Technology definitions
Chinese Name: Valve
English name: valve
Definition 1: The device used to control the flow in the pipeline.
Subjects: Electric power (a subject); Hydraulic construction (two subjects)
Definition 2: The equipment installed in the pressure pipeline to control the flow of water.
Subjects: Hydraulic Science and Technology (a subject); Hydraulic construction (two subjects); Gates and hoists (three subjects)
valve
The valve is a control component in the fluid delivery system and has functions such as cut-off, regulation, diversion, reverse flow, pressure regulation, diversion, or pressure relief. Valves used in fluid control systems, ranging from the simplest shut-off valves to various valves used in highly sophisticated automatic control systems, are quite diverse in variety and size. Valves can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, slurries, oils, liquid metals, and radioactive media.
Valve history
The valve is created with the fluid line. The use of valves by humans has been nearly 4,000 years old. In ancient China, when salt was sucked from salt wells, they used cork valves in bamboo pipes. In 1800 BC, ancient Egyptians built large-scale water conservancy projects to prevent the flooding of the Nile, and similar wooden cocks were used to control the distribution of water. These are the prototypes of the valve . The extensive use of industrial valves began after Watt invented the steam engine. At the beginning of the 20th century, valves for cast steel, forged steel and forged welded structures appeared .
The definition of the valve
"Valve" is defined as a device used to control the direction, pressure, and flow of a fluid in a fluid system. The valve is a device that allows the flow or stop of the medium (liquid, gas, powder) in the piping and equipment and can control its flow.
The valve is the control component in the pipeline fluid delivery system. It is used to change the section of the passage and the direction of the medium flow. It has the functions of diversion, cut-off, regulation, throttling, non-return, diversion, or pressure relief. Valves for fluid control , ranging from the simplest stop valve to various valves used in highly complex automatic control systems, are available in a wide range of sizes and sizes. The valve 's nominal diameter ranges from extremely small gauge valves up to 10m in diameter. Industrial pipeline valves. The valve can be used to control the flow of various types of fluids such as water, steam, oil, gas, mud, various corrosive media, liquid metals, and radioactive fluids. The valve's working pressure can range from 0.0013 MPa to 1000 MPa ultra-high pressure, working temperature From -269 °C ultra-low temperature to 1430 °C high temperature. The control of the valve can use a variety of transmission methods, such as manual, electric, hydraulic, pneumatic, worm gear, electromagnetic, electro-hydraulic, electro-hydraulic, gas-liquid, spur, bevel gear drive, etc.; can be in pressure, temperature Or other forms of sensory signals, operate according to predetermined requirements, or simply open or close without relying on the sensing signal, the valve relies on a drive or an automatic mechanism to make the opening and closing parts go up, down, slip, swing or turn Movement, thereby changing the size of its flow area to achieve its control function.
Classification of valves
1. Classified by role and purpose
(1) Cut-off valve: Cut-off valve is also called closed-circuit valve. Its role is to connect or cut off the medium in the pipeline. Cut-off valves include gate valves , globe valves , plug valves, ball valves , butterfly valves , and diaphragm valves.
(2) Check valve : Check valve, also known as check valve or check valve , its role is to prevent the media back in the pipeline. The bottom valve of the pump is also a check valve .
(3) Safety valve : The function of the safety valve is to prevent the medium pressure in the pipe or device from exceeding the specified value, so as to achieve the purpose of safety protection.
(4) Regulating valves: Regulating valves include regulating valves, throttle valves and pressure reducing valves. Their role is to regulate the pressure, flow rate and other parameters of the medium.
(5) Diverter valve: The diverter valve class includes various distribution valves, traps, etc. The role of the diverter valve is to distribute, separate or mix the media in the line.
(6) Exhaust valve: The exhaust valve is an indispensable auxiliary component in the piping system and is widely used in boilers, air conditioners, oil and gas, and water supply and drainage pipes. It is often installed at high points or elbows, eliminates excess gas in pipelines, improves the efficiency of pipeline usage, and reduces energy consumption.
2. Classification by nominal pressure
(1) Vacuum valve: refers to a valve whose working pressure is lower than standard atmospheric pressure.
(2) Low pressure valve: refers to the valve with nominal pressure PN ≤ 1.6Mpa.
(3) Medium pressure valve: refers to a valve with a nominal pressure of PN of 2.5, 4.0, and 6.4 MPa.
(4) High pressure valve: refers to the valve with the working pressure PN of 10~80Mpa.
