Patent attributes
Various exemplary embodiments of a butterfly-type valve that provide a reduction in the unseating torque are disclosed that include a valve body defining a flow passage therein, and a closure disc disposed in the flow passage that has an axis of rotation about which the closure disc rotates between open and closed positions. The valve includes a cylindrical body liner disposed within the valve, which includes a circumferential sealing surface that is engaged by the closure disc to establish a seal when the closure disc is rotated to a closed position. At least one resilient band is at least partially interposed between the valve body and the cylindrical body liner, and at least a portion of the resilient band is tapered to a reduced thickness. The taper reduces the forces associated with the engagement by the closure disc, to thereby reduce the unseating torque required to open the closure disc.
