What it means
Specific power relates electrical input to delivered air flow. A lower figure at the same conditions means less energy for the same air. It depends on the machine type, its load, the pressure and the way flow and power are measured.
Compare on the same basis
A fair comparison needs:
- The same delivery pressure
- The same reference conditions for flow
- The same scope of power: motor, package or package plus auxiliaries
- The same load point, because efficiency changes with load
Machine versus system
A machine with good specific power can still sit in a poor system. Pressure drop, leakage, controls and treatment losses add to the energy used per unit of air reaching the process.
Use it carefully
Quoted figures should be read together with their test basis. We do not rely on a single figure from a brochure to judge a real installation. Measured power and flow on your site is the better evidence.
Starting data
To start, it helps to have:
- Compressor make, model, rated power and controls
- Operating pressure settings and the lowest pressure the processes need
- Operating hours and shift pattern
- Any existing power, flow or pressure records
Frequently asked questions
Is lower specific power always better?
At the same conditions, yes, but only if the figures are measured on the same basis, and the machine suits the load pattern.
Can I measure it on my own compressor?
With suitable power and flow measurement, yes. The method and conditions must be recorded.
Does a new compressor guarantee better specific power?
Not by itself. The result depends on how it is loaded and how the system is run.
Field guide
Specific power: the efficiency number that matters
Specific power is the electrical power a compressor uses for each unit of air it delivers, usually kW per m³/min or kW per 100 CFM, at a stated pressure. It lets you compare machines and spot a compressor that has lost efficiency.
How to measure it
- Measure input power at the panel with a power meter (not just motor current).
- Measure delivered air, ideally with a flow meter, or by a receiver pump-up test of known volume.
- Record the discharge pressure and conditions at the time.
- Divide power by flow, and compare with the manufacturer's data at the same pressure.
Why it drifts
- Blocked inlet filters and fouled coolers.
- Worn airend or valves delivering less air for the same power.
- Slipping belts.
- Pressure set higher than needed: higher pressure always means higher specific power.
Compare specific power only at the same pressure and on the same basis (package input power including fans and drives).
What to send for a quotation
- Compressor make, model and rated power of each machine.
- Electricity tariff and annual running hours.
- Typical pressure at the compressor and at the furthest user.
- Any measurements you already have (power, flow, loaded hours).
Send it through find my part or the spare parts enquiry, or call +91 99590 60718 or +91 92468 88812.