The definition of "valve" is a device used to control the direction, pressure and flow of fluid in a fluid system. Valve is a device that makes the medium (liquid, gas, powder) in pipeline and equipment flow or stop, and can control its flow.
[Edit this paragraph] Classification of valves
1. Classification by function and purpose
(1) Block valve: Block valve, also called closed-circuit valve, is used to connect or cut off the medium in the pipeline. Block valves include gate valves, globe valves, plug valves, ball valves, butterfly valves and diaphragms.
(2) Check valve: Check valve, also known as check valve or check valve, is used to prevent the medium in the pipeline from flowing backwards. The bottom valve of water pump suction switch also belongs to the category of check valve.
(3) Safety valve: The function of the safety valve is to prevent the medium pressure in the pipeline or device from exceeding the specified value, so as to achieve the purpose of safety protection.
(4) Control valve: Control valve includes control valve, throttle valve and pressure reducing valve, and its function is to adjust parameters such as pressure and flow rate of medium.
(5) Diverter valve: Diverter valve includes various distribution valves and traps. Used to distribute, separate or mix the media in the pipeline.
(6) Exhaust valve: Exhaust valve is an indispensable auxiliary component in pipeline system, which is widely used in boilers, air conditioners, oil and gas, water supply and drainage pipelines. It is often installed at commanding heights or bends to remove excess gas in the pipeline, improve the efficiency of the pipeline and reduce energy consumption.
2. Classification by nominal pressure
(1) vacuum valve: refers to the valve whose working pressure is lower than the standard atmospheric pressure.
(2) Low pressure valve: refers to the valve with nominal pressure PN ≤ 1.6Mpa.
(3) Medium-pressure valves: refer to valves with nominal pressures PN of 2.5, 4.0 and 6.4Mpa.
(4) High-pressure valve: refers to the valve with nominal pressure PN of 10 ~ 80 MPa.
(5) Ultra-high pressure valve: refers to the valve with nominal pressure PN≥ 100Mpa.
3. Classification according to working temperature
(1) ultra-low temperature valve: used for working temperature t of medium.
(2) Low-temperature valve: used for valves with medium working temperature of-100℃ ≤ T ≤-40℃.
(3) Normal temperature valve: it is used for valves with medium working temperature of -40℃ ≤ T ≤ 120℃.
(4) Intermediate temperature valve: used for medium with working temperature of 120℃
(5) High temperature valve: used for working temperature of medium t >；; 450℃ valve.
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 act. Such as safety valve, pressure reducing valve, steam trap, check valve, automatic regulating valve, etc.
(2) Electric valve: Electric valve can be driven by various power sources.
Electric valve: A valve driven by electricity.
Pneumatic valve: A valve driven by compressed air.
Hydraulic valve: A valve driven by the pressure of a liquid, such as oil.
In addition, there are combinations of the above driving modes, such as pneumatic-electric valves.
(3) Manual valve: Manual valve is operated manually with the help of handwheel, handle, lever and sprocket. When the opening and closing torque of the valve is large, the wheel or worm gear reducer can be installed between the handwheel and the valve stem. Universal joints and transmission shafts can also be used for remote operation if necessary.
5. Classification by nominal diameter
(1) Small valves: valves with nominal diameter DN≤40mm.
(2) Intermediate diameter valve: a valve with a nominal diameter DN of 50 ~ 300mm.
(3) Large-diameter valves: valves with a nominal diameter of 350 ~ 1200mm.
(4) Extra-large-diameter valves: valves with nominal diameter dn ≥1400 mm. ..
6. Classification by structural features
(1) gate valve: the opening and closing parts (disc) are driven by the valve stem to move up and down along the center line of the valve seat;
(2) Plug valve: the opening and closing part (gate valve) is driven by the valve stem and moves up and down along the center line perpendicular to the valve seat;
(3) Plug valve: the opening and closing part (cone plug or ball) rotates around its own center line;
(4) Swing valve: the opening and closing part (disc) rotates around the shaft outside the valve seat;
(5) Butterfly valve: the opening and closing part (disc) rotates around the fixed shaft in the valve 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: The valve body has internal thread or external thread, which is connected with the pipeline through thread.
(2) Flange valve: The valve body is connected by flange and connected with the pipeline flange.
(3) Welding connecting valve: The valve body has a welding groove and is welded with the pipeline.
(4) Clamp connection valve: The valve body has a clamp and is connected with the pipe clamp.
(5) Socket-type connecting valve: connected to the pipeline through a ferrule.
(6) Clamping valve: a connection form that directly clamps the valve and two pipelines together with bolts.
8. Classification according to valve body materials
(1) metal valve: Its valve body and other parts are made of metal. 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, etc.
(2) Non-metallic valve: Its valve body and other parts are made of non-metallic materials. Such as plastic valves, ceramic valves, enamel valves, FRP valves, etc.
