An air compressor is anything that increases the amount of air that is contained within a particular space. By packing in the air, the air pressure is increased. This creates a force that is useful for a variety of purposes, such as industrial, manufacturing, commercial and personal purposes.
One type of air compressor is the lung. When a person takes a deep breath to blow out a candle, for example, he or she is increasing the air pressure in the lungs, which effectively become air compressors containing pressurized air. The force of the air in the lungs is used to blow out the candle's flame.
Man-made air compressors generally fall into one of two types, either positive displacement or dynamic, and are defined by their mode of operation. A positive displacement air compressor works by filling and then emptying an air chamber. Three common types of positive displacement air compressors are reciprocating, rotary screw and rotary sliding vane air compressors.
Dynamic air compressors, on the other hand, use a rotating device to accelerate and then decelerate air. This process uses the speed or velocity of the air to increase the air's pressure. Centrifugal air compressors are dynamic air compressors.
Compressed air can be used in a variety of ways. It can be used to alter chemical composition, as in the case of making fertilizer; it can be used for industrial purposes, such as production line manufacturing processes; or it can be used to maintain industrial plants. Perhaps the most well-known use of air compressors is in the case of pneumatic tools such as air-powered nail guns, staplers, sanders, spray guns and ratchet wrenches. Air compressors also can be used to move debris.
Another way to group air compressors is by the number of stages they have. A two-stage air compressor usually is used for heavy-duty use and offers a higher level of compression than smaller, single-stage air compressors. Two-stage air compressors can store air for future use and are more energy efficient because they produce more air per unit of horsepower than single-stage compressors. Also, less heat is generated in a two-stage compressor, which means that wear on the unit is reduced. Portable electric air compressors also are available for light-duty applications.
There are hand-powered air compressors, but most are powered by either electricity or natural gas. Natural gas air compressors usually are more cost effective. If the air compressor is used in a small, enclosed area, however, an electric model might be more desirable in order to avoid gas fumes. Depending on the type of air compressor, operation costs can be high, as in the case of plant maintenance.