| 摘要 |
PURPOSE:To hold a seal function even when a fire is caused, by both mounting a noninflammable seal ring on the slide contact peripheral surface of an outer ring with a housing internal wall and forming a valve chamber, equipped with a passage communicating a back face side and a cavity side of the outer ring, in the outer ring. CONSTITUTION:A noninflammable seal ring 9 is provided in an outer ring 3b. A passage 10 and a passage closing vlave 11 are provided in the outer ring 3b. If inflammable seal rings 4, 6, 14 are completely lost, the closing valve 11, being pressed by a spring 15 set to its back face, closes the passage 10, causing the communicated condition between a cavity 7 and an enclosed chamber 8 to disappear. Further the noninflammable seal ring 9, being mounted to the outer ring 3b, causes fluid to never even to leak at all into a side of the cavity 7. Accordingly, the pressure P1 in a fluid flow hole 2 is transmitted between an inner ring 3a and a housing internal wall surface 1a to reach the enclosed chamber 8, pressing the whole unit of a seat retainer 3 to a valve body 5. In this way, a seal point S' of metal touch is generated. |
