The Triple eccentric butterfly valve seal principle

Posted by bundorvalve on July 24th, 2018

The triple-eccentric butterfly valve employs a sealing system similar to a shut-off valve consisting of a fixed valve seat with the same conical cross-sectional shape and a rotatable sealing surface. However, the three-eccentric butterfly valve adopts a rotary motion (instead of an axial motion), and the shut-off is achieved by the vertebral body tilted with respect to the axis of the pipe at the tip of the cone, which makes the three-eccentric butterfly valve a “stop valve for the angular stroke”.

According to the design of the shut-off valve, a single momentary contact occurs only when the sealing element is in the closed position, which is why the tri-eccentric valve can realize frictionless closing. However, unlike the shut-off valve, the triple-eccentric valve can be fully closed in both directions. Its realization is based on three "eccentricity":

1. The shaft is arranged behind the sealing surface, so that the valve obtains a complete continuous sealing surface.

2. The shaft is set on the side of the pipe/valve centerline and generates a cam effect. During the opening stroke, the seal ring and the valve seat are not in contact, effectively reducing the torque.

3. The centerline of the valve seat and the seal cone is inclined relative to the pipe/valve centerline, completely eliminating the friction between the seal ring and the seat in the 90° travel.

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bundorvalve
Joined: April 20th, 2018
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