Screw Compressor: Working Principle of Screw Air Compressor

(Last Updated On: 02/09/2017)
Do you have screw compressor? Are you interested to know the working principle of screw air compressor?
Here I will share details with you because every engineering plant requires compressed air to perform various operations.
This compressed air can be obtained by screw compressor. The most useful and important air compressor, are those, who give you trouble-free operation during working conditions.
To avoid various faults occurs during working of air compressor, you must know the working principle of the machine.
A reciprocating air compressor is easy to understand than screw air compressor.
working principle of screw compressor
  • Some Details About Screw Compressor

As the name indicates, this type of compressor is driven by electric motor or diesel engine.
The rotary screw air compressor is a single stage, oil flooded, and rotary screw compressor driven by electric motor through a coupling.
Now two stages, oil free air compressor is also available in the market. Teflon screws are used in such type of machines.
The compressors which are run by diesel engine are also known as a portable air compressor.
  • Construction and Working of Screw Compressor

The compressor casing accommodates a pair of male and female helical rotors. These will be machined with the highest precision and mounted on rolling element bearings.
A pair of ball bearings and roller bearings is used in drive and non-drive side.
The male rotor has four helical lobes which mesh with six flutes of the female rotor. The speed of the male rotor is 1.5 times higher than the female rotor.
The male rotor is driven by coupling through step-up gears. The male rotor lobes rotate into the female rotor flutes.
The air which is sucked through suction filter element trapped in the inner lobe spaces. So, it will smoothly compress until the lobe-flutes reach the outlet port.
Pulsation free air is delivered by screw air compressor, due to continuous compression takes place in all the lobe-flute spaces.
The oil injected through the lower gusset of the air compressor casing mixes with the indrawn air. It ensures an efficient sealing between the rotors and the casing.
This will also give an intensive cooling during the compression process.
A Huge quantity of lubrication oil cools the compressed air; therefore intercoolers are not necessary for screw air compressor.
The oil, which lubricates the compressor, seals the clearance spaces. In air cooled models, the oil is cooled in oil cooler by the separate fan motor. Whereas it is cooled by water, in water cooled models.
I hope the information above will help you understand the working of a screw compressor. To control various operation performed during working, many control valves are used. As like a minimum pressure valve, oil check valve, safety valve, intake/butterfly valve.

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