The switch listed is a universal replacement pressure switch that replaces brands such as Furnas , Square-D and more.
The unloader equipped on this switch is used to unload the air pressure off the head of the compressor when the compressor shuts off,
this way when it starts there is no pressure on the piston and the compressor is able to start load free.
This valve usually has a 1/4" plastic or copper line that runs to the check valve or the head of the compressor.
If your compressor does not have an unloader line then this valve can be left not hooked up and the pressure switch will still function properly.
The preset pressure of this switch is most commonly used on two stage compressors
as long as the amperage is less than 20 amps on 120 volt or 12 amps on 240 volt.
This switch comes preset to turn the compressor on at 95 psi and shut off at 125 psi.
This can be adjusted to any pressure within the factory minimum and maximum set points listed below.
We have a picture showing the diagram for pressure adjustment.
-PRESET 95-125 PSI
-MINIMUM ON: 35 PSI
-MAXIMUM OFF PRESSURE: 150 PSI
-PRESSURE DIFFERENTIAL: 30-40 PSI
-¼" COMPRESSION UNLOADER VALVE CONNECTION
-¼" FEMALE NPT TANK CONNECTION.
-MAX AMPS, 20 AMPS AT 120VOLT / 12 AMP AT 240 VOLT