An eccentric butterfly valve functions in a similar way to a standard butterfly valve, but with one key difference: the disc (butterfly) is offset from the center of the valve body.

A standard butterfly valve has a disc that rotates about an axis in the center of the valve body. This opens and closes the valve in a symmetrical manner.

In an eccentric butterfly valve, the disc rotates about an axis that is offset from the center of the valve body. This makes the opening and closing motion asymmetrical.

The eccentric butterfly valve manufacturer primary purpose of this eccentric design is to achieve full closure of viscous or sticky fluids that tend to hang up in the valve seat area. Since the disc does not center perfectly over the seat when fully closed, it helps squeeze out any trapped material.