Air compressor manufacturers have been touting their machine's specifications in advertising and marketing materials for decades. Terms like CFM, PSIG and dBA are commonly used. But what do they really mean and are they really a good indicator for measuring a compressor's performance? This article will explain the most common compressor specifications and arm you with the knowledge you need to make comparisons from model to model.
HP, or horsepower, is one of the most common specifications used by compressor manufacturers to rate their machines. However, horsepower should not be considered an accurate measure of the amount of air a compressor can make. As it applies to air compressors, horsepower ratings are based on the continuous power output of the compressor's electric motor shaft, or the continuous power input to the compressor shaft.
CFM/ACFM/SCFM, or cubic feet per minute, is the most important specification to consider when rating or comparing compressors. CFM is a measure of the amount of air a compressor can produce. All compressed air applications require a specific amount of CFM at a certain pressure to do their jobs properly. Obviously, a compressor that requires 5 HP to deliver 16 CFM is not as efficient as a 4 HP compressor that can produce the same amount of air. The difference is money wasted in electricity costs.
PSIG, or pounds per square inch gauge, is probably the most important specification after CFM. Psig is a unit of pressure relative to the surrounding atmosphere. Most hand-held pneumatic tools operate around 90 PSIG, with varying amounts of CFM required. Check your tool manufacturer's specifications prior to purchasing a compressor for your home or shop.
dBA or db(A), or decibel, is a measurement of the intensity or loudness of a sound. Although the loudness of an air compressor has no reflection on its performance, it should be considered if you plan on working close to your compressor. A compressor's operating dBA can be anywhere from 64 dBA to 130 dBA or more. Some compressors come with a sound reducing canopy for lower noise operation.
When comparing air compressor specifications, the key is to find the machine that produces the most CFM, using the least horsepower, at the lowest sound level (dBA) possible. Of course many other factors like price, quality and warranty should be considered when making an air compressor purchase, but understanding the key specs will help you feel more confident about your purchase.