The valve has a wide range of uses, types and classification methods. The valve types can be divided into two categories:
A type of automatic valve: a valve that acts by itself depending on the capacity of the medium (liquid, gas) itself. Such as check valve, safety valve, regulating valve, drain valve, pressure reducing valve, etc.
The second type of actuated valve: a valve operated manually, electrically, hydraulically and pneumatically. Such as gate valve, globe valve, throttle valve, butterfly valve, ball valve, plug valve, etc.
In addition, there are the following methods for classification of valve types:
1、 The types of valves can be divided according to the structural characteristics and the direction of movement of the closing element relative to the valve seat
1. Shutter shape: the closing element moves along the center of the valve seat.
2. Gate shape: the closure moves along the center of the vertical valve seat.
3. Cock and ball: the closing part is a plunger or ball, which rotates around its centerline.
4. Swing shape; The closure rotates around an axis outside the valve seat.
5. Dish shape: the disc of the closing element rotates around the axis in the valve seat.
6. Spool valve shape: the closing element slides in the direction perpendicular to the channel.
The types of valves mainly include:
Plug valve, gate valve, globe valve, ball valve - used to open or close the medium flow in the pipeline.
Check valve (including bottom valve) - used to automatically prevent the backflow of medium in the pipeline. Throttle valve - used to regulate the flow of pipeline medium.
Butterfly valve - used to open or close the medium in the pipeline. It can also be used for adjustment.
Safety valve is used on boilers, vessels, equipment and pipelines. When the medium pressure exceeds the specified value, it can automatically eliminate the excess medium pressure to ensure the safety of production and operation.
Pressure reducing valve - used to automatically reduce the medium pressure in pipelines and equipment. When the medium passes through the clearance of the valve clack, resistance will be generated to cause pressure loss, so as to achieve the purpose of pressure reduction.
Steam trap - used to automatically drain condensate on steam pipeline to prevent steam loss or leakage.
2、 The types of valves can be divided according to their purposes
1. Disconnection: used to connect or cut off pipeline medium, such as stop valve, gate valve, ball valve, butterfly valve, etc.
2. Check: used to prevent the medium from backflow, such as check valve.
3. Regulating: used to regulate the pressure and flow of medium, such as regulating valve and pressure reducing valve.
4. Distribution: used to change the flow direction of media and distribute media, such as three-way cock, distribution valve, slide valve, etc.
5. Safety valve: when the medium pressure exceeds the specified value, it is used to discharge excess medium to ensure the safety of pipeline system and equipment, such as safety valve and emergency valve.
6. Other special purposes: such as steam trap, vent valve, blowdown valve, etc.
Valve types are classified according to use and function
Block valves: mainly used to cut off or connect medium flow. Including gate valve, globe valve, diaphragm valve, ball valve, plug valve, butterfly valve, plunger valve, ball plug valve, needle instrument valve, etc.
Regulating valves: mainly used to regulate the flow and pressure of media. Including regulating valve, throttle valve, pressure reducing valve, etc.
Check valves: used to prevent medium from backflow. Including check valves of various structures.
Diverter valve: used for separating, distributing or mixing media. Including distribution valves and steam traps of various structures.
Safety valves: used for safety protection in case of medium overpressure. Includes various types of safety valves.
3、 The types of valves can be divided according to the driving modes:
1. Manual: driven manually with the help of handwheel, handle, lever or chain wheel. When driving a large torque, worm gear, gear and other reduction devices are installed.
2. Electric: driven by motor or other electrical devices.
3. Hydraulic: driven by (water, oil).
4. Pneumatic; Drive with compressed air.
4、 The valve type can be divided according to the pressure and the nominal pressure of the valve:
1. Vacuum valve: the valve with pressure less than 0.1MPa, that is, 760mmHg, is usually expressed in mmHg or mmH2O.
2. Low pressure valve: valves with nominal pressure PN ≤ 1.6MPa (including steel valves with PN ≤ 1.6MPa)
3. Medium pressure valve: valve with nominal pressure of PN2.5-6.4MPa.
4. High pressure valve: valve with nominal pressure of PN10.0-80.0MPa.
5. Ultra high pressure valve: valve with nominal pressure PN ≥ 100.0MPa.
5、 The types of valves are classified according to the temperature of the medium, and can be classified according to the temperature of the medium when the valve is working:
1. Common valve: applicable to valves with medium temperature of - 40~425 ℃.
2. High temperature valve: applicable to valves with medium temperature of 425~600 ℃.
3. Heat resistant valve: applicable to the valve with medium temperature above 600 ℃.
4. Low temperature valve: applicable to valves with medium temperature of - 40~- 150 ℃.
5. Ultra low temperature valve: applicable to valves with medium temperature below - 150 ℃.
6、 The types of valves are classified according to their nominal diameters
1. Small diameter valve: valve with nominal diameter DN<40mm.
2. Medium diameter valve: valve with nominal diameter of DN50~300mm.
3. Large diameter valve: valve with nominal diameter of DN350~1200mm.
4. Extra large diameter valve: valve with nominal diameter DN ≥ 1400mm.
7、 The types of valves can be classified according to the connection mode of valves and pipes
1. Flanged valve: the valve body is equipped with a flange, and the valve is connected to the pipeline with a flange.
2. Threaded valve: the valve body is equipped with internal thread or external thread, and the valve is connected with the pipeline by thread.
3. Welding connection valve: the valve body is equipped with welded junction, and the valve is connected with the pipeline by welding.
4. Clamp connected valve: the valve body is equipped with a clamp, and the valve is connected with the pipeline by clamp.
5. Ferrule connecting valve: the valve connected with ferrule and pipeline.
8、 The valve type is classified according to the valve body material
Non metal material valve: such as ceramic valve, glass fiber reinforced plastic valve, plastic valve.
Metal material valves: such as copper alloy valve, aluminum alloy valve, lead alloy valve, titanium alloy valve, monel alloy valve, cast iron valve, carbon steel
Valves, cast steel valves, low alloy steel valves, high alloy steel valves.
Metal valve body lining valve: such as lead lined valve, plastic lined valve, enamel lined valve.
General classification of valve types
This classification method is more commonly used internationally and domestically at present, which is divided according to principle, function and structure. General gate valve, globe valve, throttle valve, instrument valve, plunger valve, diaphragm valve, plug valve, ball valve, butterfly valve, check valve, relief valve, safety valve, drain valve, regulating valve, bottom valve, filter, blowdown valve, etc. As the valve is widely used, it plays a very important role. For example, in power plants, valves can control the operation of boilers and steam turbines; In petroleum and chemical production, valves also control the normal operation of all production equipment and processes. This is also true in other departments. However, compared with other products, valves are often ignored. For example, when installing machinery and equipment, people tend to focus on the main machinery and equipment, such as compressors, high pressure vessels, boilers, etc; There are also some improper choices. These practices will reduce the overall production efficiency or stop production, or cause various other accidents. Therefore, the selection, installation and use of valves must be carefully and responsibly carried out. This is especially true for modern industrial production and construction.
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