Hydraulic, Pneumatic & Fluid Power Systems worked example

Compressor Demand at 99% compressor isentropic and volumetric efficiency: a worked example

This scenario runs the compressor demand calculation on the strong side: 99% compressor isentropic and volumetric efficiency, with every other input held at its documented default. Use it when compressor demand in hydraulic, pneumatic and fluid power systems is being committed and you need a throughput number you can defend.

The inputs for this scenario

  • Total compressed air consumed (free air): 1,200 scf (unchanged)
  • Compressor runtime this period: 8 hr (unchanged)
  • Compressor isentropic/volumetric efficiency: 99 % (raised for this scenario; the documented default is 90)

Working through the calculation

  • Applying the documented formula (Raw compressor demand = completed output รท runtime) to the inputs above produces each figure below.
  • At this operating point the engine returns 149 units for effective throughput, the number this scenario is built around.
  • At this operating point the engine returns 150 units for raw throughput.
  • At this operating point the engine returns 99 % for efficiency.
  • At this operating point the engine returns 8 hr for runtime.

How this compares with the baseline

  • Against the tool's baseline example, where compressor isentropic and volumetric efficiency sits at 90% and the headline result is 135 units, this scenario comes in 10% above the baseline at 149 units.
  • Use it after metering a shift's air consumption to check whether your installed compressor capacity matches real demand. Treat this as a target state: the delta against the baseline quantifies what the improvement is worth before you commit to chasing it.

Results at a glance

  • Effective throughput: 149 units (headline result)
  • Raw throughput: 150 units
  • Efficiency: 99 %
  • Runtime: 8 hr

Run it with your numbers

  • Every input above is editable in the live Compressor Demand calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.