Even the smallest compressor can provide 60 and 90 PSI of pressure needed to run an air tool (check the tool’s manual for specific recommendations). However, most tools require a great volume of air to run at peak performance: Anywhere from 4 to 5 SCFM up to 15 to 20 SCFM or more. In contrast, a nail gun requires only about 2.2 SCFM to operate. Fortunately, you don’t need a compressor the size of a Volkswagen to run most air tools. SCFM ratings reflect the amount of air needed for a tool’s continuous operation. Even fairly small (2 to 3 HP) portable compressors can supply enough air to run all but the most air-hungry tools for short periods of time before the compressor must run to recharge its air tank. (One important caveat: letting any compressor run continuously can lead to overheating and premature wear.)
A good trick for getting more air volume from a smallish compressor is to hook up an auxiliary air tank between the compressor and the air tool.The tank creates a buffer of air, so the compressor doesn’t have to run as often to recharge. Alternately, if the job at hand doesn’t require the full-power output of the tool, you can reduce the tool’s SCFM needs by setting the compressor’s regulator to a lower air pressure than the tool’s recommended maximum.