Abstract: A valve seal for a butterfly valve comprises a U-shaped annular seating member disposed in an annular slot in the valve body and a retaining ring for holding the seating member in place. The seating member cross-section comprises two legs and a bight portion connecting them. A first one of the legs is captured between the retaining ring and valve body to hold the seating member in the slot and enable limited rotational movement of the seating member. A radially inwardly projecting extension on the bight terminates in an annular sealing surface that cooperates with the valve disc. The seating member divides the slot into first and second axial sides in fluid pressure communication with the valve chamber. The seal also comprises an annular open-helical back-up member disposed in an annular cavity formed in the slot by the legs and bight portion of the seating member. The annular cavity is in fluid pressure communication with the second axial side of the slot.

Abstract: A power-driven quarter-turn valve actuator includes a reciprocating drive member in the form of a rod mounted perpendicularly to and spaced a preselected distance from a valve stem. A crank arm is coupled to the valve stem so that the axis of the crank arm makes an angle of between approximately 60.degree. and 100.degree. with a line intersecting the stem axis and perpendicular to the rod axis when the valve is shut and makes an angle of between minus 30.degree. and plus 10.degree. with said line when the valve is fully open. A link member connects the outer end of the crank arm to a point on the reciprocating rod. The preselected distance between actuator rod and valve stem, and the lengths of the crank arm and link, are chosen to produce a variable actuator torque output curve that closely matches the operating torque requirements of the valve.

Abstract: A valve seal mechanism for use in pressurized fluid systems subject to fire risk, the seal having a soft seat to provide essentially zero leakage at normal operating temperatures and a backup hard metal seating surface capable of holding leakage to extremely low rates in the event of temperatures high enough to destroy the soft seat material. The seal mechanism is in the form of a hard metal seal ring adapted to fit within an undercut circumferential groove in a valve seat. The metal seal ring has a central inner circumferential rib adapted to extend through the groove opening for mating engagement with a sealing surface on the circumference of a valve disc. The rib of the metal seal ring itself has a circumferential undercut groove into which is tightly fitted a seal ring of material softer than the metal of the seal ring, the soft seal ring protruding beyond the adjacent inner surface of the rib to provide a primary valve seat surface.

Abstract: A positive shut-off seal mechanism for use in pressurized fluid systems subject to high temperatures or fire risk. The seal mechanism includes a metallic valve seat in the form of an annular thin-walled skirt-like lip, preferably formed in a valve seat insert ring or retaining ring, the lip extending generally upstream toward the high pressure side of the valve. The edge of the lip engages a mating circumferential sealing surface of a valve disc, preferably at a location downstream from the plane of maximum disc diameter, with an interference fit to provide a preloaded radial sealing force between the edge of the lip and the sealing surface of the disc. The annular lip preferably forms the downstream side of an undercut groove for a resilient seal ring that provides a primary seal, the engagement of the lip edge with the sealing surface of the valve member providing a metal-to-metal backup seal in the event of damage to or destruction of the resilient seal ring.