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The role and use of the valve

  • Time of issue:2021-08-13

The role and use of the valve

(Summary description)　The valve is an accessory of the pipeline, used to control the flow, pressure, and direction of the fluid. The fluid to be controlled can be liquid, gas, gas-liquid mixture or solid-liquid mixture.

  one. Basic parameters of valve

　　The basic parameters of the valve include working pressure (PN), working temperature (T) and nominal diameter (DN). For various valves equipped on pipelines, nominal pressure and nominal diameter are commonly used as basic parameters. Nominal pressure refers to the maximum working pressure that a valve of a certain material can withstand at a specified temperature. The nominal diameter refers to the nominal inner diameter of the connecting end of the valve body and the pipeline. Valves, pipelines and pipeline accessories of the same nominal diameter can be connected to each other, which is interchangeable.

  two. Valve classification

　　 1. According to function and purpose

　　 According to the different functions of the valve, it can be divided into the following five types:

　　①Shutoff valve

　　 shut-off valve is also called closed-circuit valve, its function is to connect or cut off the medium in the pipeline. Block valves include gate valves, globe valves, plug valves, ball valves, butterfly valves, and diaphragm valves.

　　②Check valve

　　 Check valve is also called one-way valve or check valve, its function is to prevent the back flow of the medium in the pipeline. For example, the suction valve of the water pump belongs to the non-return valve category.

　　③Safety valve

　　 The role of safety valves is to prevent the pressure of the medium in the pipeline or device from exceeding the specified value to protect the safe operation of subsequent equipment.

　　④Regulating valve

　　The function of the regulating valve is to regulate the pressure, flow and other parameters of the medium. The regulating valve has different classification methods. According to the purpose and function, the regulating valve can be divided into:

　　 (1) Two-position valve. The two-position valve is mainly used to close or connect the medium.

　　 (2) Regulating valve. The regulating valve is mainly used for regulating the coefficient. When selecting the valve, the flow characteristics of the regulating valve need to be determined; the regulating valve can be divided into the following forms according to the structure: single-seat regulating valve; double-seat regulating valve; sleeve regulating valve; angle regulating Valve; three-way regulating valve; diaphragm valve; butterfly valve; ball valve; eccentric rotary valve.

　　 (3) Shut-off valve. Usually refers to a valve with a leakage rate of less than one part in 100,000.

　　⑤Divert valve

　　 The diverter valve includes various distribution valves and flow valves, etc., whose function is to distribute, separate or mix the medium in the pipeline.

　　2. According to the valve drive mode

　　According to the valve drive mode, it can be divided into the following three types:

　　①Automatic valve

　　 refers to valves that do not require external drive, but rely on the energy of the medium to actuate the valve, such as safety valves, pressure reducing valves, traps, check valves, automatic control valves, etc.

　　②Power driven valve

　　The power-driven valve can be driven by various power sources. Including electric valves driven by electricity, pneumatic valves driven by compressed air, hydraulic valves driven by hydraulic pressure such as oil, and combinations of various driving methods, such as pneumatic-electric valves.

　　③Manual valve

　　Manual valves use handwheels, handles, levers, sprockets and other components to manipulate the valve action by manpower. When the valve closing torque is large, a gear or turbo reducer can be set between the handwheel and the valve stem. If necessary, universal joints and drive shafts can also be used for long-distance operation.

　　3. Press the connection method

　　 can be divided into the following six types according to the connection method:

　　①Threaded connection valve: The valve body has an internal thread or an external thread to connect with the pipe thread;

　　②Flange connection valve: the valve body has a flange to connect with the pipeline flange;

　　③Welding connection valve: The valve body has a welding groove and is welded to the pipeline;

　　④Clamp-connected valve: the valve body has a clamp to connect with the pipe clamp;

　　⑤ Card sleeve connection valve: It is connected with the pipeline by a card sleeve;

　　⑥Wafer connection valve: a connection form in which the valve and the two pipes are directly clamped together with bolts.

　　4. According to the valve body material

　　①Metal material valve

　　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, etc.

