A butterfly valve is a type of valve that uses a round butterfly plate as an opening and closing element and opens, closes, and regulates a fluid passage as the valve stem rotates. The butterfly plate of the butterfly valve is installed in the diameter direction of the pipe. In the butterfly valve body cylindrical passage, the disc-shaped butterfly plate rotates around the axis, the rotation angle is between 0° and 90°, and when the valve rotates to 90°, the valve is fully opened.
The history of butterfly valve development
In the 30's, the United States invented the butterfly valve. It was introduced to Japan in the 1950s. It was generally adopted in Japan in the 1960s, and promotion in China was after the 1970s. At present, in the world, butterfly valves with DN300 mm or more have gradually replaced gate valves. Compared with the gate valve, the butterfly valve has a short opening and closing time, a small operation, a small installation space and a light weight. Taking DN1000 as an example, the butterfly valve is about 2T and the gate valve is about 3.5T. The butterfly valve is easy to be combined with various driving devices and has good durability and reliability. The disadvantage of the rubber seal butterfly valve is that if it is used for throttling, cavitation may occur due to improper use, and the rubber seat may peel off or be damaged. For this reason, the metal seal butterfly valve is now being developed internationally, and the cavitation area is reduced. In recent years, China has also developed a metal seal butterfly valve. In recent years, Japan has also developed a comb-shaped butterfly valve that is resistant to cavitation erosion, low vibration, and low noise.
Generally the life of the seal seat is under normal conditions, rubber 15 years - 20 years, metal 80 years - 90 years. However, how to use it correctly must be based on working conditions.
The relationship between the opening and the flow of the butterfly valve is basically a linear proportional change. If it is used to control the flow, its flow characteristics are also closely related to the flow resistance of the piping. If the diameters and forms of the two pipeline installation valves are the same, and the pipeline loss coefficient is different, the flow difference of the valves will also be very large.
If the valve is in a large throttling state, the back of the valve plate is prone to cavitation and may damage the valve. Generally, it is used outside 15°.
When the butterfly valve is in the middle opening degree, the shape of the opening formed by the front end of the valve body and the butterfly plate is centered on the valve shaft, and the two sides form different states. The front end of the butterfly plate moves in the direction of the flowing water and the other side flows in the direction of the flowing water. Moving, therefore, one side of the valve body and the valve plate form a nozzle-like opening, the other side similar to the orifice-shaped opening, the nozzle side faster than the throttle side of the flow rate, and the throttle valve will produce negative pressure, often Rubber seals will come off.
The butterfly valve and the butterfly rod itself have no self-locking ability. In order to position the butterfly plate, a worm gear reducer is added to the valve stem. The use of a worm gear reducer not only allows the butterfly plate to have self-locking capability, allows the butterfly plate to stop at any position, but also improves the valve's operating performance.
Butterfly valve operating torque, due to opening and valve opening and closing direction of different values, horizontal butterfly valve, especially large-diameter valve, due to water depth, the shaft shaft, the head of the water generated by the torque can not be ignored. In addition, when the elbow of the inlet side of the valve is deflected, the bias flow will increase and the torque will increase. When the valve is in the middle opening, the operating mechanism needs to be self-locking due to the effect of the water flow torque.
The butterfly valve is simple in structure and consists of only a few parts. It consumes less material. It is small in size, light in weight, small in installation size, small in driving torque, and easy to operate. It can be quickly opened and closed by simply rotating 90°. With good flow regulation and close sealing, the butterfly valve is the dominant valve type in the field of medium and low pressure, medium and low pressure. When the butterfly valve is in the fully open position, the thickness of the butterfly plate is the only resistance when the medium flows through the valve body, so the pressure drop generated by the valve is very small, so it has better flow control characteristics. The butterfly valve has two types of seals: elastic seal and metal seal. Elastic sealing valve, sealing ring can be mounted on the valve body or attached around the butterfly board. Valves that use metal seals generally have longer life than elastomer-sealed valves, but they are difficult to completely seal. Metal seals can accommodate higher operating temperatures, while elastomeric seals have temperature-restricted defects. If the butterfly valve is required to be used as a flow control, the main thing is to choose the correct size and type of valve. The structural principle of the butterfly valve is particularly suitable for making large-diameter valves. Butterfly valves are widely used not only in general industries such as petroleum, gas, chemical and water treatment, but also in cooling water systems of thermal power plants. Commonly used butterfly valves have two kinds of clip-on butterfly valves and flange-type butterfly valves. The clip-on butterfly valve uses a stud bolt to connect the valve between the two pipe flanges. The flanged butterfly valve has a flange on the valve. The upper flanges of the valve are connected to the pipe flange by bolts. The strength performance of a valve is the ability of the valve to withstand medium pressure. The valve is a mechanical product that withstands internal pressure and therefore must have sufficient strength and rigidity to ensure long-term use without rupture or deformation.
