Working principle and selection skills of pressure reducing valve

The working principle of the pressure reducing valve
    The pressure reducing valve is an essential accessory of the pneumatic regulating valve. The main function is to decompress and stabilize the pressure of the air source to a fixed value, so that the regulating valve can obtain stable air source power for adjustment control. According to the structure, it can be divided into film type, spring film type, piston type, lever type and bellows type; the number of seat seats can be artificial single seat type and double seat type; according to the position of the valve flap, it can be divided into positive action type and Reactionary.
    When the output pressure of the pressure reducing valve is high or the diameter is large, the pressure is directly adjusted by the pressure regulating spring, the spring stiffness is inevitably too large, and when the flow rate changes, the output pressure fluctuates greatly, and the structural size of the valve also increases. In order to overcome these disadvantages, a pilot type pressure reducing valve can be employed. The working principle of the pilot type pressure reducing valve is basically the same as that of the direct acting type. The pressure regulating gas used in the pilot type pressure reducing valve is supplied by a small direct acting pressure reducing valve. If the small direct acting pressure reducing valve is installed inside the valve body, it is called the internal pilot type pressure reducing valve; if the small direct acting pressure reducing valve is installed outside the main valve body, it is called the external pilot type pressure reducing valve. . Figure 14-2 shows the structure of the internal pilot type pressure reducing valve. Compared with the direct acting pressure reducing valve, the valve is composed of the nozzle 4, the baffle 3, the fixed orifice 9 and the air chamber B. The nozzle baffle enlarges the link. When the distance between the nozzle and the baffle changes slightly, the pressure in the B chamber changes significantly, causing a large displacement of the diaphragm 10 to control the up and down movement of the spool 6 to advance The valve port 8 is opened or closed to increase the sensitivity to the spool control, that is, the voltage regulation accuracy is improved.