Patent ID: 7758017

Claim:
A butterfly type valve comprising: a valve body defining a flow passage therein; a closure disc disposed in the flow passage, the closure disc having an axis of rotation about which the closure disc rotates between open and closed positions with respect to the flow passage; a resilient cylindrical body liner disposed within the valve body, the resilient cylindrical body liner having a circumferential sealing surface that is engaged by the periphery of the closure disc to establish a seal when the closure disc is rotated to a closed position; a resilient support being at least partially interposed between the valve body and the resilient cylindrical body liner, the resilient support having a thickness that gradually tapers from a portion of the resilient support that is adjacent the rotational axis of the closure disc to a portion of the resilient support that is transversely distant from the rotational axis of the closure disk, wherein the resilient support tapers to a reduction in thickness of at least 0.050 inches at the portion of the resilient support that is transversely distant from the rotational axis.