One, the function of different
1, pressure reducing valve is a high pressure in the system to reduce the medium to a low pressure medium and keep the pressure stable valve varieties, pressure reducing valve is characterized by constant changes in the inlet pressure, to maintain the outlet pressure or temperature value within a certain range.
2, pressure relief valve is also a safety valve, mainly used in excessive pressure occasions, when the pressure is greater than the set value of the valve piece is open in time to release the pressure, the pressure is reduced to return to its original position, and the difference between the safety valve is not very much, the pressure relief valve refers to more than for liquids, safety valves refer to more than for gas, steam.
Second, the principle of different
1, pressure relief valve is composed of needle valve I, pressure gauge 2, the main valve 3, pilot valve 4 and connecting pipe and other components.
It is a kind of hydraulic control valve. The main valve is divided into upper and lower parts by the diaphragm, the lower chamber of the diaphragm is the water flow channel, and the upper chamber is the control chamber, which controls the opening and closing of the main valve flap. Pilot valve itself is a pressure relief valve, it also has a control room and water flow channel, valve opening and closing by the control room control. Needle valve that throttle valve, it controls the flow of water in the connection pipe.
2, pressure-reducing valve is used to control the valve body of the opening and closing parts of the opening to regulate the flow of the medium, the medium pressure reduction, while regulating the opening and closing parts of the opening with the help of the role of the valve pressure, so that the pressure after the valve to remain within a certain range, and in the valve body or the valve after the spray into the coolant, the temperature of the medium to reduce the temperature of the valve is known as a pressure-reducing thermostatic valves.
Pressure reducing valve fast and easy automation selection has included. The valve is characterized by a constant change in inlet pressure, to maintain the outlet pressure and temperature values within a certain range.
Three, categorized differently
1, pressure relief valve structure there are two main categories: spring-loaded and lever-loaded.?
Spring type is the valve valve and seat sealing by the force of the spring.
Lever type is to rely on the lever and the force of the weight.?
With the need for large capacity, there is another pulse-type pressure relief valve, also known as pilot-operated pressure relief valve, consists of the main relief valve and auxiliary valve. When the pressure of the medium in the pipeline exceeds the specified pressure value, the auxiliary valve opens first, and the medium enters the main relief valve along the conduit, and opens the main relief valve to reduce the increased medium pressure.
2, pressure reducing valves can be divided into membrane type, spring membrane type, piston type, lever type and bellows type according to structural form; according to the number of seats can be artificial single-seat and double-seat type; according to the position of the valve valve valve can be divided into positive and negative action type.
Pilot-operated pressure reducing valve when the output pressure of the pressure reducing valve is higher or larger diameter, with the regulator spring directly regulating the pressure, then the spring stiffness is bound to be too large, the flow changes, the output pressure fluctuation is larger, the valve structure will also increase the size. In order to overcome these shortcomings, pilot operated pressure reducing valves can be used. Pilot-operated pressure reducing valves work on the same principle as the direct-acting ones.
Pilot-operated pressure reducing valve used to regulate the gas, 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 internal pilot-operated pressure reducing valve; if the small direct-acting pressure reducing valve is installed outside the main valve body, it is called external pilot-operated pressure reducing valve.
Baidu Encyclopedia - Pressure Reducing Valve
Baidu Encyclopedia - Pressure Relief Valve