An air compressor datasheet is full of figures that can mislead a buyer who does not know which ones matter. Free air delivery, specific power, discharge pressure and duty cycle are the numbers that determine whether the machine will actually do the job.
Key figures explained
- Free air delivery (FAD) — the air volume actually delivered, measured at inlet conditions
- Discharge pressure — the working pressure the machine sustains
- Specific power — kW per m³/min, the efficiency measure
- Duty cycle — how long the machine can run without overheating
- Noise level and dimensions for installation planning
Common pitfalls
Displacement is not the same as free air delivery; displacement is the theoretical swept volume and is always higher. Check the inlet conditions under which FAD is quoted, and compare specific power at the same pressure, not different pressures.
Using the datasheet
Match FAD to your measured demand at the working pressure, confirm the duty cycle suits continuous use, and compare specific power between machines. The datasheet should also state the ambient temperature limits and cooling requirements for your site.