Compressor manifold question

[avachava]

I am having to fabricate a new manifold for a shop compressor. The original Coleman Black Max had a poor design that I ordered parts for but could not fix. In re-plumbing the tank and fittings, I notice a very small, plastic line between the compressor output fitting and the pressure switch. What is the function of this feedback line and is it necessary? Thanks

 

[JustBob]

I am having to fabricate a new manifold for a shop compressor. The original Coleman Black Max had a poor design that I ordered parts for but could not fix. In re-plumbing the tank and fittings, I notice a very small, plastic line between the compressor output fitting and the pressure switch. What is the function of this feedback line and is it necessary? Thanks

That would be the unloader line, it is to relieve pressure between the tank and the pump when the compressor cycles off so that the pump and motor do not start under a load. You want to make sure and hook it back up so that it works properly, there will be a small amount of air escaping when the compressor cycles off. As long as the pressure switch and the check valve is working correctly you won't loose any of the air from the tank.