Patent ID: 7409964

Claim:
In a valve, the combination comprising a) a valve chamber, having a flow inlet and a flow outlet, b) a valve operator outside the chamber, c) a stopper in the chamber and operatively connected with the operator for movement toward and away from seat structure in the chamber, to move toward and control flow from the valve via said outlet, d) and said seat structure including first and second seats, said stopper located to seat on the first seat, e) there being a flexible sealing lip carried by the stopper and flexing in engagement with the second seat when the stopper seats on the first seat, f) the lip being annular and extending about a stopper annular surface that engages the first seat, the lip radially spaced outwardly and away from the first seat in lip flexed condition when the stopper seats on the first seat, the second seat being a flat planar surface facing in the same direction as the first seat projects, the lip projecting convergently toward the flat surface, the stopper and lip forming an annular recess to receive the first seat and a projection carrying the first seat spaced radially inwardly of the lip, there being a first gap between the lip and one side of the projection, and a second gap between the opposite side of the projection and structure associated with the stopper; g) the first seat extending annularly about a flow port directly between two chamber portions respectively extending to opposite sides of said flow port and respectively associated with said inlet and outlet, when the valve is open, said chamber portions and said port defining a flow path that extends substantially linearly and adjacent the stopper at a substantial angle or angles relative to an axial direction of stopper movement toward and away from said seat structure, h) and including telescopically interfitting parts, which are relatively movable, one part connected to the handle, and the other part carrying the stopper, said one part having threaded connection to the chamber, for advancing said one part toward the seat, in response to handle rotation, and wherein said one part defines a drain port to drain fluid from the interior of said one part wherein said other part projects, and said parts have a sealing position or position in which communication from the chamber interior to aid drain port is blocked, and said parts said part define interconnecting passages to supply exterior air to flow past the stopper via said lip, in closed position of the stopper, to break liquid back siphonage.