Reducing temperature and reducing valve is the control valve body opening and closing pieces of the opening to regulate the flow of media to reduce the pressure of the media, reducing pressure relief valve at the same time by virtue of the role of the pressure valve to adjust the opening and closing pieces of the opening and closing After the valve to maintain a certain pressure in the range, and in the valve body or after injection of cooling water, the media temperature decreases, this valve is called decompression valve. The characteristic of this valve is to keep the outlet hearing pressure and temperature within a certain range under the condition that the inlet pressure is constantly changing. Pressure reducing valve is an essential part of the pneumatic control valve, the main role is to depressurize the pressure of the gas source and stabilized to a fixed value, so that the control valve can obtain stable air source power for regulation and control. According to the structure of the form can be divided into film, spring film, piston, lever and bellows; according to the number of seats can be single-seat and two-seat; according to the location of the valve can be divided into positive and positive Reaction type. By using the medium can be divided into steam valve, air valve, gas valve and so on.