The Differences and Functions of Single Eccentric, Double Eccentric and Triple Eccentric Butterfly Valves.
Simple eccentric butterfly valve
In order to solve the extrusion problem between the disc and the valve seat of the concentric butterfly valve, the single eccentric butterfly valve is manufactured. Distribute and reduce excess extrusion of the top and bottom of the flapper plate and valve seat. However, due to the single eccentric structure, the scraping phenomenon between the disk and the valve seat does not disappear during the entire valve opening and closing process, and the scope of application is similar to that of the concentric butterfly valve, so it is not widely used.
Double eccentric butterfly valve
On the basis of the single eccentric butterfly valve, it is the double eccentric butterfly valve this is very common these days. Its structural feature is that the shaft center of the valve stem is deviated from the center of the disc and the center of the body. The effect of double eccentricity allows the disc to separate from the valve seat immediately after the valve opens, largely avoiding unnecessary excessive extrusion and scratches between the disc and the valve seat, reducing opening resistance, reducing wear and tear, and improving seat life . Scratching is greatly reduced and at the same time the double eccentric butterfly valve a metal valve seat can also be used, which improves the application of the butterfly valve in the high temperature area. However, since its sealing principle is a position sealing structure, that is, the sealing surface of the disc and the valve seat are in line contact, and the elastic deformation caused by the disc extrusion of the valve seat produces a sealing effect, so it has high requirements for the closed position (especially metal valve seat ), low pressure rating, which is why it is traditionally believed that butterfly valves cannot withstand high pressure and…