Guide to Air Compressors

Air compressors power all sorts of tools to lend mechanical advantage to the user. Whether the air is used to loosen seized fasteners or raise buildings, to use pneumatics and air power the air must go through a compressor first. Several important aspects determine a particular air compressor's suitability to a set of tasks or a range of tools.

Flow Capacity

The single most important rating for an air compressor is its flow capacity. Flow capacity is determined in cubic feet per minute or standard cubit feet per minute and is a measure of how much air the compressor can continuously put out at a given pressure. Common air tools require a certain CFM to operate without interruption, so it is crucial to choose a compressor whose CFM is at least higher than the highest tool it will have to power.

Tank Capacity

Tank capacity presents a trade off for users: the larger the tank, the longer it will take to fill before being able to use tools, but the longer it will last before having to refill. For sustained work, bigger is usually better, but for quick jobs a small tank will come up to pressure faster. Size is measured in gallons or liters and can be quite large, potentially making storage space and portability an issue as well.

Motor Power

Air compressors can be electrically driven or have gas, propane, or diesel engines to run the compressor motor. Higher horsepower ratings mean that the tank will fill up faster and can sustain its prressure longer, but will also consume more electricity or fuel. Gas and diesel compressors will work in remote locations without electricity, but for garage workshops the electric ones cost less, are quieter and don't produce exhaust.


Tank pressure in an air compressor is usually much higher than the pressure required to run air tools, so the regulator adjusts the outflow pressure. Regulators are user adjustable to allow the compressor to power a wide range of tools. Proper outflow pressure will ensure proper tool function and long life without unnecessary wear. If the pressure to the tool is too low it may not function, and if it's too high the tool may break.

Care and Maintenance

Air compressors require little care and maintenance. All compressor air tanks should be drained when not in use to allow condensation from the compression process to drip out. If this is not done, the condensation can begin oxidizing or rusting the inside of the tank. If the compressor's motor requires oil lubricant, the oil level should be kept full. A lack of lubrication will lead to premature wear and tear, and eventually motor failure.

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