According to air compressor principles, there are piston compressor, rotary compressors (turbine, water ring, turbine) compressors, axial compressors, jet compressors and screw compressors, etc. The most widely used are piston compressor.

How are piston compressors classified?

♦According to the cylinder position:

(1) Horizontal compressor

(2) Vertical compressor

(3) Angle compressors

♦According to the number of cylinder sections:

(1) Single-stage air compressor : the gas compressed one time in the cylinder

(2) Double-stage air compressor: the gas compressed twice in the cylinder

(3) Multi-stage air compressor: the gas compressed multiple times in the cylinder

♦According to the arrangement of the cylinders:

(1) Tandem compressor: same shaft with several cylinder

(2) Parallel compressor: everal cylinders in parallel on several shafts

(3) Duplex compressor: a multi-stage compressor composed of a series and a parallel type

(4) Symmetrical Balanced Compressor: The cylinders are arranged horizontally on both sides of the crankshaft where the crankshaft journals are 180 degrees from each other, and are arranged in an H-shape, and their inertial forces can basically be balanced. (Large compressors are all headed in this direction).

♦ According to the compression action of the piston:

(1) Single-acting compressor: the gas compressed on one side of the piston

(2) Double-acting compressor: gas can be compressed on both sides of the piston

(3) Multi-cylinder single-acting compressor: one side of the piston is used for compression

(4) Multi-cylinder double-acting compressors: compressors with multiple cylinders use both sides of the piston for compression.

♦According to the final exhaust pressure of the compressor:

(1) Low pressure air compressor: the final exhaust pressure is 3~10 gauge pressure

(2) Medium pressure compressor: the final exhaust pressure is 10~100 gauge pressure

(3) High-pressure air compressor: the final exhaust pressure is 100~1000 gauge pressure

(4) Ultra-high pressure air compressor: the exhaust end is above 1000 gauge pressure

♦According to the size of the compressor displacement:

(1) Micro compressor: below 1m³/min

(2) Small compressor:  below 1~10m³/min

(3) Medium-sized compressor: below 10m³~100m³/min

(4) Large compressor: 100m³

♦According to the speed:

(1) Low-speed compressor: below 2000 rpm

(2) Compressor with intermediate speed: at 200~450 rpm

(3) High-speed compressor: 450~1000 rpm

♦ According to the type of transmission:

(1) Electric compressors: those powered by electric motors

(2) Pneumatic compressors: those powered by steam engines

(3) Compressors powered by internal combustion engines

(4) Compressor powered by steam turbine

♦According to the cooling method:

(1) Water-cooled compressor: use the circulating flow of cooling water to conduct away the heat given in the compression process

(2) Air-cooled compressor: use its own wind power to conduct heat during the compression process through the heat sink

♦According to the transmission method:

(1) Install the rigid body coupling to directly drive the compressor or close to the compressor

(2) Direct drive compressor with flexible coupling

(3) Reduction gear drive compressor

(4) Belt (flat belt or V-belt) drive compressor

(5) Free piston compressor without crankshaft-connecting rod mechanism

(6) Compressor with positive structure – the motor cylinder of the motor compressor and the compressor seat are integrally made, and the compressor uses a common crankshaft

Whether air mixed with lubricating oil, air compressor can be divided into oil-type and oil-free type. Lubricating oil has the function of lubricating and cooling any mechanical equipment. It also has an air-tight effect to improve the volumetric efficiency. The effiency is definitely higher than oil-free. It is undeniable that the oil and gas will cause a lot of troubles in use. Even if it is processed by precision filters, it cannot achieve a safe and oil-free state. Although the energy efficiency of an oil-air compressor is higher, the cost of the precision filter are also considerable.