Duty cycle

Duty cycle is the fraction of any given time window during which a compressor is rated to run under load. It is reported as a percentage (50 percent, 75 percent, 100 percent / continuous). The number tells you how hard you can work the machine before exceeding its thermal and mechanical design envelope.

What it is

Small piston compressors are typically rated 50 percent to 75 percent. They run, build pressure, then must rest for an equal or longer period to dissipate heat from cylinders, valves, and the motor. Rotary screw and most industrial reciprocating compressors are rated 100 percent / continuous: they are designed to run loaded indefinitely at rated conditions. Cooling system, lubrication, and motor frame are all sized to support that.

Why it matters

A 50 percent duty cycle compressor sized for 20 SCFM only delivers 10 SCFM in steady demand. Buyers who skip the duty-cycle line on the data sheet routinely buy a compressor that meets their peak number but cannot sustain it for a full shift. The result is a hot machine, accelerated valve wear, and shortened life. For any demand that runs more than a few minutes per hour, continuous-duty machines are the only safe choice.

How it is used in our catalog

Industrial machines in our catalog are 100 percent continuous duty. Light-duty piston units explicitly list 50/75 percent ratings and an applicable on-time per hour. Compare rotary screw (continuous) against industrial reciprocating (continuous) and lower-duty homeowner-grade alternatives.

Common questions

Does duty cycle apply to rotary screw compressors?

Standard industrial rotary screws are continuous duty. The relevant analogue is load/unload cycle frequency, not duty-cycle percentage.

What happens if I exceed it?

Cylinder head temperatures climb, oil thins, valves carbonize, and the motor’s service factor is consumed early. Continuous overload can void warranty.