Air pressure regulator adjusts the flow of the medium by controlling the opening degree of the opening and closing parts in the valve body, reduces the pressure of the medium, and adjusts the opening degree of the opening and closing parts with the help of the pressure behind the valve, so that the pressure behind the valve is kept within a certain range. Inside, and spray cooling water in the valve body or behind the valve to reduce the temperature of the medium, this kind of valve is called a pressure reducing and desuperheating valve. The characteristic of this valve is to keep the outlet pressure and temperature within a certain range when the inlet pressure is constantly changing. The pressure reducing valve is an essential 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 a stable air source power for adjustment and control. This type of valve should generally be installed horizontally in the pipeline.