In the cylindrical passage of Posi seal butterfly valve, the disc-shaped butterfly plate rotates around the axis and its rotation angle is between 0 ° and 90 °. When the rotation angle is 90 degrees, the automated butterfly valve is fully open. The new type of high life stainless steel butterfly valve will have some problems in the process of use, so it should be installed horizontally in the pipeline. According to the connection mode, the soft seal butterfly valve can be divided into flange type, wafer type, and welded type.
Flange Type Soft Sealing Butterfly Valve
As a component used to cut off the pipeline system and control the flow, fully lugged butterfly valve has been widely used in many fields such as petroleum, chemical industry, metallurgy, hydropower, and so on. In the known butterfly valve technology, the sealing structure is mostly used and its sealing materials are rubber and polytetrafluoroethylene. Due to the limitation of structural characteristics, butterfly valve is not suitable for high temperature, high pressure, corrosion, and other industries. At present, three eccentric metal hard seal butterfly valve is appeared, whose valve body and valve seat are connected components. The sealing surface layer of valve seat shall be made of mild and corrosion resistant alloy. Compared with the traditional hygienic butterfly valve, it has the characteristics of high temperature resistance, light operation, and no friction. Besides, the torque increase of the transmission mechanism can be used to compensate the sealing, which can improve the sealing performance and prolong the service life of the butterfly valve.
Wafer Type Soft Seal Butterfly Valve
Butterfly valve is not only the most ideal opening and closing parts in pipeline, but also the development direction of pipeline opening and closing parts. The valve seat sealing section of single eccentric soft seal Zwick butterfly valve or the bisector of the thickness direction of the butterfly plate is relatively eccentric with the stem rotation center, which makes the butterfly plate sealing surface gradually separate from the valve seat sealing surface during the opening process. When the butterfly plate rotates to 20-25 degrees, the sealing surface of the butterfly plate is completely separated from the sealing surface of the valve seat, which greatly reduces the relative mechanical wear and extrusion between the two sealing surfaces during the opening process. This design mainly relies on the extrusion between the butterfly plate and the valve seat to produce elastic deformation to ensure the sealing of the vacuum butterfly valve.
Welding Type Soft Sealing Butterfly Valve
On the basis of double eccentric butterfly valve, an angular eccentricity is formed between the center line of the valve seat sealing surface and the center line of the high-pressure butterfly valve, which can make the sealing surface of the butterfly plate immediately break away from the valve seat sealing surface at the moment of opening and contact and compress the valve seat sealing surface at the moment of closing. This unique eccentric combination makes full use of the cam effect, so it can completely eliminate the mechanical friction and scratch between the two sealing surfaces of the single flange butterfly valve when the valve is opened and closed, which can also reduce the possibility of wear and leakage. Because the extrusion seal is changed to torque seal, the specific pressure can be adjusted by adjusting the driving torque, which can greatly improve the sealing performance and service life of tri-eccentric lined butterfly valve.