(1) Pressure regulating range: it refers to the adjustable range of pressure-reducing valve output pressure P2, within which the specified accuracy is required.The regulating range is mainly related to the stiffness of the regulating spring. (2) Pressure characteristic: It refers to the characteristic of output pressure fluctuation caused by input pressure fluctuation when the flow rate G is fixed.The smaller the output pressure fluctuation, the better the performance of the relief valve.The output pressure must be lower than the input pressure-constant to be essentially unchanged by the input pressure. (3) Flow characteristics: it refers to the input pressure - timing, output pressure with the output flow g changes with the change of the durability.When the flow rate G changes, the smaller the output pressure change, the better.Generally, the lower the output pressure, the smaller the fluctuation with the output flow. It reduces the higher liquid pressure in the front line of the valve to the level required in the back line of the valve.The transmission medium here is mainly water.Pressure-reducing valves are widely used in high-rise buildings, urban water supply network areas with high water pressure, mines and other occasions to ensure that each water point in the water supply system to obtain appropriate service water pressure and flow.Since the leakage rate and waste degree of water are almost directly proportional to the water pressure of the water supply system, the pressure-reducing valve has the function of improving the operating conditions of the system and potentially saving water. According to statistics, the water-saving effect is about 30%. 1. Close the gate valve before the pressure reducing valve and open the gate valve after the pressure reducing valve to create the downstream low-pressure environment; 2. Adjust the screw Turn counterclockwise to the top position (relative to the lowest outlet pressure), then close the rear gate valve of the reducing valve; 3. Slowly open the gate valve in front of the relief valve until it is fully open; 4. Slowly rotate the adjusting screw clockwise to adjust the outlet pressure to the required pressure (subject to the gauge pressure behind the valve);After adjustment, the lock will be tightened Lock the nut and open the rear gate valve of the relief valve; 5. If the outlet pressure is higher than the set pressure during adjustment, it shall be adjusted from the first step, that is, it can only be adjusted from low pressure to high pressure.Principle of action: reducing pressure valve is by the local resistance of the flow of water in the valve passage to reduce water pressure, the scope of water pressure drop by connecting the valve disc film or piston on both sides of the inlet and outlet water pressure difference automatic regulation.The principle of constastant pressure reduction is to control the pressure ratio of the floating piston in the valve body, and the pressure ratio of the inlet and outlet ends is inversely proportional to the piston area ratio on the inlet and outlet sides.The pressure-reducing valve works smoothly and without vibration.There is no spring in the valve body, so there is no spring corrosion or metal fatigue failure.The sealing performance is good without leakage, thus reducing the dynamic pressure (when the water flows) and static pressure (when the flow is 0);Especially in the decompression without affecting the water flow. Working principle: the pressure reducing valve is a control valve open-close part of the opening in the body to adjust the flow of the medium, the medium pressure is reduced, at the same time with the aid of the role of the valve after pressure adjust the opening of open-close part, keep the valve after pressure within a certain range, and the valve body or valve after the injection of cooling water, reduce the temperature of medium, the valve is called desuperheating valve to relieve stress.Pressure reducing valve is selected for automatic selection.The characteristic of the valve is to keep the outlet pressure and temperature within a certain range in the case of constant change of inlet pressure. advantages Although the water flow through the pressure-reducing valve has a great loss of head, it is generally energy-saving because it reduces the waste of water, makes the system flow distribution reasonable, and improves the system layout and working condition.Medium for steam occasions, it is appropriate to choose the pilot piston type pressure relief valve or bellows type pressure relief valve.For ease of operation, adjustment and maintenance, pressure relief valves should generally be installed in horizontal piping.