①The structure of the center line butterfly valve The center line sealing butterfly valve is that the entire butterfly plate and the valve seat are concentric within 360° of the circle, with two-way sealing performance, and the flow rate can be adjusted freely. Most of the centerline butterfly valves are of an interference seal type, that is, a rubber liner is inserted on the valve seat of the valve body. If the medium is more corrosive, PTFE can be suppressed, and rubber is lined on the back of the PTFE to increase resilience. The ballast ring can be replaced, it can also be glued to the valve body, and the ballast ring can be placed on the butterfly plate. The flange surface of the rubber liner is also a seal to the pipe flange. If a rubber gasket is added between the two flange surfaces when installing this valve, it will affect the sealing performance of the rubber ring.Bronze Gate Valve gate valve manufacturersTherefore, it is not necessary Superfluously. Since the centerline sealing butterfly valve is an interference mandatory sealing form, the applicable pressure is limited, and it is usually used under working conditions not greater than PN10. But for water supply and drainage pipes, this is enough.
②Eccentric butterfly valve structure The general butterfly valve has a single eccentric or double eccentric structure. The purpose of eccentricity is to separate the valve seat and the sealing surface after the butterfly plate is opened to about 20°, thereby reducing friction. The double eccentric structure is designed to deviate the shaft from the center line of the sealing surface to form a first eccentricity; the shaft slightly deviates from the center line of the pipeline to form a second eccentricity. The purpose of these two eccentricities is to reduce the friction between the valve seat and the sealing ring during the valve switching stroke.
The triple eccentric metal sealing butterfly valve adds an eccentric angle β on the basis of double eccentricity, which not only utilizes the original cam effect, but also completely eliminates the friction between the valve seat and the sealing ring during the 90° stroke. The first eccentric shaft deviates from the centerline a of the sealing surface. Butterfly valves designed and manufactured according to this principle are usually called single-sided eccentric butterfly valves. The second eccentric—the shaft slightly deviates from the pipeline and the valve centerline b, and the butterfly valve designed and manufactured according to the principle of one eccentricity and two eccentricity is usually called a double eccentric butterfly valve.
The third eccentric ——The triple eccentric structure has one more eccentric angleβ than the double eccentric structure, and the sealing surface of the butterfly plate adopts an eccentric cone. From the geometric shape, the butterfly plate and the sealing ring are completely separated in the whole switching stroke of the valve. This unique eccentric combination not only makes use of the cam effect, but also completely eliminates friction, so that during the 90° stroke of the valve, there is no friction between the butterfly plate and the seat sealing ring, eliminating the problem of wear and leakage. The triple eccentric metal sealing butterfly valve optimizes the contact characteristics between the butterfly plate and the seat sealing ring. The contact angle of most butterfly valves is 3°～12.5°, this range is the lock taper range, which will produce high sealing torque and opening torque. The contact angle of the sealing surface of the triple eccentric metal seal butterfly valve is greater than the locking taper range, which eliminates the possibility of jamming from the geometric shape, thereby ensuring that the torque required for valve switching will not change greatly during the valve's entire service life.
Features of butterfly valve
①Compared with other valves of the same specification and same pressure level, the butterfly valve has short structure length, small size, light weight and simple structure.
②Quick opening and closing, easy operation, can be used as a fast opening and closing valve.
③It has good flow adjustment function and closed sealing performance, long service life, and can be used as a regulating valve.
④It is suitable for large-diameter valves and is widely used in large-scale water supply and drainage pipelines.