Ratio of Free Air to Compressed Air

Compression Ratio - Discharge Pressure Absolute to Suction Pressure Absolute

Free air is air at ambient conditions at a specific location where 

  • ambient temperature
  • moisture content
  • barometric pressure

are stated.  

Compression Ratio

Compression Ratio is the ratio between Discharge Pressure Absolute and Suction Pressure Absolute.

The compression ratio of free air - to compressed air, is indicated in the diagram below.

Compression Ratio - Pressure (psi)

ratio of compression free air to compressed air - diagram in psi

  • 1 psi = 6.9 kPa = 0.069 bar
  • 1 ncfm = 0.5 nl/s

Example - Converting a Compressed Air Volume to a Free Air Volume

A compressed air volume flow of 10 acfm at 100 psig must be multiplied with a compression ratio approx. 8 to find the free air flow at atmospheric pressure.

  • in this case approx. 80 scfm

Compression Ratio - Pressure (bar)

ratio of compression free air to compressed air - diagram in bar

Related Topics

  • Piping Systems - Dimensions of pipes and tubes - dimensions, materials, capacities - pressure drop calculations and charts - insulation and heat loss diagrams

Related Documents

Tag Search

  • en: free air compressed compression pressure psi kpa

Search the Engineering ToolBox

- "Search is the most efficient way to navigate the Engineering ToolBox!"

Engineering ToolBox - SketchUp Extension - Online 3D modeling!

3D Engineering ToolBox Extension to SketchUp - add parametric components to your SketchUp model

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your SketchUp model with the Engineering ToolBox - SketchUp Extension/Plugin - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp from the Sketchup Extension Warehouse!

Translate the Engineering ToolBox!
About the Engineering ToolBox!

Support the ToolBox

If you find the Engineering ToolBox useful and want this website to be available tomorrow - and the days after tomorrow - enable ads or make a contribution!

Contribute to the Engineering ToolBox