丹富斯DFH42Y、DFH42W 型升降立式止回阀正常处于关闭状态，由于管线中进口端介质的压力作用，而克服弹簧阻力使阀门开启。当进口端介质压力低于出口端时，弹簧将阀芯推向阀座而使阀门关闭，阻止介质逆流，故起止回作用。

Dan fuss DFH42Y, DFH42W type vertical lifting check valve normally closed, due to the pressure of the inlet medium in the pipeline, and to overcome the spring resistance makes the valve opens. When the inlet pressure of medium below the outlet, the spring into the valve core seat and make the valve closed, stop medium counter-current, start-stop function back.