Classification of butterfly valves
The opening and closing parts are disc-shaped discs and can rotate around the axis of the valve body. It is mainly composed of valve body, valve stem, disc and sealing ring. The valve body is cylindrical, short in axial length, and has a built-in disc. The disc is driven by the valve stem, and if it is turned 90°, it can open and close once. By changing the deflection angle of the disc, the flow of the medium can be controlled. The main seal is a sealing ring, and the material is used according to the purpose and medium. The commonly used butterfly valves include wafer butterfly valves and flange butterfly valves. Wafer type butterfly valve uses double-head bolts to connect the valve between two pipe flanges. Flange type butterfly valve has flanges on the valve, and bolts are used to connect the flanges at both ends of the valve to the pipe flanges.
1.Classified by structure
(1) Center sealing butterfly valve
(2) Single eccentric sealing butterfly valve
(3) Double eccentric sealing butterfly valve
(4) Triple eccentric sealing butterfly valve
2.Classified by sealing surface material
(1) Soft sealing butterfly valve.
①The sealing pair is composed of non-metallic soft material to non-metallic soft material.
② The sealing pair is composed of metallic hard materials and non-metallic soft materials.
(2) Metal hard seal butterfly valve. The sealing pair is composed of a metal hard material to a metal hard material.
3.Classified by sealing form
(1) Forced sealing butterfly valve
①Elastic sealing butterfly valve. The specific sealing pressure is generated by the elasticity of the valve seat or the valve plate when the valve plate squeezes the valve seat when the valve is closed.
② External torque sealing butterfly valve. The seal specific pressure is generated by the torque applied to the valve shaft.
(2) Pressurized sealing butterfly valve. The sealing specific pressure is generated by the pressure of the elastic sealing element on the valve seat or valve plate.
(3) Automatic sealing butterfly valve. The sealing specific pressure is automatically generated by the medium pressure.
4.Classified by work pressure
(1) Vacuum butterfly valve. Butterfly valves whose working pressure is lower than the atmospheric pressure of the standard reactor.
(2) Low-pressure butterfly valve. Butterfly valve with nominal pressure PN<1.6MPa.
(3) Medium pressure butterfly valve. Butterfly valve with nominal pressure PN of 2.5~6.4MPa.
(4) High-pressure butterfly valve. Butterfly valve with nominal pressure PN of 10.0~80.0MPa.
(5) Ultra-high pressure butterfly valve. Butterfly valve with nominal pressure PN>100MPa.
5.Classified by working temperature
(1) High temperature butterfly valve. t>450℃ butterfly valve
(2) Medium temperature butterfly valve. Butterfly valve with 120℃<t<450℃.
(3) Normal temperature butterfly valve. -40℃<t<120℃ butterfly valve.
(4) Low temperature butterfly valve. -100℃<t<-40℃ butterfly valve.
(5) Ultra-low temperature butterfly valve. Butterfly valve with t<-100℃.
6.Classified by connection method
(1) Wafer butterfly valve.
The butterfly plate of the wafer butterfly valve is installed in the diameter direction of the pipeline. In the cylindrical passage of the butterfly valve body, the disc-shaped butterfly plate rotates around the axis, and the rotation angle is between 0° and 90°. When the rotation reaches 90°, the valve is fully opened.
The wafer butterfly valve is simple in structure, small in size and light in weight, and consists of only a few parts. Moreover, it can be opened and closed quickly by rotating 90°, and the operation is simple. At the same time, the valve has good fluid control characteristics. 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 small, so it has better flow control characteristics. The butterfly valve has two sealing types: elastic seal and metal seal. Elastic sealing valve, the sealing ring can be inlaid on the valve body or attached to the periphery of the butterfly plate.
2) Flanged butterfly valve.
The flange type butterfly valve is a vertical plate structure, and the valve stem is an integral metal hard seal. The sealing ring of the valve is a composite structure of flexible graphite plate and stainless steel plate. It is installed on the valve body, and the sealing surface of the butterfly plate is welded with stainless steel. The sealing ring of the soft sealing valve is made of nitrile rubber and is installed on the butterfly plate.
(3) Lug butterfly valve.
(4) Welded butterfly valve.
Welded butterfly valve is a non-closed butterfly valve, which is widely used in the production process of building materials, metallurgy, mining, electric power and other production processes on pipelines with a medium temperature of ≤300℃ and a nominal pressure of 0.1Mpa for connection, opening and closing.
Or adjust the amount of media.
Butterfly valves can be divided into offset plate type, vertical plate type, inclined plate type and lever type according to the structure. According to the sealing form, it can be divided into two types: soft sealing type and hard sealing type. The soft seal type generally uses a rubber ring seal, and the hard seal type usually uses a metal ring seal.
According to the connection type, it can be divided into flange connection and wafer connection; according to the transmission mode, it can be divided into manual, gear transmission, pneumatic, hydraulic and electric.
The industrial butterfly valve is characterized by high temperature resistance and high applicable pressure range. The valve has a large nominal diameter, the valve body is made of carbon steel, and the sealing ring of the valve plate uses a metal ring instead of a rubber ring. The large high temperature butterfly valve is made of steel plate welding, and is mainly used for flue ducts and gas pipes of high temperature media.
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