Single Eccentric :

Design : The center of Stem rotation (Os) is moved from the centerline of Disc (Od). The face of Seat and Seal are conical.

Feature : There are interference between Seal and Seat, So this is only applicable to soft Seated Valve.

Double Eccentric :

Design : The centerline of Stem rotation (Os) is moved from the centerline of Disc (Od). And the center of Stem rotation (Os) is moved from the Centerline of Pipe (Lp).

Feature : The Friction between seal and seat is reduced. The materials of Seat must be relatively soft or highly elastic.

Triple Eccentric Design :

The centerline of Stem rotation (Os) is moved from the centerline of Disc (Od). The center of Stem rotation (Os) is moved from the Centerline of Pipe (Lp). And the centerline of the cone of the seal face (Lc) is rotated from the centerline of the Pipe (Lp).

Feature : The interference between the Seal and Seat is eliminated to ensure a long cycle life with this geometry. This design can suit to metal Seat and used in high temperature and high pressure.