(3) Metal-lined valve body: The valve body is made of metal, and all the main surfaces in contact with the medium are lined, such as rubber-lined valves, plastic-lined valves and ceramic-lined valves.
9. Valve model arrangement
The valve model should usually indicate the valve type, driving mode, connection form, structural characteristics, sealing surface material, valve body material and nominal pressure. The standardization of valve models provides convenience for the design, selection and sale of valves. Nowadays, there are more and more types and materials of valves, and the model compilation of valves is becoming more and more complicated. Although there is a unified standard for valve model compilation in China, it is increasingly unable to meet the needs of the development of the valve industry. At present, valve manufacturers generally adopt a unified numbering method; If the unified numbering method cannot be adopted, each production enterprise shall formulate the numbering method according to its own needs.
The valve model compilation method is applicable to gate valves, throttle valves, ball valves, butterfly valves, diaphragm valves, plunger valves, plug valves, check valves, safety valves, pressure reducing valves and steam traps of industrial pipelines. Including valve model compilation and valve naming.
Valves have a wide range of uses and classification methods. Generally can be divided into two categories:
The first type of automatic valve: a valve that acts by itself depending on the ability of the medium (liquid, gas). Such as check valves, safety valves, regulating valves, steam traps, pressure reducing valves, etc.
The second drive valve: a valve operated by manual, electric, hydraulic and pneumatic means. Such as gate valves, globe valves, throttle valves, butterfly valves, ball valves, plug valves, etc.
In addition, there are several valve classification methods:
A, according to the structural characteristics, according to the direction of movement of the closing piece relative to the valve seat, can be divided into:
1. globe valve shape: the closing piece moves along the center of the valve seat.
2. Gate shape: The closing member moves along the center of the vertical valve seat.
3. Cock and ball: The closing part is a plunger or ball that rotates around its own center line.
4. Rotate the shape; The closing member rotates around an axis outside the valve seat.
5. Dish-shaped: the disc of the closing part rotates around the shaft in the valve seat.
6. Slide valve shape: the closing piece slides in the direction perpendicular to the channel.
According to the structure type, mainly include:
Plug valve, gate valve, globe valve and ball valve-used to open or close the medium flow in the pipeline.
Check valve (including bottom valve)-used to automatically prevent the medium in the pipeline from flowing backwards. Throttle valve-used to adjust the flow of pipeline medium.
Butterfly valve-used to open or close the medium in the pipeline. It can also be used to adjust.
Safety valve-for boilers, container 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 pressure of medium in pipelines and equipment. When the medium passes through the clearance of the valve disc, it produces resistance, resulting in pressure loss and achieving the purpose of pressure reduction.
Trap-used to automatically drain the condensed water in the steam pipeline to prevent steam loss or leakage.
Second, according to the purpose, according to the purpose of different valves can be divided into:
1. opening and closing function: used to connect or cut off pipeline media, such as globe valves, gate valves, ball valves and butterfly valves.
2. Non-return purpose: used to prevent medium from flowing back, such as check valve.
3. Adjustment: used to adjust the pressure and flow of medium, such as regulating valve and reducing valve.
4. Distribution: used to change the flow direction of medium and distribute medium, such as three-way cock, distribution valve and slide valve.
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 accident valve.
6. His special uses: such as steam traps, exhaust valves, sewage valves, etc. & lt！ [endif]& gt；
Classification by purpose and function
Block valve-mainly used to block or connect the medium flow. Including gate valves, globe valves, diaphragm valves, ball valves, plug valves, disc valves, plunger valves, spherical plug valves, needle instrument valves, etc. Regulating valve-mainly used to regulate the flow and pressure of medium. Including regulating valve, throttle valve, pressure reducing valve, etc.
Check valve-used to prevent medium from flowing back. Include check valves of various structures.
Diverter valve-used to separate, distribute or mix media. Include distribution valves and traps of various structures.
Safety valve-used for safety protection when the medium is overpressure. Include various types of safety valves.
Three, according to the driving mode, according to the different driving modes can be divided into:
1. Manual: With the help of handwheel, handle, lever or sprocket, it is driven by human power. When transmitting large torque, it is equipped with worm gear, gear and other deceleration devices.
2. Electric: Driven by a motor or other electric device.
3. Hydraulic: Driven by (water, oil).
4. Pneumatic; Driven by compressed air.
Four, according to the pressure, according to the nominal pressure of the valve can be divided into:
1. vacuum valve: absolute pressure
The water column represents pressure.
