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

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