Hydrogen gas. The flow through the valve could be in either direction, and must seal against the pressure differential in either direction when closed.
Leak rate on the order of .002cc/min.
I am looking for an electrically actuated diaphragm valve. I am picturing a direct acting, small orifice (Ø.032"), normally closed, 3000 PSI, solenoid driven valve. Is there such an animal?