How does pressure relief valve work?

[badkarma]

I know the basics of it. What I don't know is does it completely drain the air out or does it drain down to the specify psi? Example: 100psi pressure relief valve when over filled will pop off to release pressure. Does it close up when it reaches back down below 100psi or does it completely drain out all the air out of the pressure chamber?

[pyromanic13]

mine close up below "pop" pressure

[Hotwired]

Its just a sprung poppet valve.

Pressure goes over its set limit, poppet valve cracks open and lets air out until pressure is within limits again.

It doesn't drain the chamber.

[badkarma]

Thanks!!!

[jrrdw]

The relief valve on my air compressor wont close back on it's own until it gets down to around 50psi. It pops open at around 130psi. It says 115psi on it, i guess that check balls and springs can't be intirely accurate.

[BC Pneumatics]

How old is the compressor? Perhaps the spring will fatigue down to 150psi with some use. (Or maybe it is just a cheapo valve... who knows!)

[jrrdw]

How old is the compressor? Perhaps the spring will fatigue down to 150psi with some use. (Or maybe it is just a cheapo valve... who knows!)

2 years old this spring. I've never seen the numbers jive with these things, wheather it be the guages a little off or the pop valves. They more commenly pop on the gas engine driven portable compressors then stationary one's. The engine vibration tends to set them off.

[spudthug]

my aircompressers *pop* thing broke one day....it got stuck then just like blew up....idk if that was the pop thing u guys were talking about but mines not there anymore