeling!

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with older versions of the amazing SketchUp Make and the newer "up to date" SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp Make/Pro from the Extension Warehouse !

We don't collect information from our users. More about

We use a third-party to provide monetization technologies for our site. You can review their privacy and cookie policy here.

You can change your privacy settings by clicking the following button: .

## Citation

• The Engineering ToolBox (2008). Horsepower required to Compress Air. [online] Available at: https://www.engineeringtoolbox.com/horsepower-compressed-air-d_1363.html [Accessed Day Month Year].

Modify the access date according your visit.

6.3.17

.