Y42X type direct acting spring diaphragm pressure reducing valve belongs to the direct acting membrane spring pressure reducing valve. It is mainly composed of adjusting spring, diaphragm, piston, valve seat, valve disc and other parts. The diaphragm is used to directly sense the downstream pressure to drive the disc and control the disc opening to complete the function of pressure reduction and stabilization. Y42X direct-acting spring diaphragm pressure reducing valve can replace conventional zonal water pipes in the hot and cold water supply systems of urban buildings and high-rise buildings, saving equipment. It can also play a role in reducing pressure and stabilizing in the usual hot and cold water pipe network. Y42X type direct acting spring diaphragm pressure reducing valve has stable pressure regulation and pressure stabilization, which is suitable for water and non-corrosive liquid medium pipelines.