by Ram
(Goa, India)

We have a Quincy QR 310 air compressor with our liquid nitrogen plant. Quincy Air compressor unit is supposed to maintain 90 – 130 PSI pressure in air tank. So when pressure is 130 PSI, compressor motor stops and when pressure is 90 PSI motor automatically starts. It was working fine for last three years.

Quincy 310 Air Compressor
Quincy 310 Air Compressor

But now as soon as compressor motor stops (after achieving pressure of 130 PSI), air flows out from top (from unloader tower) see the attached photo.

I checked for diaphragm in unloader assembly, it looks fine no cracks. What can be wrong? It leaks air when the motor is off, no leak when motor is running.


Quincy 310 Air Compressor unloader leaks
by: Bill

The Quincy 310 is the pump. Assuming you have this pump attached to a tank, here’s a good place to start, Ram.

Though this page refers to a pressure switch leaking, the cause of that, and the likely reason for your Quincy unloader leaking are, I think, the same. I’m pretty sure it’s a check valve.

Have a look at the page, and add a comment if there’s still a problem.

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