Function of pressure reducing valve

Function of pressure reducing valve

The pressure reducing valve adjusts the flow of the medium by controlling the opening of the opening and closing parts in the valve body to reduce the pressure of the medium. At the same time, the opening of the opening and closing parts is adjusted by the action of the pressure behind the valve, so that the pressure behind the valve is kept within a certain range. In the case of constant changes in the inlet pressure, the outlet pressure is kept within the set range, and the subsequent living and production appliances are protected.

1. The gas pressure reducing valve is a necessary accessory of the pneumatic control valve. Its main function is to reduce the pressure of the air source and stabilize it to a fixed value, so that the control valve can obtain stable air source power for regulation and control.

2. According to the structural form, it can be divided into diaphragm type, spring film type, piston type, lever type and bellows type; According to the number of valve seats, it can be divided into single seat type and double seat type; According to the position of the valve disc, it can be divided into positive action type and reverse action type. In short, the overflow pressure reducing valve is reduced by the throttling action of the air inlet, stabilized by the balance of the force on the diaphragm and the overflow action of the overflow hole; The output pressure can be changed within a certain range by adjusting the spring. In order to prevent the pollution of the surrounding environment caused by a small amount of gas released from the above overflow type pressure reducing valve, the pressure reducing valve without overflow valve (i.e. ordinary pressure reducing valve) can be used. Basic performance of pressure reducing valve

（1）Pressure regulation range: it refers to the adjustable range of the output pressure P2 of the pressure reducing valve, within which the specified accuracy is required. The pressure regulating range is mainly related to the stiffness of the pressure 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 constant. The smaller the output pressure fluctuation, the better the characteristics of the pressure reducing valve. The output pressure must be lower than the input pressure - the fixed value will not change with the input pressure. R't8 (3) flow characteristic: it refers to the persistence of input pressure timing and output pressure changing with the change of output flow. When the flow rate changes, the smaller the change in the output pressure, the better. Generally, the lower the output pressure, the smaller the fluctuation with the change of output flow.

How to select pressure reducing valve

1. Select the type and pressure regulation accuracy of the pressure reducing valve according to the use requirements, and then select its diameter according to the required maximum output flow. When determining the air source pressure of the valve, make it greater than the maximum output pressure by 0.1MPa. The pressure reducing valve is generally installed after the water separator air filter and before the oil mist or setting device, and attention shall be paid not to connect its inlet and outlet reversely; When the valve is not in use, the knob should be loosened to prevent the diaphragm from being deformed under pressure and affecting its performance.

2. Attention shall be paid to the following matters in the installation and maintenance of pressure reducing valve:

（1）.In order to facilitate operation and maintenance, the valve is generally installed vertically on the horizontal pipeline.

（2）The pressure reducing valve must be installed in strict accordance with the arrow direction on the valve body to keep consistent with the fluid flow direction. If the water quality is not clean and contains some impurities, a filter must be installed at the upstream water inlet of the pressure reducing valve (we suggest that the filter precision should not be less than 0.5mm).

（3）In order to prevent overpressure behind the valve, a pressure reducing valve shall be installed at least 4m away from the valve outlet.

（4）The pressure reducing valve plays a certain check role in the pipeline. In order to prevent the harm of water hammer, a small expansion tank can also be installed to prevent damage to the pipeline and valves. The filter must be installed in front of the inlet pipe of the pressure reducing valve, and the expansion tank must be installed behind the outlet pipe of the pressure reducing valve! W0B4O8（5）. If you need to install the pressure reducing valve in the hot water system, you must install a check valve between the pressure reducing valve and the expansion tank. In this way, the expansion tank can not only absorb the volume of water increased due to thermal expansion, but also prevent the influence of hot water backflow or pressure fluctuation on the pressure reducing valve, so as to ensure the normal operation of the pressure reducing valve for a long time.

3. Function and application of pressure reducing valve:

The pressure reducing valve mainly controls the fixed outlet pressure of the main valve. The outlet pressure of the main valve does not change due to the change of the inlet pressure or the change of the outlet flow of the main valve. It is applicable to industrial water supply, fire water supply and domestic water pipe network system“