2. Low-pressure valves: valves with nominal pressure PN≤ 1.6MPa (including steel valves with PN≤ 1.6MPa).
3. Medium pressure valve: a valve with a nominal pressure of PN 2.5-6.4 MPa.
4. High-pressure valve: a valve with a nominal pressure of PN 10.0-80.0 MPa.
5. Ultra-high pressure valves: valves with nominal pressure pn ≥100.0mpa. ..
Five, according to the temperature of the medium, according to the temperature of the valve working medium can be divided into:
1. Ordinary valves: Suitable for valves with medium temperature of -40 ~ 425℃.
2. High temperature valve: It is suitable for valves with medium temperature of 425 ~ 600℃.
3. Heat-resistant valves: Suitable for valves with medium temperature above 600℃.
4. Low temperature valve: it is suitable for valves with medium temperature of -40 ~- 150℃.
5. Ultra-low temperature valve: suitable for valves with medium temperature below-150℃.
Six, according to the nominal diameter, the valve according to the nominal diameter can be divided into:
1. Small caliber valve: valve with nominal diameter DN < 40mm.
2. Medium caliber valve: a valve with a nominal diameter of DN50~300mm.
3. Large-diameter valves: valves with nominal diameters of DN 350 ~ 1200mm.
4. Extra-large-diameter valves: valves with nominal diameter dn ≥1400 mm. ..
Seven, according to the connection with the pipeline, according to the connection between the valve and the pipeline;
1. Flanged valve: a valve with a flange on the valve body and connected to the pipeline through the flange.
2. Threaded valve: a valve with internal thread or external thread in the valve body and threaded connection with the pipeline.
3. Welded connection valve: There is a welded joint on the valve body, and the valve is welded with the pipeline.
4. Clamp connection valve: a valve with a clamp on the valve body and connected to the pipeline through the clamp.
5. Valve connected with ferrule: a valve connected with pipeline through ferrule.
Classification by valve body material
Non-metallic valves-such as ceramic valves, FRP valves and plastic valves.
Metal valves-such as copper alloy valves, aluminum alloy valves, lead alloy valves, titanium alloy valves, Monel alloy valves, cast iron valves and carbon steel.
Valve, cast steel valve, low alloy steel valve, high alloy steel valve.
Metal body lined valves-such as lead lined valves, plastic lined valves and enamel lined valves.
Universal classification
This classification method is divided according to principle, function and structure, and it is the most commonly used classification method at home and abroad. Generally, there are gate valves, globe valves, throttle valves, instrument valves, plunger valves, diaphragm valves, plug valves, ball valves, butterfly valves, check valves, safety valves, steam traps, regulating valves, bottom valves, filters, sewage valves, etc. Because the valve is widely used, it plays a great 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 technological processes. The same is true of other departments. However, compared with other products, valves are often neglected. For example, when installing machinery and equipment, people often focus on the main machinery and equipment.
Aspects, such as: compressors, high-pressure vessels, boilers, etc. ; Some of them are not well chosen. These practices will reduce the overall production efficiency or stop production, or cause other accidents. Therefore, the selection, installation and use of valves must be
Carry out serious and responsible work. This is especially true for modern industrial production and construction.
[Edit this paragraph] Explanation of valve terms
The sealing performance of the valve refers to the ability of each sealing part of the valve to prevent medium leakage, which is the most important technical performance index of the valve. There are three sealing parts of the valve: the contact between the opening and closing part and the two sealing surfaces of the valve seat; Matching position of packing with valve stem and stuffing box; The joint of valve body and bonnet. The former leakage is called internal leakage, which is usually called lax closure, which will affect the valve's ability to cut off the medium. For block valves, internal leakage is not allowed. The latter two kinds of leakage are called external leakage, that is, the medium leaks from the inside of the valve to the outside of the valve. Leakage will cause material losses, pollute the environment, and even cause accidents in serious cases. For flammable, explosive, toxic or radioactive media, leakage is not allowed, so the valve must have reliable sealing performance.
[Edit this paragraph] Valve model set
Valve model compilation method and valve number description
Valve model should usually indicate the valve type, driving mode, connection form, structural characteristics, nominal pressure, sealing surface material, valve body material and other elements. The standardization of valve models provides convenience for the design, selection and distribution of valves. Nowadays, there are more and more types and materials of valves, and the compilation of valve models is becoming more and more complicated. Although there is a unified standard for valve model compilation in China, it can not meet the needs of the development of valve industry gradually. At present, valve manufacturers generally adopt a unified numbering method; If a unified numbering method cannot be adopted, each manufacturer can make a numbering method according to its own situation.
One unit, two units, three units, four units, five units-six units, seven units.
Valve type, transmission mode, connection type, structural form, sealing pair material-nominal pressure valve body material
Unit 1: valve type code type safety valve butterfly valve diaphragm valve check valve
Bottom valve stop valve throttle valve drain valve ball valve drain valve plunger valve pressure reducing valve gate valve
Code A D G H J L P Q S U X Y Z