[bachster]

Originally Posted by martin417

A quick exhaust valve is not covered by that rule, because it is not a pressure vent plug. A quick exhaust valve is a three port valve that passe air from one port to another port in one direction, but to an exhaust port in the other direction.

Sorry, I was referring to the 3-way valve that has a knob, Allen's third link. Since it only vents air from one direction, it seems there could potentially be an improper use where it would isolate a section from the vent plug which would then violate R89. Although maybe in order to get this you'd need to connect it "backwards" and it would then be venting all of the time, so it practice it couldn't really be used incorrectly. I'm just curious if anyone has found a useful application for these.

I agree that the quick exhaust valves are a nice way to vent a cylinder without needing to push air back through the solenoid.