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Valve ClassificationValve Definition: “The definition of "valve" is a device used to control the direction, pressure, and flow of fluid in a fluid system. A valve is a device that allows or stops the flow of media (liquid, gas, powder) in piping and equipment, and controls its flow rate. Classification by use and function 1. Cut-off valves : Mainly used to cut off or connect the medium flow. Including gate valves, globe valves, diaphragm valves, ball valves, plug valves, butterfly valves, plunger valves, ball plug valves, needle instrument valves, etc. 2. Regulating valves: Mainly used to adjust the flow rate and pressure of the medium. Including regulating valves, throttle valves, pressure reducing valves, etc. 3. Check valves: Used to prevent media from flowing back. Including check valves of various structures. 4. Diverter valves : For separating, distributing or mixing media. Including distribution valves and traps of various structures. 5. Safety valves: Used for safety protection when medium overpressure. Includes various types of safety valves. Classification by pressure 1. Vacuum valve : Valves with working pressures lower than standard atmospheric pressure. 2. Low pressure valve: Valves with nominal pressure PN less than 1.6MPa. 3. Medium pressure valve : Valves with nominal pressure PN 2.5~6.4MPa. 4. High pressure valve : Valves with nominal pressure PN10.0~80.0MPa. 5. Ultra-high pressure valve: Valves with nominal pressure PN greater than 100MPa. Classification by operating temperature 1. Ultra-low temperature valve: Valve for medium working temperature t450℃. Classification by nominal diameter 1. Small diameter valves: Valves with nominal diameter DN≤40mm. 2. Medium diameter valve: Valves with nominal diameter DN of 50 to 300mm. 3. Large diameter valve: The nominal valve DN is a valve with a diameter of 350 to 1200mm. 4. Extra large diameter valve: Valves with nominal diameter DN≥1400mm. Classification by connection method 1. Threaded connection valves: The valve body has internal or external threads and is threaded with the pipe. 2. Flange connection valve: The valve body is equipped with a flange and is connected to the pipe flange. 3. Welding connection valve: The valve body has a welding groove or socket, which is welded to the pipe. 4. Clamp connection valve: The valve body is equipped with a clamp port and is connected to the pipe clamp. 5. Card sleeve connection valve: It is connected with the pipe using a ferrule. 6. Clamp connection valve: Use bolts to directly clamp the valve and the pipes at both ends together. Classification by valve body material 1. Non-metallic material valves: Such as ceramic valves, fiberglass valves, plastic valves. 2. Metal valves: Such as copper alloy valves, aluminum alloy valves, lead alloy valves, titanium alloy valves, Monel alloy valves 3, cast iron valves, carbon steel valves, cast steel valves, low alloy steel valves, high alloy steel valves. 4. Metal body lined valves: Such as lead-lined valves, plastic-lined valves, and enamel-lined valves. Classification by driving mode 1. Automatic valve: It refers to a valve that does not require external driving, but relies on the energy of the medium itself to operate the valve. Such as safety valves, pressure reducing valves, traps, check valves, automatic regulating valves, etc. 2. Power driven valve: Power-driven valves can be driven using a variety of power sources. 3. Electric valve: With the help of electrically driven valves. 4. Pneumatic valve: Valve driven by compressed air. 5. Hydraulic valve: A valve driven by pressure from a liquid such as oil. In addition, there are combinations of the above driving methods, such as gas-electric valves, etc. 6. Manual valve: Manual valves use handwheels, handles, levers, and sprockets to control valve movements manually. When the valve opening and closing torque is large, this wheel or worm gear reducer can be installed between the handwheel and the valve stem.