Most compressors are not designed to run continuously. The capacity for this is usually expressed as the “duty cycle.” Duty cycle is the percentage of time the compressor can run in a 10-minute period without overheating. An average piston compressor may have a duty cycle of 50 to 60 percent, meaning it should not run more than five to six minutes out of a 10-minute period. Only compressors with a 100-percent duty cycle are made to run constantly.
-Ruth Dobbins, EtchMaster