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...

Ron, hello. Does your compressor run? Does it get up to cut out pressure and stop? When the pressure in the tank drops to cut in pressure, does the compressor start?

If yes to all of these, don't worry about the copper tube.

If, on the other hand, it is the unloader valve vent as you think, also don't worry. The check valve that prevents the tank air from bleeding out the unloader valve when the compressor has stopped is located where the air line enters the tank... at least normally.

Cheers,

Bill