An air compressor or a gas compressor operates on the simple principle of taking in a quantity of air or a certain gas and increasing its pressure many times over by reducing its volume. Compressors are similar to pumps as they both increase the pressure on a fluid and they can both transport the fluid through a pipe. Air compressors depend on several drive types and pump technologies. Common drive types are AC, DC, gas engines and diesel engines. Common pump types are positive displacement (piston, diaphragm, rotary vane and screw styles) and non positive displacement (centrifugal, axial and regenerative blowers).
Air compressors may have integral tanks for storing compressed air or discharge it directly to the output valve. Many types of compressors also generate vacuum conditions. Air compressors are used in a wide array of industrial applications such as refrigeration and deep sea diving as well as at service stations for filling tires. The technology is also used in pressurized aircraft cabins and in manufacturing environments to store gases.
There is a wide variety of air compressors that are used for industrial applications. Some of the more common ones are: reciprocating compressors, rotary screw compressors, centrifugal compressors and axial-flow compressors. Most compressors are equipped with cooling fans as compressing gases generate quite a bit of heat. The compressor flywheel may drive the cooling fans. The compressed air is to be cooled between stages making the compression less adiabatic and more isothermal. The inter-stage coolers cause condensation so that means water separators with drain valves need to be present so you can drain the water.
Air compressors that are sold to and used by the general public are often attached on the top of a tank that is used for holding the pressurized air. Oil-lubricated and oil-free compressors are also available.
Compressors can be powered by motors, but the type of motor used depends upon the application it is used for. For large air compressors, steam turbines are used whereas for domestic purposes, electric motors are generally used. Compressors are normally made from steel and other metal alloys in order to withstand the tremendous pressure that the gases can exert.