Reasons for the metallic knocking sound in check valves
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On the gas outlet pipeline of the reciprocating hydrogen compressor, there was a DN150, PN25 cast-steel vertical lift check valve; it had been in use for two years without any knocking sounds. Recently, due to slight loosening of the bolts connecting the slide body to the crankcase, the bolts were tightened and the coaxiality of the coupling was adjusted. The compressor was started up to adjust the output pressure so that it could be connected to the grid, and at that point knocking sounds occurred as the valve core struck against the valve seat. What causes it, and how can it be eliminated?
Is it caused by low flow in the pipeline network?
I’m sorry, I didn’t explain clearly; a total of 3 units are in operation, and the other check valves don’t make any knocking sounds.