Centerline Butterfly Valves and Eccentric Butterfly Valves

For centerline butterfly valves and eccentric butterfly valves, the sealing and opening states can be changed by setting the position of the shaft of the valve plate.

In the same situation, when the valve is opened, the rotation angle required for the valve plate to separate from the seal is smaller than the other, and the torsion force received by the valve is larger than the other at each opening degree.

Eccentric butterfly valves can be subdivided into single eccentric butterfly valves, double eccentric butterfly valves and triple eccentric butterfly valves according to different structural forms.

Triple eccentric butterfly valve

For high temperature resistance, hard seal must be used, but the leakage is large; for zero leakage, soft seal must be used but not resistant to high temperature.

In order to overcome the contradiction of the double eccentric butterfly valve, the butterfly valve was eccentric for the third time. The so-called third heart is that the shape of the sealing pair is not a positive cone, but an oblique cone. The unique feature of the triple eccentric butterfly valve is that the valve on which the butterfly plate is installed is a three-section shaft structure. The plate is installed on the intermediate shaft section. Such an eccentric structure makes the butterfly plate a double-eccentric shape when it is fully open, and a single-eccentric shape when the butterfly plate turns to the closed position. Due to the effect of the eccentric shaft, when it is close to closing, it moves a distance into the sealing cone surface of the valve seat, and the butterfly plate coincides with the sealing surface of the valve seat to achieve a reliable seal.

Double eccentric butterfly valve

The most widely used double-bias valve is currently the most widely used double-bias valve, which is further improved on the basis of single eccentric butterfly valve. Its structural feature is that the shaft center of the valve stem deviates from the center of the butterfly plate and the center of the valve body. The effect of double eccentricity makes the butterfly plate break away from the valve seat immediately after the valve is opened, greatly eliminating unnecessary excessive extrusion of the butterfly plate and the valve seat, lightening the scratching phenomenon, reducing the opening resistance distance, reducing wear, and improving valve performance. seat life.

Single eccentric butterfly valve

In order to solve the extrusion problem between the butterfly plate and the valve seat of the concentric butterfly valve, a single eccentric butterfly valve was produced. , Reduce the excessive extrusion of the upper and lower ends of the plate and the valve seat.

Centerline butterfly valve

The structural feature of the centerline butterfly valve is that the shaft center of the valve stem, the center of the butterfly plate and the center of the valve body are at the same position. Because the butterfly plate and the valve seat are always in the state of extrusion and scraping, the resistance distance is large and the wear is fast. The structure is simple and convenient. In order to overcome extrusion and scratching and ensure sealing performance, the valve seat is basically made of elastic materials such as rubber or polytetrafluoroethylene.