It should turn around smoothly, without any 'hickups' (be sure to completely shut down the air compressor!). Check the isolation of the motor windings. Should be in the mage-ohms (you need an isolation tester / high voltage ohm meter for this). Check the voltage when the compressor is running.
[pdf] With dozens of highly rated air compressors to choose from, it was a challenge to select the top performers for our hands-on tests. We considered brand names to an extent—after all, manufacturers such as Ca. While a reciprocating air compressor is quiet, a rotary screw air compressor is more silent. This air compressor has two separate helical screws working in unison to get the job done. Note that the two screws do not come in contact with each other, making them quieter.
[pdf] Displacement (m³/min): It refers to the volume of air discharged by the compressor per unit of time, also known as flow rate or volumetric flow rate. Discharge pressure (MPa): It indicates the pressure of the air at the compressor’s outlet, usually measured in megapascals (MPa).
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