612 A ShenHui Building XIXIAN Road Baoan District Shenzhen 518000 Guangdong China
center sealing butterfly valve, single eccentric sealing butterfly valve, double eccentric sealing butterfly valve, triple eccentric sealing butterfly valve.
① Soft sealing butterfly valve, its sealing pair is composed of non-metal soft material to non-metal soft material and metal hard material to non-metal soft material.
② Metal hard seal butterfly valve, its sealing pair is composed of metal hard material to metal hard material.
①The sealing butterfly valve is divided into a forced sealing butterfly valve and an elastic sealed butterfly valve. Valve with a valve plate extruding the valve seat against the sealing surface or the boxed cantilevered valve body structure will be developed when subjected to the specific pressure sealing; external torque on several occasion, it is possible to generate an adjustable rotation and applied rotational force, thus generating torque in effect. moment is generated.
② Pressure sealed butterfly valve, by the elasticity of the sealing element of its valuve seat or valuve plate produces a specific pressure seal.
③ Automatic sealing butterfly valve, the seal load generated by medium pressure自.
4) According to butterfly valve working pressure:
① Vacuum butterfly valve, a butterfly valve whose working pressure is lower than the standard atmospheric pressure.
② Low-pressure butterfly valve, butterfly valve with nominal pressure ≤ PN16.
③Medium pressure butterfly valve, butterfly valve with nominal pressure PN25~PN63.
④High pressure butterfly valve. Butterfly valve with nominal pressure PN100 ~ PN800.
①High temperature butterfly valve, butterfly valve with t>450℃.
②Medium temperature butterfly valve, 120℃ <t≤450℃ butterfly valve.
③Normal temperature butterfly valve, high quality butterfly valve.
④ Low temperature butterfly valve, butterfly valve for –100℃<t<-29℃.
⑤Ultra-low temperature butterfly valve, t≤-100℃ butterfly valve.
wafer butterfly valve, flange butterfly valve, lug butterfly valve, welded butterfly valve.
The sealing principle is to ensure that the sealing surface has a suitable surface roughness value when the valve plate is processed, and the synthetic rubber valve seat forms a suitable surface roughness value for the sealing surface during molding. When the valve is closed, through the rotation of the valve plate, the outer circular sealing surface of the valve plate squeezes the synthetic rubber valve seat, causing the synthetic rubber valve seat to elastically deform and form an elastic force as a sealing specific pressure to ensure the sealing of the valve.
The sealing structure uses polytetrafluoroethylene and synthetic rubber to form a composite valve seat. Its characteristic is that the elasticity of the valve seat is still provided by synthetic rubber and the use of polytetrafluoroethylene's low friction coefficient, resistance to wear and aging, and the use of polytetrafluoroethylene as the valve seat sealing surface material improves the life of the butterfly valve.
The rotation center of the valve plate (i.e., the center of the valve shaft) is located on the center line of the valve body, and forms an a-dimensional offset from the sealing section of the valve plate.
Since the rotation center of the valve plate (i.e., the center of the valve shaft) and the sealing section of the valve plate are set eccentrically according to a, the se
aling surfaces on the valve plate and the valve seat form a complete circle, so it is easier to ensure that the valve plate and the valve seat are aligned during processing. Surface roughness value of sealing surface.
When the single eccentric seal butterfly valve is in a fully open state, its valve plate sealing surface will completely separate from the valve seat sealing surface, forming a gap x between the valve plate sealing surface and the valve seat sealing surface. The valve plate of this type of butterfly valve ranges from 0°~ When opening at 90°, the sealing surface of the valve plate will gradually separate from the sealing surface of the valve seat. In the usual design, when the valve plate rotates from 0° to 20°~25°, the sealing surface of the valve plate can completely separate from the sealing surface of the valve seat, so that during the opening and closing process of the butterfly valve, the sealing surfaces of the valve plate and the valve seat are opposite to each other. Mechanical wear and extrusion are greatly reduced, and the sealing performance of the butterfly valve is improved.
When the butterfly valve is closed, through the rotation of the valve plate, the outer circular sealing surface of the valve plate gradually approaches and squeezes the PTFE valve seat, causing the PTFE valve seat to elastically deform and form an elastic force as a sealing ratio to ensure the butterfly valve of seal.
