The mechanism of pressure relief valves
The sanitary pressure relief valve is an essential component of pneumatic sanitary regulating valves. Its main use is to reduce the pressure of the gas source and to stabilize it to a fixed value so that the regulating valve can get a stable gas source force for regulating. According to structural type, they can be divided into film type, spring film type, piston type, lever type and bellow type. According to the number of valve seats, they can be divided into single seat type and double-seat type. According to the position of the valve gate, they can be divided into positive-acting type and reaction type.
When the pressure relief valve’s output pressure is high or the diameter is large, regulating the pressure using a regulator spring will make the stiffness of the spring too big. When flow change, the output pressure has a big fluctuation, so the structural size of the sanitary valve will increase, too. In order to overcome these shortcomings, pilot-type pressure relief valves can be used.
The mechanism of pilot-type pressure relief valves is basically the same as that of the direct-acting type. The regulating gas that the pilot-type pressure relief valve uses is supplied by small direct-acting pressure relief valve. If the small direct-acting pressure relief valve is installed inside the valve, then it’s known as the internal pilot-type pressure relief valve. If the small direct-acting pressure relief valve is installed outside the valve, then it’s known as the external pilot-type pressure relief valve.