Patent ID: 7032880

Claim:
A valve, comprising: a valve body having a valve chamber and an inlet passage and an outlet passage in communication with the valve chamber; a valve member positioned in the valve chamber and movable between an open position and a closed position, the valve member having a flow passage formed therethrough for providing fluid communication between the inlet passage and the outlet passage of the valve body when the valve member is in the open position; and a seat assembly extending about the inlet passage and engaging the valve member, the seat assembly comprising: an annular seat carrier having an annular groove formed therein; and a seat positioned in and extending from the annular groove of the seat carrier, the seat having an inner side, an outer side, and a plurality of spaced apart, concentric seal rings extending from the inner side of the seat to the outer side thereof, the seal ring nearest the inner side of the seat being engageable with the valve member to provide an innermost seal when the seat assembly is acted upon by a pressure within a pressure range and the seal ring nearest the inner side of the seat being deflectable in a radially outward direction and out of sealing engagement with the valve member when the pressure exceeds the pressure range to cause the adjacent seal ring to provide the innermost seal.