A valve that functions in a manner that is opposite of a relief valve: a valve that closes when pressure gets above a setpoint.
The application is at the outlet of an air cylinder that is to slow movement of an arm if the actuator lifting the arm fails.  The outlet of the air cylinder is ported through two parallel openings, a small orifice and a larger opening.  If the load is "dropped", I want the larger opening to close so that the air cylinder drops slowly.
Another possibility: a check valve that allows a certain amount of low pressure leakage before it is forced shut.Really the same problem frame around velocity instead of pressure.The smallest one is still a bit large, though, and may not respond fast enough.Maybe if I use a larger cylinder.The current plan is for a pressure switch and a solenoid valve.  That is preferred, because then the switch can also signal to shut off the test fixture.
I still need to spar with the old school guys who want something 100% mechanical.  At least this is getting me out to learn a few new things.
I can almost picture a device that could work, like a swing check or diaphragm valve with a spring to counter light pressure.  Not actually finding such an animal.

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