When the inlet/unloader valve is open, the air enters the compressor screw element. The screw element works like a pump and it compressed the air. During this process, oil is injected in the element. The oil is there to cool the air, as the air gets very hot during compression.
[pdf] Try to turn the compressor by hand. It should be possible to turn it around. It should turn around smoothly, without any 'hickups' (be sure to completely shut down the air compressor!). Check the isolation of the motor windings.
[pdf] A screw air compressor is very similar to a human heart. While a human heart has tricuspid, pulmonary, mitral, and aortic valves, a screw air compressor has four critical valves namely air inlet, minimum pres.
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