| 摘要 |
<p>FIRE-SAFE BALL VALVE ( ) An improved, soft-seated fire-safe ball valve is disclosed. The ball valve includes a body having a central passageway, a ball member positioned in the passageway, and a pair of radially inwardly extending shoulders in the passageway disposed circumferentially thereof on opposite sides of the ball member. The ball member includes a fluid flow opening therethrough and is mounted for selective rotation between valve open and closed positions to control fluid flow through the valve. An improved seat assembly is provided comprising a rigid reinforcing ring, an elastic seat ring supported by the reinforcing ring and configured for fluid sealing engagement to the ball member, and a deformable, heat resistant secondary seat ring interposed between the elastic seat ring and an associated one of the pair of shoulders. Also, a weir ring may be advantageously received in the seat ring. Upon fire damage to the elastic seat ring, the secondary seat ring engages the ball member to seal the valve. The weir ring inhibits extrusion of a substantial portion of the seat ring such that the seat assembly operates to maintain a fluid-tight seal upon partial destruction of the elastic seat ring.</p> |
