Type 300X slow closing check valve from the main valve, check valve, needle valve, ball valve, micro-filter and pressure gauge water control valves over the system. The use of hydraulic automatic operation, can get the best of the main valve opening and closing speed. Prevent water hammer water hammer generation, in order to achieve the effect of slow closing muffler, when the valve from the inlet end of the water supply, the water through a microfilter, needle valve, check valve into the main valve control room, and then through the drainage valve downstream. Because the needle valve opening degree of opening is less than that of the main valve control room faster than water drainage speed, so the control room pressure is reduced, the role of opening the main valve inlet pressure on the lower end of the main valve disc to the downstream water supply. When the pipe to stop water supply, if the downstream water began to reflux, a part of the water through the valve back into the main control room, the one-way valve action, return water can not flow out from the main control room, causing the main control room gradually boost, slowly close the main valve The products use the hydraulic self-control, no other devices and energy, maintenance is simple, open and close smoothly slow. This valve products are widely used in high-rise buildings, living quarters and other water supply systems and urban water supply project.