| 摘要 |
<p>A fire-safe valve structure (10) has a metal seat (52 and 54) with an annular groove (56) therein in which a sealing ring (50) is positioned in face-to-face contact with a valve member (28) movable between open and closed positions. The annular groove (56) has an annular space (66) behind the resilient sealing ring (50) to permit displacement of the sealing ring (50). A shim of fusible material (68), which sublimates at a predetermined temperature, is associated with the annular space (66) and holds the sealing ring (50) in contact with the valve member (28). Upon sublimation of the sublimable material and subsequent passage of the gaseous sublimable material from the annular space (66), the sealing ring (50) is displaced within the annular space (66) and the valve member (28) moves into a tight metal-to-metal contact with the metal seat (52 and 54). </p> |
