Soft-sealing double eccentric flanged butterfly valve 2

The sealing principle of double eccentric sealing butterfly valve:

Due to the double eccentric butterfly valve, the center of rotation of the butterfly plate (that is, the center of the valve shaft) and the centerline of the valve body form a dimension b offset on the basis of the single eccentric butterfly valve, so that during the opening process of the butterfly valve, the sealing surface of the butterfly plate will be larger than that of the single eccentric sealing butterfly valve. Get away from the sealing surface of the valve seat faster. When the butterfly plate rotates to 8°-12°, the sealing surface of the butterfly plate is completely separated from the sealing surface of the valve seat. When fully opened, a larger gap Y is formed between the two sealing surfaces. The design of this type of butterfly valve greatly reduces the mechanical damage and extrusion deformation between the two sealing surfaces, and improves the sealing performance of the butterfly valve.

Its structural feature is that the shaft center of the valve stem is not only eccentric to the center of the butterfly plate, but also deviates from the center of the body. The effect of double eccentricity makes the butterfly plate break away from the valve seat immediately after the valve is opened, which greatly eliminates the unnecessary excessive extrusion and scraping between the butterfly plate and the valve seat, reduces the opening resistance distance, reduces wear, and improves the sealing performance. The life of the valve seat is greatly reduced, and the scratch is greatly reduced. At the same time, the double eccentric butterfly valve can also use the metal valve seat, which improves the application of the butterfly valve in the high temperature field. However, because its sealing principle is a position sealing structure, that is, the sealing surface of the butterfly plate and the valve seat is in line contact, and the elastic deformation caused by the extrusion of the valve seat by the butterfly plate produces a sealing effect, so the requirements for the closing position are very high (especially for metal valves). Valve seat), low pressure bearing capacity, which is why traditionally people think that butterfly valves are not resistant to high pressure and have large leakage.

Main external dimensions and connection dimensions：