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Plant Engineering Calculator

Updated Sep 18, 2026

Compressed Air System Efficiency Calculator — Useful Air Power vs Electrical kW

Estimate simple pressure-flow power at point of use from free-air flow and pressure, compare it with measured electrical input and report a transparent system-efficiency indicator.

Live calculationWorking shownPrivate in browser

Inputs

Results

Line flow 1.26 m³/min
Pressure-flow power 14.75 kW
Screening efficiency 19.7%
Specific power 7.50 kW/(m³/min)
More actions

Shared links reopen these inputs. Recent and saved calculations stay in this browser unless you clear site data.

Formula

Qline=Qfree×Patm/Pabs; Ppressure≈pgauge×Qline; ηscreen=Ppressure/Pelectric.

Your calculation, step by step

These steps use the values currently entered above so the result can be checked independently.

  1. 1.Absolute line pressure = 7.000 + 1.013 = 8.0130 bar abs.
  2. 2.Line-condition volume = 10.000 × 1.013 ÷ 8.0130 = 1.26420 m³/min.
  3. 3.Simple pressure-flow power = 7.000 bar × 10⁵ Pa/bar × (1.26420 ÷ 60) m³/s ÷ 1000 = 14.7489 kW.
  4. 4.Screening indicator = 14.7489 ÷ 75.000 × 100 = 19.665%; specific power = 7.5000 kW/(m³/min free air).

How to use this calculator

  1. Enter measured or design values using the units shown beside each field.
  2. Review the live results and the substituted calculation steps before using the estimate.
  3. Check the assumptions below, then continue to a related calculator when the next engineering decision needs another model.

Worked example

The result makes the large conversion gap between electrical input and useful pressure-flow power visible without presenting it as compressor exergy efficiency.

Assumptions and limits

  • Uses a simple pressure-volume power screen, not reversible isothermal/exergy efficiency.
  • Flow and pressure must be measured at a consistent system boundary.

How to interpret the result

Treat the primary result as an engineering screening value, then use the secondary outputs to understand scale, energy or operating impact. Confirm site measurements, equipment limits and applicable standards before making a design or control change.

Questions engineers ask

What does “pressure-flow power” mean here?

It is the simple p·Qactual mechanical power rate associated with line pressure and actual volumetric flow. It is a transparent screening indicator, not the reversible isothermal compression/exergy efficiency of the compressor.

Why convert free-air flow to line flow first?

The actual volumetric flow inside the pressurized system is lower than its free-air equivalent. The owner scales by absolute pressure before calculating p·Q at the point-of-use boundary.

How should this efficiency be used?

Use it as a consistent trend/comparison indicator when flow, pressure and electrical input are measured at matching boundaries. For compressor thermodynamic efficiency, use a model based on compression work, inlet conditions and stages.

Continue the calculation

Use the next calculator in the same engineering workflow instead of restarting from search.

compressor specific powercompressed air pressure dropcompressed air demand profile
Methodology. MAXScanner shows the governing formula, entered values and calculation outputs so the estimate is auditable. The calculator is a screening aid; assumptions and equipment-specific limits remain part of the engineering review.