Model 921.16472 - Loss of tank pressure

by Riley
(San Diego)

I have a 33 gal, l.6HP, craftsman upright compressor, Model 921.16472. It is about 5 months old and has had very little use. From a tank pressure of 150 PSI, the pressure will go to nearly zero within 24 hours with the switch in the off position. I can't hear any air excaping. It does function properly and the compressor cycles on and off during use. Is it normal to lose air pressure in the off position?

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Riley, no, it's not normal for the tank pressure to drop to zero on its own, which means that you have a small leak in a fitting perhaps, or the tank check valve may not be seating perfectly.

On the other hand, it is recommended that you open the tank drain and bleed off all water from the tank after each use of the compressor. This generally means that the tank pressure is bled down to zero PSI anyway.

If you do that, the fact that it has a small leak is inconsequential, isn't it?

Use a few drops of liquid dish soap in water to test the fittings when there is air in the tank. If you don't see bubbles forming around the fittings, the leak isn't there. Put some of the soap solution over the unloader valve vent. If you see bubbles there, it is likely your check valve isn't seated completely. Remove clean and replace it, after you shut off the compressor and dumped all air from the tank.

Cheers,

Bill

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Apr 17, 2012
Regarding pressure loss.
by: Riley

Thanks, Bill. I'll follow your instructions.


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