| 摘要 |
<p>A butterfly valve is described which comprises a valve disc (16) located within a flow passage (14) provided in a housing (12) and engageable with a seat (22) provided within the housing, the valve disc and the housing cooperating with one another, when the valve disc occupies a closed position, to define an annular void (28) extending around the periphery of the valve disc at a position spaced from and independent of the main valve seat, an inlet port (30) and an outlet port (32) communicating with the void to allow the supply of sealant to the void to form a seal between the valve disc and the housing.</p> |
