Start with tool airflow at pressure
Pneumatic tools specify an airflow requirement at a working pressure, commonly CFM at 90 PSI. Compare that with the compressor's delivered CFM at the same pressure—not displacement CFM or a value measured at lower pressure. For tools used together, add simultaneous demand.
Continuous tools need sustained CFM
A nailer uses short bursts and lets the tank recover. A sander, grinder, spray gun or blast cabinet can consume air continuously. A large tank can delay pressure drop but cannot make up for a pump that produces less air than the tool consumes. For sustained work, pump output and duty cycle are the controlling numbers.
Tank size affects cycling and portability
More stored air reduces rapid cycling and provides a reserve for intermittent peaks. It also adds size and weight. Small portable tanks suit inflation and fastening; larger stationary tanks support longer intervals between pump starts. Choose gallons after determining required airflow.
Leave reasonable margin
Hoses, fittings, filters and regulators create pressure drop, and published tool consumption may represent an average. Select capacity above the calculated normal demand without treating maximum PSI as the performance score. Maximum tank pressure is not delivered airflow.
Sizing checklist
- List every tool's CFM at its working PSI.
- Add tools that operate simultaneously.
- Identify intermittent versus continuous use.
- Compare delivered CFM at the same pressure.
- Check pump duty cycle for the work pattern.
- Choose tank capacity for cycling and mobility.
Sources and further reading
- Compressed Air & Gas Institute resources
- Quincy Compressor resource library
- OSHA air receiver standard
Compressed air stores substantial energy. Inspect equipment, drain tanks, use rated components and never exceed the manufacturer's pressure limits.