Rotary screw compressors use two meshed rotating positive-displacement helical screws to force the gas into a smaller space. However, it suffers from higher losses due to clearance volumes, resistance due to discharge and suction valves, weighs more, is difficult to maintain due to having a large number of moving parts, and it has inherent vibration. Because of this, it finds use in a wide range of applications in many different industries and can be designed to a wide range of capacities, by varying size, number of cylinders, and cylinder unloading. This type of compressor can compress a wide range of gases, including refrigerant, hydrogen, and natural gas. Household, home workshop, and smaller job site compressors are typically reciprocating compressors 1½ hp or less with an attached receiver tank.Ī linear compressor is a reciprocating compressor with the piston being the rotor of a linear motor. Īnother type of reciprocating compressor, usually employed in automotive cabin air conditioning systems, is the swash plate or wobble plate compressor, which uses pistons moved by a swash plate mounted on a shaft (see axial piston pump). In certain applications, such as air compression, multi-stage double-acting compressors are said to be the most efficient compressors available, and are typically larger, and more costly than comparable rotary units. Discharge pressures can range from low pressure to very high pressure (>18000 psi or 180 MPa). Larger reciprocating compressors well over 1,000 hp (750 kW) are commonly found in large industrial and petroleum applications. Small reciprocating compressors from 5 to 30 horsepower (hp) are commonly seen in automotive applications and are typically for intermittent duty. They can be either stationary or portable, can be single or multi-staged, and can be driven by electric motors or internal combustion engines. Reciprocating compressors use pistons driven by a crankshaft. Main article: Reciprocating compressor A motor-driven six-cylinder reciprocating compressor that can operate with two, four or six cylinders. The increase in the pressure of the gas is due, at least in part, to the compressor pumping it at a mass flow rate which cannot pass through the outlet at the lower pressure and density of the inlet. Put another way, a positive displacement compressor is one that operates by drawing in a discrete volume of gas from its inlet then forcing that gas to exit via the compressor's outlet. The main and important types of gas compressors are illustrated and discussed below:Ī positive displacement compressor is a system that compresses the air by the displacement of a mechanical linkage reducing the volume (since the reduction in volume due to a piston in thermodynamics is considered as positive displacement of the piston). Each stage further compresses the gas and increases its pressure and also temperature (if inter cooling between stages is not used). Often, the second stage is physically smaller than the primary stage, to accommodate the already compressed gas without reducing its pressure. Many compressors can be staged, that is, the fluid is compressed several times in steps or stages, to increase discharge pressure. The main action of a pump is to pressurize and transport liquids. Gases are compressible, while liquids are relatively incompressible, so compressors are rarely used for liquids. The main distinction is that the focus of a compressor is to change the density or volume of the fluid, which is mostly only achievable on gases. An air compressor is a specific type of gas compressor.Ĭompressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. A small stationary high pressure breathing air compressor for filling scuba cylinders High pressure reciprocating compressor from Belliss and Morcom, used in the bottling industryĪ compressor is a mechanical device that increases the pressure of a gas by reducing its volume. For other uses, see Compressor (disambiguation).

Electric air compressor