Why is a safety valve installed at the inlet of the high-pressure hydrogen feed pump?

May I ask the original poster: is the safety valve installed in front of the inlet valve or behind it? If it is installed behind the inlet valve, I believe it is intended to prevent overpressure from damaging the equipment when the inlet valve is closed, by preventing leaks in the outlet valve and check valve.

It is basically to prevent pressure from flowing back into the inlet. The outlet pressure of a high-pressure pump is generally high, and the pressure rating of the pipes corresponding to it is also high; however, the pressure resistance rating of the pipes at the inlet side is usually not that high. A safety valve is installed to prevent the outlet pressure from backflowing to the inlet and causing accidents.

This is because pumps with safety valves as their inlet are those with a very large difference between inlet and outlet pressures (that is, the high-pressure pumps you mentioned). It can be said that the inlet of these pumps is connected to low-pressure equipment with relatively low pressure, while the outlet is connected to high-pressure equipment. Therefore, in the event of an emergency shutdown due to a pump failure, if the check valve at the pump’s outlet fails, it can lead to severe overpressure in the low-pressure equipment at the pump’s inlet. (I have also encountered situations where the low-pressure plate heat exchanger connected to the inlet of a high-pressure pump experienced overpressure.) A safety valve is installed at the pump inlet to release pressure urgently, allowing it to be discharged from the inlet as quickly as possible. Minimize overpressure on low-pressure equipment as much as possible. I’m not sure if you’ve noticed, but the setting pressure of the safety valve at the pump inlet is the same as that of the safety valve on the equipment connected to the pump inlet, and the reason for this is what I mentioned above.