Little knowledge about pressure relief valves

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A pressure reducing valve is a valve that reduces the inlet pressure to a desired outlet pressure through regulation, and relies on the energy of the medium itself to maintain the outlet pressure stable automatically. From a fluid dynamics perspective, a pressure reducing valve is a throttling element whose local resistance can be varied; by changing the throttling area, the flow velocity and the kinetic energy of the fluid are altered, resulting in different pressure losses and thus achieving the purpose of pressure reduction. Then, through the regulation of the control and adjustment system, the fluctuations in the pressure behind the valve are balanced with the spring force, allowing the pressure there to remain constant within a certain error range. Experts say that a pressure relief valve is a specialized device designed to automatically reduce the operating pressure in a pipeline; it can lower the high liquid pressure in the pipeline before the valve to the level required in the pipeline after the valve. The transmission medium here is mainly water. Pressure relief valves are widely used in high-rise buildings, areas with excessively high water pressure in urban water supply networks, mines, and other settings, to ensure that all water usage points in the supply system receive an appropriate water pressure and flow rate. Given that the rate of water loss and waste is almost directly proportional to the water pressure in the supply system, pressure reducing valves can improve the operating conditions of the system and help save water; statistics show that their water-saving effect is approximately 30%. There are many types of construction for pressure relief valves; common ones in the past included diaphragm type and internal spring piston type. The basic working principle of a pressure reducing valve is to reduce water pressure by creating local resistance to the flow of water within the valve’s flow channels; the range of pressure reduction is automatically adjusted by the pressure difference between the inlet and outlet waters on either side of the diaphragm or piston that connects the valve disc. In 2007, Shanghai MinGao Valve Co., Ltd. introduced foreign technology to produce new types of pressure regulators, such as ratio-controlled pressure regulators. The principle of proportional pressure reduction relies on the control of water pressure at the floating piston within the valve body; the pressure reduction ratio at the inlet and outlet ends is inversely proportional to the ratio of the piston areas on those sides. This type of pressure reducing valve operates smoothly without vibration, which further enhances the production technology for such valves in China ； There are no springs inside the valve body, so there is no risk of spring corrosion or metal fatigue failure ； It has good sealing properties and does not leak, thereby reducing both dynamic pressure (when water is flowing) and static pressure (when the flow rate is 0) ； In particular, it does not affect the water flow rate while reducing pressure. Pressure relief valves are generally available in various sizes ranging from DN15 to DN100, with the operating pressures before and after the valve being respectively