The piston compressor is one of the very first compressor models, but it remains the most versatile and always offers excellent performance. This type of compressor pushes a piston in a cylinder by means of a connecting rod and a crankshaft. If only one side of the piston is used for compression, the compressor is called a single-acting compressor. If both sides of the piston (upper and lower) are used, then the compressor is a double-acting compressor.
The versatility of piston compressors knows virtually no limit. They compress air as well as gas with very slight alterations. The piston compressor is the only model capable of compressing air and gas at high pressures; for breathable air applications for example.
The configuration of a piston compressor can be single-cylinder for low pressures / low volumes or multi-stages to compress a fluid at very high pressures. In this type of compressor, the air is compressed in stages, its pressure increasing bearing after bearing until becoming very high.
Typical applications:
Gas compression (CNG, nitrogen, inert gas, buried gas), high pressure (SCUBA SCBA cylinders, surface seismic, blowing air), P.E.T bottling, engine start, industry
Rotary screw compressor
The screw compressor is a volumetric compressor whose pistons are in the form of screws. This is the most used compressor model nowadays. The main parts of the screw compression element comprise a male rotor and a female rotor which rotate towards each other while the volume between them and the compressor housing decreases. The pressure ratio of a screw depends on the length and profile of the screw on the one hand, and the shape of the discharge port, on the other hand.
The screw compression element is not equipped with any valve and there is no mechanical force capable of creating any imbalance. It can therefore operate at a high shaft speed and combine a large flow rate and small external dimensions. You can read about portable compressors at https://www.chcompressors.com/portable-air-compressor/.
Compression capabilities:
The range of Gardner Denver rotary screw compressors operate at between 4 kw and 373 kW (5 and 500 hp) for a nominal pressure of 5 to 12 bar.