The composite valve seat is composed of polytetrafluoroethylene and synthetic rubber. Its characteristic is that the elasticity of the valve seat is still provided by synthetic rubber and the use of polytetrafluoroethylene's low friction coefficient, resistance to wear and aging, and the use of polytetrafluoroethylene as the valve seat sealing surface material improves the life of the butterfly valve. .
The Z-shaped cross-section PTFE valve seat is used. When the butterfly valve is closed, the medium pressure acts on the valve seat, and the medium pressure generates a certain sealing ratio between the sealing surfaces, helping the sealing pair to seal better. The sealing structure shown in Figure 3-62 uses stainless steel metal to seal the valve seat, so that the butterfly valve can be used under high temperature conditions.
① During the opening and closing process of the butterfly valve, when the valve plate rotates and squeezes the elastic soft valve seat, mechanical wear and scratches will occur on the valve plate and valve seat;
② After the valve plate squeezes the elastic valve seat, the elastic valve seat or the elastic layer of the valve plate will produce permanent plastic deformation, cold flow, elastic failure, etc.;
③The material of the elastic valve seat or the elastic layer of the valve plate ages and fails;
④Medium cavitation and erosion of the sealing surface.
①The structure is more complex than the Chinese sealed butterfly valve and the cost is slightly higher;
②The sealing performance is better than that of the centerline sealing butterfly valve;
③The service life is longer than that of Chinese sealed butterfly valves, and the operating pressure is also higher.
Butterfly valves are suitable for flow regulation. Since the pressure loss of butterfly valves in the pipeline is relatively large, about three times that of gate valves, when selecting butterfly valves, the impact of pressure loss on the pipeline system should be fully considered. The strength of the butterfly plate to withstand the pressure of the pipeline medium when closed should also be considered. sex. In addition, the operating temperature limitations of the elastomeric seat material at elevated temperatures must also be considered. The structural length and overall height of the butterfly valve are small, the opening and closing speed is fast, and it has good fluid control characteristics.
The structural principle of the butterfly valve is most suitable for making large-diameter valves. When a butterfly valve is required to control flow, the most important thing is to correctly select the size and type of butterfly valve so that it can work properly and effectively. Generally, in throttling, regulating control and mud media, short structural length and fast opening and closing speed (1/4r) are required. For low pressure cutoff (small pressure difference), butterfly valve is recommended. Butterfly valves can be used when there are two-position adjustment, narrowing channels, low noise, cavitation and vaporization phenomena, a small amount of leakage into the atmosphere, and abrasive media. When throttling adjustment is required under special working conditions, strict sealing is required, or butterfly valves are used under severe wear, low temperature (cryogenic) and other working conditions, a specially designed triple eccentric or double eccentric valve with a specially designed metal sealing belt adjustment device is required. butterfly valve.
The center line butterfly valve is suitable for fresh water, sewage, sea water, salt water, steam, natural gas, food, medicine, oil and various products that require complete sealing, zero gas test leakage, high life requirements, and an operating temperature of -10~150°C. Acid-base and other pipelines. Soft-sealed eccentric butterfly valves are suitable for bidirectional opening, closing and adjustment of ventilation and dust removal pipelines. They are widely used in gas pipelines and waterways in metallurgy, light industry, electric power, and petrochemical systems.
Metal-to-metal wire sealed double eccentric butterfly valve is suitable for urban heating, steam supply, water supply, gas, oil, acid and alkali and other pipelines, as a regulating and intercepting device. In addition to being used as a program control valve for large-scale pressure swing adsorption (PSA) gas separation devices, metal-to-metal surface sealed triple eccentric butterfly valves can also be widely used in petroleum, petrochemical, chemical, metallurgy, electric power and other fields. They are ideal for gate valves, globe valves, etc. Good alternative product.
1) Since butterfly valves have a relatively large pressure loss compared to gate valves and ball valves, they are suitable for pipeline systems with loose pressure loss requirements.
2) Since the butterfly valve can be used for flow regulation, it is suitable to be used in pipelines that require flow regulation.
3) Due to the limitations of the structure and sealing material of the butterfly valve, it is not suitable for use in high temperature and high pressure pipeline systems. The general working temperature is below 300℃, and the nominal pressure is below PN40.
4) Since the butterfly valve has a relatively short structural length and can be made into a large diameter, butterfly valves should be selected when the structural length is short or for large diameter valves (such as DN1000 or above).
5) Since the butterfly valve can be opened or closed by only rotating 90°, it is appropriate to choose a butterfly valve in situations where fast opening and closing are required.