　　②Non-metallic valve

　　The valve body and other parts are m

  • Time of issue:2021-08-13
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Information

　The valve is an accessory of the pipeline, used to control the flow, pressure, and direction of the fluid. The fluid to be controlled can be liquid, gas, gas-liquid mixture or solid-liquid mixture.

  one. Basic parameters of valve

　　The basic parameters of the valve include working pressure (PN), working temperature (T) and nominal diameter (DN). For various valves equipped on pipelines, nominal pressure and nominal diameter are commonly used as basic parameters. Nominal pressure refers to the maximum working pressure that a valve of a certain material can withstand at a specified temperature. The nominal diameter refers to the nominal inner diameter of the connecting end of the valve body and the pipeline. Valves, pipelines and pipeline accessories of the same nominal diameter can be connected to each other, which is interchangeable.

  two. Valve classification

　　 1. According to function and purpose

　　 According to the different functions of the valve, it can be divided into the following five types:

　　①Shutoff valve

　　 shut-off valve is also called closed-circuit valve, its function is to connect or cut off the medium in the pipeline. Block valves include gate valves, globe valves, plug valves, ball valves, butterfly valves, and diaphragm valves.

　　②Check valve

　　 Check valve is also called one-way valve or check valve, its function is to prevent the back flow of the medium in the pipeline. For example, the suction valve of the water pump belongs to the non-return valve category.

　　③Safety valve

　　 The role of safety valves is to prevent the pressure of the medium in the pipeline or device from exceeding the specified value to protect the safe operation of subsequent equipment.

　　④Regulating valve

　　The function of the regulating valve is to regulate the pressure, flow and other parameters of the medium. The regulating valve has different classification methods. According to the purpose and function, the regulating valve can be divided into:

　　 (1) Two-position valve. The two-position valve is mainly used to close or connect the medium.

　　 (2) Regulating valve. The regulating valve is mainly used for regulating the coefficient. When selecting the valve, the flow characteristics of the regulating valve need to be determined; the regulating valve can be divided into the following forms according to the structure: single-seat regulating valve; double-seat regulating valve; sleeve regulating valve; angle regulating Valve; three-way regulating valve; diaphragm valve; butterfly valve; ball valve; eccentric rotary valve.

　　 (3) Shut-off valve. Usually refers to a valve with a leakage rate of less than one part in 100,000.

　　⑤Divert valve

　　 The diverter valve includes various distribution valves and flow valves, etc., whose function is to distribute, separate or mix the medium in the pipeline.

　　2. According to the valve drive mode

　　According to the valve drive mode, it can be divided into the following three types:

　　①Automatic valve

　　 refers to valves that do not require external drive, but rely on the energy of the medium to actuate the valve, such as safety valves, pressure reducing valves, traps, check valves, automatic control valves, etc.

　　②Power driven valve

　　The power-driven valve can be driven by various power sources. Including electric valves driven by electricity, pneumatic valves driven by compressed air, hydraulic valves driven by hydraulic pressure such as oil, and combinations of various driving methods, such as pneumatic-electric valves.

　　③Manual valve

　　Manual valves use handwheels, handles, levers, sprockets and other components to manipulate the valve action by manpower. When the valve closing torque is large, a gear or turbo reducer can be set between the handwheel and the valve stem. If necessary, universal joints and drive shafts can also be used for long-distance operation.

　　3. Press the connection method

　　 can be divided into the following six types according to the connection method:

　　①Threaded connection valve: The valve body has an internal thread or an external thread to connect with the pipe thread;

　　②Flange connection valve: the valve body has a flange to connect with the pipeline flange;

　　③Welding connection valve: The valve body has a welding groove and is welded to the pipeline;

　　④Clamp-connected valve: the valve body has a clamp to connect with the pipe clamp;

　　⑤ Card sleeve connection valve: It is connected with the pipeline by a card sleeve;

　　⑥Wafer connection valve: a connection form in which the valve and the two pipes are directly clamped together with bolts.

　　4. According to the valve body material

　　①Metal material valve

　　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, etc.

　　②Non-metallic valve

　　The valve body and other parts are made of non-metallic materials, such as plastic valves, ceramic valves, enamel valves, FRP valves, etc.

　　③Metal valve body lining valve

　　The valve body is made of metal, and the main surfaces in contact with the medium are lined, such as rubber-lined valves, plastic-lined valves, and ceramic-lined valves.

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Next: What is the role of calipers
Previous: The principle and characteristics of the use of flanges
Next: What is the role of calipers

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