signal line

by Ron Kosmal
(Beaver Falls PA)

I recently purchased an ingersoll rand air compressor. 2stage, 5 hp, single phase. It seems in good shape, and wired correctly. Pneumatically, I have a reservation about the pressure shut off switch. It is mounted to the tank, and has a copper line coming out of it, and the guy that sold it to me said it was just a vent. I think that this is a signal line, and I do not know where to connect it to, or exactly what it does. Is it an unloader signal, and will I need a check valve somewhere if it is an unloader?


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Bill says..

Howdy Ron. Nice to hear from you.

The pressure switch has a line into itself from the tank (usually it's mounted on a pipe that connects right to the tank) allowing it to sense the pressure inside the tank.

When the pressure in the tank gets to the cut out pressure, that trips the mechanical switch, cutting off electricity to the motor.

At the same time, that also opens the unloader valve to allow air trapped over the piston to dump to atmosphere.

Your pressure switch needs a line into it from the tank, and some method of tripping the unloader valve open. If it doesn't, likely your air compressor will pop breakers when it tries to start again.

Maybe send in a photo so we can see what's what?

Cheers,

Bill