Specific energy is the key efficiency metric for compressed air. Calculating it from power and flow lets you compare machines fairly and track performance.
The Calculation
- Specific energy = input power (kW) ÷ free air delivery (m³/min).
- Measure power and flow under stable operating conditions.
- Record the working pressure, because it affects the result.
Example
- A 37 kW machine delivering 6.3 m³/min has specific energy of about 5.9 kW per m³/min.
- Lower values mean better efficiency.
- Compare machines at the same pressure.
Tracking Performance
- Recheck specific energy after maintenance.
- A rising value warns of wear or filter blockage.
- Use it to justify upgrades.
Does specific energy change with pressure?
Yes. Higher pressure needs more energy per cubic metre, so always compare at the same working pressure.
Talk to an Engineer
Contact Panrui with your flow, pressure and air quality requirements to get a recommendation and factory quote for your project.