Reciprocating compressors are best for intermittent applications, meaning the demands aren’t constant. Fill a tire, run the lift, bead blast a couple parts. These compressors are meant for, at most, a 50% duty cycle, meaning it should run for a few minutes, then be off for a few minutes. Some manufacturers will say a 100% duty cycle, and it will…until it burns up. If your recip compressor is running more than it’s not running, it’s undersized and won’t last.
Once you start running grinders, sanders, serious media blasting or paint guns a lot of the time, upgrading to a screw compressor is a good option. They are meant to run continuously. On the converse side, if your screw compressor is over-sized, it can be just as bad. Frequent short cycling is bad for the components. On any compressor with an oil sump, if it doesn’t run enough to get heated up, water can build up in the oil and cause problems. Relieve the pressure when you’re done using it and always check the oil before you start it up. Some suppliers make screw compressors down as low as 5 hp, but 15 hp is the usual starting point. The very small models get so compact and are so “valueengineered” to keep costs down that their reliability suffers severely.
Most auto garages run a 5–10 hp reciprocating compressor with a 120 gallon tank and a dryer. This size can keep up with a few garage bays, with techs running air tools as needed. For a home mechanic working on the weekends, a 3 hp compressor on a 30–60 gallon tank will keep you happy for years. Just make sure to keep the tank drained and check the oil every time you use it.
If you have the space, don’t skimp on the receiver tank. Receiver tanks help keep the stops and starts down. The bigger the tank, the better. It’s basically a shock absorber for the system. Tanks are generally the cheapest, lowest maintenance item in a compressed air system, but, unfortunately, the most under-purchased. A bigger tank can let you do four minutes of bead blasting instead of two before the pressure drops too low and you have to wait until the tank is refilled.