Patent ID: 7032882

Claim:
A valve assembly comprising: a housing having a flow channel and an annular surface surrounding the flow channel so as to define an axis of the flow channel; a slide plate located in the housing and movable (a) transversely to the axis of the flow channel between an open position, wherein the slide plate allows flow through the flow channel and does not block the cross section of the flow channel along the axis of the flow channel, and a soft closed position, wherein the slide plate is located within the cross section of the flow channel, and (b) axially along the axis of the flow channel from the soft closed position to a hard closed position, wherein the flow through the flow channel is blocked; and a seal ring positioned between the annular surface of the housing and the slide plate, wherein the seal ring includes a first side extending generally parallel with the axis of the flow path, a second side spaced radially outwardly from the first side and extending generally parallel with the axis of the flow path, a first surface extending between the first and the second sides and facing towards the annular surface of the housing, and a second surface axially spaced from the first surface and extending between the first and the second sides and facing towards the slide plate, wherein the second surface includes a continuous annular sealing portion for contacting the slide plate when the seal ring is positioned against the slide plate when the slide plate is located in the hard closed position, so that a fluid-tight seal can be formed between the continuous annular sealing portion and the slide plate when the slide plate is in the hard closed position, and at least one unobstructed passageway is positioned between the annular sealing portion and the second side of the seal ring for increasing fluid flow through the flow channel between the seal ring and the slide plate as the slide plate moves between the soft closed position and the hard closed position.