(5) Ultra-high pressure valve: refers to the valve with nominal pressure PN≥100Mpa.
3. Classified by working temperature
(1) Ultra-low temperature valve: Valve used for medium working temperature t<-100°C.
(2) Cryogenic valve: Valve used for medium operating temperature -100°C≤t≤-40°C.
(3) Normal temperature valve: It is used for valves with medium working temperature -40°C≤t≤120°C.
(4) Medium Temperature Valve: Used for Medium Operating Temperature 120°C
(5) High temperature valve: used for valves with medium operating temperature t>450°C.
4. Classified by driving method
(1) Automatic valves are valves that do not require external force to drive, but rely on the media's own energy to actuate the valve. Such as safety valves, pressure relief valves, traps, check valves, automatic control valves.
(2) Power Actuated Valve: The power actuated valve can be driven by various power sources.
Electric valve: With the help of electrically driven valves.
Pneumatic valves: Valves driven by compressed air.
Hydraulic valve: Valve driven by liquid pressure, such as oil.
In addition there are several combinations of driving methods such as gas-electric valves.
(3) Manual valve: The manual valve uses the handwheel, handle, lever, and sprocket to maneuver the valve. When the valve opening and closing torque is large, this wheel or worm gear reducer can be set between the hand wheel and the valve stem. When necessary, it is also possible to use a universal joint and a transmission shaft for long-distance operation.
5. Classified by nominal diameter
(1) Small diameter valve: Valve with nominal diameter DN ≤ 40mm.
(2) Medium-diameter valves: Valves with a nominal diameter DN of 50 to 300mm.
(3) Large-diameter valves: Valves with a nominal valve DN of 350 to 1200 mm.
(4) Large diameter valve: Valve with nominal diameter DN ≥ 1400mm.
6. Classified by structural features
(1) Sectional valve: The closure moves along the center of the valve seat;
(2) Plug Valve: The closing member is a plunger or ball, rotating around its own centerline;
(3) Gate shape: the closure moves along the center of the vertical seat;
(4) Swing valve: the closing member rotates around the axis outside the valve seat;
(5) Butterfly valve: The disc of the closing member rotates around the axis in the valve seat;
(6) Slide valve: The closing member slides in the direction perpendicular to the passage.
7. Classified by connection method
(1) Threaded valves: The valve body has internal or external threads and is threadedly connected to the pipe.
(2) Flange connection valve: The valve body has a flange and is connected with the pipe flange.
(3) Welding connection valve: The valve body has a welding groove and is welded to the pipe.
(4) Clamp connection valve: The valve body has a clamp and is connected to the pipe clamp.
(5) Sleeve connection valve: It is connected with the pipe sleeve.
(6) Coupling valve: The connection form that directly connects the valve and the two pipes together by bolts.
8. According to body material classification
(1) Valves made of metal: Valves 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 valves, Monel alloy valves.
(2) Non-metallic valve: Its valve body and other parts are made of non-metallic materials. Such as plastic valves, ceramic valves, helium valves, FRP valves.
(3) Metal valve body lining valve: The body shape of the valve body is metal, and all the main surfaces in contact with the medium are linings, such as lining rubber valves, lining plastic valves, and lining ceramic valves.
9. Valve model layout
The valve model should generally indicate the valve type, drive method, connection type, structural characteristics, sealing surface material, valve body material, and nominal pressure. The standardization of the valve model provides convenience for the design, selection and sale of the valve. With more and more types and materials of valves today, the number of valve models is becoming more and more complicated. Although China has a unified standard for the valve model, it is increasingly unable to adapt to the needs of the valve industry. At present, the valve manufacturer generally adopts the unified numbering method; where the method of uniform numbering cannot be adopted, each manufacturer will formulate the numbering method according to his own needs.
"Valve model preparation method" applies to industrial pipeline gate valves , throttle valves, ball valves , butterfly valves, diaphragm valves, plunger valves, plug valves, check valves , safety valves, pressure reducing valves, and traps. It includes the model numbering of valves and the naming of valves .
Valves have a wide range of uses, a wide variety of types, and a large number of classification methods. The total can be divided into two categories:
The first automatic valve: rely on a medium (liquid, gas) and the ability of self-operation itself valves. Such as check valves , safety valves, regulating valves, traps, pressure reducing valves, etc.
The second type of drive valve : The valve that operates by manual, electric, hydraulic, pneumatic . Such as gate valves , globe valves , throttle valves, butterfly valves, ball valves , plug valves , etc.
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