| 摘要 |
<p>An air-ventilating valve is adapted to allow the ambient atmosphere to enter a conduit when the ambient pressure exceeds the pressure of gas in the conduit by a essentially predetermined amount, and which also blocks the release of gas from the conduit to the ambient atmosphere. The valve includes two generally coaxial upstanding valve seat projections (6, 7) which lie essentially in a mutually common plane, and a vertically movable valve body (20) which includes a ring-shaped sealing element (4) which bridges an annular gap (5) between the upstanding projections (6, 7) when the valve is closed and sealingly abuts respective sealing projections (6; 7). The valve body (20) is adapted to move to a valve closed position under the influence of gravity. At least one upstanding projection (6, 7) is formed by two radially separated ridges (31, 32) which define an annular trough (33) therebetween. The ridges (31, 32) are both intended to lie essentially tangential to the sealing element (4) when the valve is closed. <IMAGE></p> |