With the application of antiseptic synthetic rubber and PTFE, the performance of the butterfly valve is improved and it is satisfied with different working conditions. In the past ten years, metal sealing butterfly valves have developed rapidly. With the application of high temperature resistance, low temperature resistance, strong corrosion resistance, strong erosion resistance, and high strength alloy materials in butterfly valves, the metal sealing butterfly valves are exposed to high temperatures, low temperatures, and strong erosion. It has been widely used in other conditions and has partially replaced the globe valve, gate valve and ball valve.
The structural characteristics of the butterfly valve has a simple structure, small size, light weight, material consumption, small installation size, rapid switching, 90 reciprocating rotation, small drive torque characteristics, used to cut off, connect, adjust the pipeline Medium, with good fluid control properties and closed sealing properties.
The butterfly valve can carry mud, with minimal liquid accumulation at the mouth of the pipe. At low pressure, a good seal can be achieved. Good adjustment performance.
The streamlined design of the butterfly plate, so that the loss of fluid resistance is small, can be described as an energy-saving products.
The valve stem is a through-rod structure. After quenching and tempering, it has good comprehensive mechanical properties, corrosion resistance, and scratch resistance. When the butterfly valve is opened and closed, the valve stem only performs rotary motion without lifting operation. The packing of the valve stem is not easy to damage, and the seal is reliable. The utility model is fixed with a butterfly taper pin, and the outstretched end is of an anti-bump type design, so as to prevent the valve stem from collapsing when the stem and the butterfly plate are accidentally broken.
Connections are flanged, clip-on, butt-welded, and lug-to-clip connections.
Drive forms include manual, worm gear, electric, pneumatic, hydraulic, electro-hydraulic linkages and other actuators that enable remote control and automation. The disadvantages of butterfly valves are as follows:
1, the use of pressure and operating temperature range is small.
2, poor sealing.
The history of butterfly valve development
In the 30's, the United States invented the butterfly valve. It was introduced to Japan in the 1950s. It was generally adopted in Japan in the 1960s, and promotion in China was after the 1970s. At present, in the world, butterfly valves with DN300 mm or more have gradually replaced gate valves. Compared with the gate valve, the butterfly valve has a short opening and closing time, a small operation, a small installation space and a light weight. Taking DN1000 as an example, the butterfly valve is about 2T and the gate valve is about 3.5T. The butterfly valve is easy to be combined with various driving devices and has good durability and reliability. The disadvantage of the rubber seal butterfly valve is that if it is used for throttling, cavitation may occur due to improper use, and the rubber seat may peel off or be damaged. For this reason, the metal seal butterfly valve is now being developed internationally, and the cavitation area is reduced. In recent years, China has also developed a metal seal butterfly valve. In recent years, Japan has also developed a comb-shaped butterfly valve that is resistant to cavitation erosion, low vibration, and low noise.
Generally the life of the seal seat is under normal conditions, rubber 15 years - 20 years, metal 80 years - 90 years. However, how to use it correctly must be based on working conditions.
The relationship between the opening and the flow of the butterfly valve is basically a linear proportional change. If it is used to control the flow, its flow characteristics are also closely related to the flow resistance of the piping. If the diameters and forms of the two pipeline installation valves are the same, and the pipeline loss coefficient is different, the flow difference of the valves will also be very large.
If the valve is in a large throttling state, the back of the valve plate is prone to cavitation and may damage the valve. Generally, it is used outside 15°.
When the butterfly valve is in the middle opening degree, the shape of the opening formed by the front end of the valve body and the butterfly plate is centered on the valve shaft, and the two sides form different states. The front end of the butterfly plate moves in the direction of the flowing water and the other side flows in the direction of the flowing water. Moving, therefore, one side of the valve body and the valve plate form a nozzle-like opening, the other side similar to the orifice-shaped opening, the nozzle side faster than the throttle side of the flow rate, and the throttle valve will produce negative pressure, often Rubber seals will come off.
