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- May 16, 2016
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That is why unloader valves are fitted to most large and some small compressors, if setup correctly it will completely eliminates the problemthe Start capacitors on a compressor duty motor are substantially higher MFD and some also drop out the start winding at a higher RPM.
Both these items require a different start winding. The do deliver substantially higher torque on startup. conventional motors will start a empty compressor but will have trouble with one that is at operating pressure. The only piping that gets relieved by the pressure switch is the inlet pipe to the tank and about 5 strokes of the compressor has it to full pressure so the motor is truly starting under load.
Art B
Mostly it's only cheap compressors, "made to a price ", that don't use unloader valves.
A simple unloader valve can be fitted to any compressor by using a solenoid valve in the pipe from the compressor to the tank that opens on startup and remains open for a few seconds, whatever it takes to reach full speed. This valve dumps the air to atmosphere for a few seconds while the compressor runs up to full speed. Make sure you also have a non return valve at the tank inlet.