泵浦若因堵塞或管路上的阀类未开启等因素，会造成压力升高。当这个异常压力达到隔膜式释压阀所设定的压力时，液体会由此2.jpg阀回流，以达到保护泵浦及管路的目的。

It is to protect pumps from inadmissible excessive pressure.If the liquid reaches the preload pressure of the relief valve,the liquid flows through it to prevent pumps and pipes from damaged.