I've been doing web searches for quite some time trying to find a solenoid valve capable of sealing off liquid flow even if a large differential pressure exists between the outlet and the inlet or vice versa. In other words, the valve should remain tightly closed in both of the following situations:1) 100 psig on the inlet, 0 psig on the outlet2) 0 psig on the inlet, 100 psig on the outletMost solenoid valves I'm aware of will open if outlet pressure greatly exceeds inlet pressure. Furthermore, I need a valve with a Cv of 1.5 or greater to keep my pressure drop in a reasonable range. I have yet to find a valve that meets all these criteria (on, and material compatibility with DI water and glycerin). I've used keywords like "bi-directional" but I'm not sure if that's what I want or not.What is the common name for a valve with these characteristics? Use a small solenoid valve on low-pressure instrument air to pilot the actuator on the ball valve.You might look at Maxon for solenoid valves with more horse-power. Unless there is something special, I would go with the actuated ball valveYour problem is with trying to find a large Cv direct-operated solenoid valve which will resist the differential pressure you need. Everything with a large enough Cv and max pressure for your needs is pilot operated. They rely on pressure differential between the upstream and downstream ports to actuate and to seal, or they require a low-pressure vent or return (eg. a spool valve). Hence the problem with bi-directional sealing. There's only so much force you can get out of an 8-watt or 12-watt solenoid coil!

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