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H104X piston type adjustable pressure relief valve is a special valve installed in the water supply and drainage system pipeline of high-rise buildings and reduces the inlet pressure to a required outlet pressure.The valve itself, rely on energy to keep exports stable in value, the outlet pressure does not change because of the change of inlet pressure and flow rate, and the valve at the inlet of the control system has a self-cleaning filter, the use of fluid properties, the proportion is larger and larger diameter of suspended particles will not enter the control system, ensure system circulation unobstructed, enables the valve to run safely and reliably.The system has stable operation, high strength and long service life.Piston type for valves larger than DN450mm diameter.