According to the different functions of open and close valves, there are many kinds of classificatio
1. Classification by function and use
(1) Cut-off valve: Cut-off valve, also known as closed-circuit valve, its role is to connect or cut off the medium in the pipeline. Interception valves include gate valves, globe valves, cock valves, ball valves, butterfly valves and diaphragms.
(2) Check valve: Check valve is also known as one-way valve or check valve. Its function is to prevent medium backflow in the pipeline. The bottom valve of pump suction closure also belongs to check valve type.
(3) Safety valves: The function of safety valves is to prevent the medium pressure in pipes or devices from exceeding the prescribed value, so as to achieve the purpose of safety protection.
(4) Regulating valves: Regulating valves include regulating valves, throttle valves and pressure relief valves, whose functions are to regulate the pressure and flow of medium.
(5) Shunt-off valves: Shunt-off valves include various distribution valves and traps, whose function is to distribute, separate or mix the media in the pipeline.
2. Classification by nominal pressure
(1) Vacuum valve refers to a valve whose working pressure is lower than the standard atmospheric pressure.
(2) Low pressure valve refers to a valve with nominal pressure PN < 1.6Mpa.
(3) Medium pressure valve refers to the valve with nominal pressure PN of 2.5, 4.0 and 6.4 Mpa.
(4) High-pressure valve refers to a valve with a nominal pressure of 10-80 Mpa.
(5) Ultra-high pressure valve refers to the valve with nominal pressure PN (> 100Mpa).
3. Classification by working temperature
(1) Ultra-low temperature valves: valves for medium working temperature t<-100 C.
(2) cryogenic valve: valve used for medium working temperature - 100 C < T < 40 ~C.
(3) Normal Temperature Valve: Valve for medium working temperature - 40 t 120 C.
(4) Medium Temperature Valve: Used for medium working temperature 120 C
(5) High temperature valves: valves for medium working temperature T > 450 C.
4. Classification by Driving Mode
(1) Automatic valve refers to a valve that does not need external force to drive, but relies on the energy of the medium itself to make the valve operate. Such as safety valve, pressure relief valve, trap, check valve, automatic control valve, etc.
(2) Power drive valve: Power drive valve can be driven by various power sources.
Electric Valve: Valve driven by electricity.
Pneumatic valve: Valve driven by compressed air.
Hydraulic valve: Valve driven by liquid pressure such as oil.
In addition, there are several combinations of the above driving modes, such as gas-electric valves.
(3) Manual valves: Manual valves operate valves by manpower with the help of handwheels, handles, levers and sprockets. When the opening and closing moment of the valve is large, the wheel or worm gear reducer can be set between the handwheel and the valve stem. If necessary, the universal joint and transmission shaft can also be used for long-distance operation.
5. Classification by nominal path
(1) Small-diameter valves: valves with nominal diameter DN < 40mm.
(2) Medium-sized valves: valves with nominal diameter DN of 50-300 mm.
(3) Large-diameter valves: Valves with nominal DN of 350-1200 mm.
(4) Extra large diameter valve: valve with nominal diameter DN (> 1400mm).
6. Classification by Structural Characteristics
(1) Shut-off valve: the opening and closing parts (discs) are driven by the stem to move up and down along the center line of the seat;
(2) Cock valve: the opening and closing parts (gate valve) are driven by the valve stem to move up and down perpendicular to the center line of the valve seat.
(3) Cock valve: the opening and closing parts (cone plug or ball) revolve around their own central line;
(4) Swing valve: the opening and closing parts (discs) revolve around the axis outside the seat;
(5) Butterfly valve: the opening and closing parts (discs) rotate around the fixed axis in the seat;
(6) Slide valve: The opening and closing parts slide in the direction perpendicular to the channel.
7. Classification by connection method
(1) Threaded connection valve: valve body with internal or external threads, and pipe threads.
(2) Flanged connection valve: The valve body is flanged and connected with the pipeline flange.
(3) Welded connection valve: The valve body has a welding groove, which is welded to the pipeline.
(4) Clamp connection valve: valve body with clamp, and pipe clamp connection.
(5) Sleeve connection valve: Sleeve connection with pipeline.
(6) Connecting valves with pairs of clamps: the connecting form of directly clamping the valves and the two ends of the pipeline with bolts.
8. Classification by valve body material
(1) Metal material valves: The valve body and other parts are made of metal materials, such as cast iron valves, carbon steel valves, alloy steel valves, copper alloy valves, aluminum alloy valves, lead alloy valves, titanium alloy valves, Monel alloy valves and so on.
(2) Non-metallic material valves: The valve body and other parts are made of non-metallic materials, such as plastic valves, ceramic valves, enamel valves, FRP valves and so on.
(3) Metal body lining valves: the body of the valve is metal, and the main surface contacting with the medium inside is lined, such as rubber-lined valves, plastic-lined valves, pottery-lined valves and so on.