looking for a air valve that will release air when air pressure is releaced. smaller the better, for compressed air. carl.

Are you referring to a pop off valve?

Or pressure switch?

pressure relief valve?

Possibly a regulator? or maybe just a regular pop valve or ball valve.

what are you trying to do?

Trying to make a pvc cylinder i can get cylinder to work except when air is stopped it leaves the cylinder charged and want let cylinder release.air will leave over 2 hours, can't use it that way. carl.

www.industrialspec.com
BVS-2 is a bleeder valve that vents to atmosphere when depressed, it has a 1/8 male npt thread.

one place to check would be a heavy truck parts dealer, I used to drive spotter truck a while back and the 5th wheel king pin release is air operated. in witch you push and hold the button the cylinder engages and when you take your hand off the button the air releases from the button to the cylinder.