The sequence issue with solenoid valves and pressure relief valves!
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For hydrogen pipelines, is it better to install the on/off solenoid valve in front of or behind the pressure regulator? What is the reason? The pressure relief valve has an inlet pressure of 35 MPa and an outlet pressure of 0.86 MPa
Following the process, it makes more sense to install it at the front. Since it is installed at the back, once the solenoid valve is turned off, the pressure behind the pressure regulator will gradually increase (pressure regulators generally leak; if they don’t leak, that’s another matter), until it reaches 35 MPa. If the solenoid valve is selected based on a value of 0.86, then the pressure will already be too high at this point. If selected based on 35, the pipe diameter after the pressure relief valve is larger than that before the valve, resulting in higher costs.
Theoretically, it should be placed after the pressure reducing filter, but in practice it depends on the operating pressure of the solenoid valve. Last week I built a differential pressure gauge fatigue tester; it stays in the open position, and no exhaust occurs when it closes. I checked the connections and the time relay, and they were all fine. Later, it turned out that the pressure after reduction was not high enough to activate the solenoid valve, so it had to be placed ahead