Compressor Parts Key Terms

Know compressor parts key terms to purchase and maintain your air compressor

By Steven A. Ottem

Knowing the key terms of air compressors will help you select the right air compressor and enable you to keep it running safely and efficiently. Sizing and locating your compressor correctly with an eye for maintenance costs will pay off in the long run.

Air compressors take up space whether stationary or portable. They generate heat and noise, so you will want to plan carefully where to locate or store your air compressor. Factors to consider include whether noise will matter, where to locate air outlets, as well as the size and type of compressor.

Rotary compressor

There are two types of rotary compressors. The rotary screw compressor operates at a lower noise level, generates less heat, and can run continuously without damage. It compresses air by using two screws or impellers that turn to compress air. A rotary vane compressor uses a rotor turning inside a cylinder to compress air.
Try: You can find an explanation of both types of rotary compressors at CompAir, along with moving illustrations to help you understand how each type of compressor works.

Reciprocating compressor

The reciprocating or piston-type compressor functions like an internal combustion engine. It has a piston and valves, a crankshaft and connecting rod. The piston compresses air as it moves towards the closed end of the cylinder.
Try: Pressure Products Industries illustrates the principle of a piston compressor. It includes several other compressor parts such as crankshaft, valves and connecting rods.

Dryers

Compressing air causes moisture to condense and collect in tanks and lines. Moisture kills air-powered equipment, so you must take steps to remove it from the compressed air system. You have a choice of refrigerated or desiccant dryers to remove moisture.
Try: ECompressedair lists both types of dryers and gives specifications for the machines it carries. ISC Sales provides an explanation of how desiccated dryers work.

Drive

Some air compressors use a belt between an engine and the compressor to run the compressor. Others may have the motor connected directly to the compressor. You will see "direct drive" or "belt drive" in the ads and parts lists.
Try: Northern Tool + Equipment pictures two belt driven compressors, as well as discussing aspects of buying and using an air compressor.

Control unit

All compressors must have a method of stopping the compressor when the pressure reaches a certain level. This is both for safety and to accommodate tools that operate within a certain pressure range. The control unit should restart the compressor when the pressure falls to a certain level.
Try: To see a typical control unit, go to Every Air Compressor.

Fittings

Air tools connect to an air compressor by pipes, hoses and a variety of connectors. Terms like quick couplers, chucks and nipples refer to the fittings that you can use to connect to the compressed air supply.
Try: Dino-Power Industry & Trade Co catalogs a variety of fittings with an international flair, showing couplers for air systems from many countries. Aubuchon Hardware displays air hose fittings such as couplers, connectors, nipples and chucks.