The butterfly valve and the butterfly rod itself have no self-locking ability. In order to position the butterfly plate, a worm gear reducer is added to the valve stem. The use of a worm gear reducer not only allows the butterfly plate to have self-locking capability, allows the butterfly plate to stop at any position, but also improves the valve's operating performance.
Butterfly valve operating torque, due to opening and valve opening and closing direction of different values, horizontal butterfly valve, especially large-diameter valve, due to water depth, the shaft shaft, the head of the water generated by the torque can not be ignored. In addition, when the elbow of the inlet side of the valve is deflected, the bias flow will increase and the torque will increase. When the valve is in the middle opening, the operating mechanism needs to be self-locking due to the effect of the water flow torque.
The butterfly valve is simple in structure and consists of only a few parts. It consumes less material. It is small in size, light in weight, small in installation size, small in driving torque, and easy to operate. It can be quickly opened and closed by simply rotating 90°. With good flow regulation and close sealing, the butterfly valve is the dominant valve type in the field of medium and low pressure, medium and low pressure. When the butterfly valve is in the fully open position, the thickness of the butterfly plate is the only resistance when the medium flows through the valve body, so the pressure drop generated by the valve is very small, so it has better flow control characteristics. The butterfly valve has two types of seals: elastic seal and metal seal. Elastic sealing valve, sealing ring can be mounted on the valve body or attached around the butterfly board. Valves that use metal seals generally have longer life than elastomer-sealed valves, but they are difficult to completely seal. Metal seals can accommodate higher operating temperatures, while elastomeric seals have temperature-restricted defects. If the butterfly valve is required to be used as a flow control, the main thing is to choose the correct size and type of valve. The structural principle of the butterfly valve is particularly suitable for making large-diameter valves. Butterfly valves are widely used not only in general industries such as petroleum, gas, chemical and water treatment, but also in cooling water systems of thermal power plants. Commonly used butterfly valves have two kinds of clip-on butterfly valves and flange-type butterfly valves. The clip-on butterfly valve uses a stud bolt to connect the valve between the two pipe flanges. The flanged butterfly valve has a flange on the valve. The upper flanges of the valve are connected to the pipe flange by bolts. The strength performance of a valve is the ability of the valve to withstand medium pressure. The valve is a mechanical product that withstands internal pressure and therefore must have sufficient strength and rigidity to ensure long-term use without rupture or deformation.
With the application of antiseptic synthetic rubber and PTFE, the performance of the butterfly valve is improved and it is satisfied with different working conditions. In the past ten years, metal sealing butterfly valves have developed rapidly. With the application of high temperature resistance, low temperature resistance, strong corrosion resistance, strong erosion resistance, and high strength alloy materials in butterfly valves, the metal sealing butterfly valves are exposed to high temperatures, low temperatures, and strong erosion. It has been widely used in other conditions and has partially replaced the globe valve, gate valve and ball valve.
The structural characteristics of the butterfly valve has a simple structure, small size, light weight, material consumption, small installation size, rapid switching, 90 reciprocating rotation, small drive torque characteristics, used to cut off, connect, adjust the pipeline Medium, with good fluid control properties and closed sealing properties.
The butterfly valve can carry mud, with minimal liquid accumulation at the mouth of the pipe. At low pressure, a good seal can be achieved. Good adjustment performance.
The streamlined design of the butterfly plate, so that the loss of fluid resistance is small, can be described as an energy-saving products.
The valve stem is a through-rod structure. After quenching and tempering, it has good comprehensive mechanical properties, corrosion resistance, and scratch resistance. When the butterfly valve is opened and closed, the valve stem only performs rotary motion without lifting operation. The packing of the valve stem is not easy to damage, and the seal is reliable. The utility model is fixed with a butterfly taper pin, and the outstretched end is of an anti-bump type design, so as to prevent the valve stem from collapsing when the stem and the butterfly plate are accidentally broken.
Connections are flanged, clip-on, butt-welded, and lug-to-clip connections.
Drive forms include manual, worm gear, electric, pneumatic, hydraulic, electro-hydraulic linkages and other actuators that enable remote control and automation. The disadvantages of butterfly valves are as follows:
1, the use of pressure and operating temperature range is small.
2, poor sealing.
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1 Excellent high temperature stability and integrity of masonry
2 Good resistance to thermal shock stability
3 Good mechanical erosion and wear resistance
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