| 摘要 |
<p>A sealing device is provided for use in a butterfly valve, ball valve or the like wherein a seal ring is provided which forms a seal in co-operation with a rotating valve member, in which the seal is held in position by an annular pressure member which is impelled towards the body of the valve by springs, and whose inner periphery is adapted to form an emergency seal in co-operation with the valve member, should the seal itself be damaged or destroyed by fire.</p> |
