The principle of rotary screw air compression is really no different than reciprocating (piston) compression. Both are positive displacement machines that take in a fixed volume of air at atmospheric press.
[pdf] Screw air compressors are positive displacement compressors that rely on the rotation of intermeshing spiral rotors (male and female) to compress gas. Their key advantages include: High efficiency & reliability – Continuous, pulsation-free air supply with stable flow rates.
[pdf] They are powered by two counter-rotating screws that compress air as it moves through the compressor. These units are designed for continuous use, capable of operating 24 hours a day, 7 days a week.
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