Check valve venting during compressor filling.

by Marc

Eight gallon Kobalt compressor. Should Check valve be venting air while compressor is filling? It vents the entire time the compressor motor is running and then for about a minute after the compressor motor shuts off.

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Nov 30, 2016
Check valve venting
by: Bill

OK, Marc. Have a look at the Unloader Valve page on this site. That will explain what the little hole is doing.

You see, unloader valve cost money. A pressure switch that will trigger an unloader valve costs money.

Since your compressor has a mini-pressure switch (that's my name for it) there is no unloader valve as part of that switch.

How then, do you unload over the piston after the compressor stops, to ease the restart?

You bleed air out of the pumping process through that little hole all the time the compressor is running, then, when the compressor stops, the air in the tank is trapped by the tank check valve, air over the piston is vented out that hole until the pressure is gone, and the "leaking" stops.

It's not leaking, Marc. That's how it's designed to work. Instead of them paying for an unloader valve to work with the compressor (and raise the cost) you pay for the unloader by venting expensive compressed air all the time that the compressor is running.

Nov 30, 2016
Check valve venting
by: Marc

Bill,
Yes, it is a small pin hole in the middle of the flat surface on what the owners manual has listed as the check valve. That is where air is coming out of.
Marc.


Nov 30, 2016
Eight gallon Kobalt compressor venting
by: Bill

Marc, I couldn't see the check valve clearly on the image on found on line.

Is it a small hole in the check valve that is venting the air?

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