Double eccentric butterfly valve is further improved on the basis of single eccentric butterfly valve. Its structural feature is that the axis of the valve stem deviates from both the center of the disc and the center of the body. The effect of double eccentricity enables the butterfly plate to quickly disengage from the valve seat after the valve is opened, which greatly eliminates unnecessary excessive squeezing and scraping of the butterfly plate and the valve seat, reduces the opening resistance, reduces wear and improves Increased valve seat life. The greatly reduced scraping also makes the double eccentric butterfly valve also adopt metal seat, which improves the application of butterfly valve in high temperature field.
Pneumatic centerline butterfly valve refers to the center of rotation of the butterfly valve disc (that is, the center of the valve shaft) and the center of the valve body. It is connected to the pneumatic actuator by a direct connection method. It can be divided into pneumatic wafer centerline butterfly valves according to different connection methods And pneumatic flange centerline butterfly valve, butterfly valve has automatic centering function (up, down, left and right), and its seals are generally made of seal structure, common seal materials are rubber, polytetrafluoroethylene and so on. The disadvantage is that because the opening and closing of the butterfly plate and the valve seat are always in a squeezed state, it is easy to scratch and cause fast wear.