Types of compressors: screw, reciprocating and centrifugal
Compressors split into positive-displacement and dynamic machines, and within those into reciprocating, screw and centrifugal. The type of machine determines both the wear pattern and the repair logic. We break down the three main families in plain terms: how they work, where they're used and what tends to fail first in each.
Positive-displacement and dynamic — the basic split
By compression principle, compressors fall into two large groups. Positive-displacement machines (reciprocating and screw) reduce the volume of gas in a closed chamber. Dynamic machines (centrifugal and axial) accelerate the gas with an impeller and convert flow velocity into pressure. This division drives almost everything else — from behaviour at part-load to which components wear first.
Reciprocating compressor
Compression takes place in a cylinder through the back-and-forth motion of a piston, with suction and discharge valves controlling the flow. Its strengths are high pressure and flexibility across operating modes, which is why reciprocating machines are common in oil and gas and at booster stations. The first parts to wear are the piston rings, valves, bearings and seals. A characteristic symptom of trouble is a rhythmic knock when clearances grow.
Screw compressor
Gas is compressed between two rotors; machines come in oil-flooded and oil-free (dry) types. The advantages are continuous, pulsation-free delivery and lower vibration, hence their use in instrument-air systems and on process gases. Service life is set by the rotor bearings, seals and the clearances of the rotor pair — and, in oil-flooded machines, by the condition of the oil separator.
Centrifugal compressor
An impeller accelerates the gas, delivering high flow rates at medium and high pressures. Such machines are installed on large process lines and gas-pumping units. Here the critical items are the bearings (often journal bearings), labyrinth and oil seals and rotor balancing, and the specific dangerous regime is surge.
The compressor type sets the repair strategy. On reciprocating machines you replace the cylinder-piston group and valves; on screw machines you recondition the rotor pair and bearings; on centrifugal machines you balance the rotor and restore the seals.
So the engineer's first question is what compressor you have and which manufacturer. That determines both the spare-parts set and the diagnostic method.
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