Duty cycle is the percentage of time a compressor can run in a given period without overheating. Piston machines are often rated at 50–75% duty, meaning they must rest between cycles, while rotary screw machines are typically rated for 100% duty, or continuous operation.
How to calculate it
Duty cycle is the running time divided by the total cycle time, expressed as a percentage. If a compressor runs for six minutes and rests for four, its duty cycle is 60%. Exceeding the rating overheats the machine and shortens its life.
Choosing by duty cycle
- Occasional tool use — 50% duty piston machine is enough
- Several hours per day — a higher-duty piston or small screw
- Continuous production — a 100% duty rotary screw compressor
Why it matters
Running a machine beyond its duty cycle is the most common cause of early piston compressor failure. If your demand is growing toward continuous use, moving to a screw machine is cheaper than repeatedly repairing an overworked piston unit.