| 摘要 |
<p>A valve of the membrane valve type comprises a valve body with two fluid flow channels (5, 5') separated by a land portion which forms a valve seat (6) having a sealing surface for co-operation with a flexible membrane (7) mounted over a duct (8) which opens in front of the valve seat and is arranged for fluid pressure actuation of the membrane between a closing position, where the membrane (7) sealingly contacts the valve seat (6), and an opening position where there is a flow channel communicating space (11) between the valve seat (6) and the membrane (7). The valve is characterized in that the sealing surface of the valve seat (6) comprises (i) a primary sealing surface (10) located nearest and facing the membrane, and (ii) a secondary sealing surface (12, 12') provided on each fluid channel side of the valve seat, so that when the valve is closing, the membrane (7) successively seals against the primary sealing surface (10) and the secondary sealing surfaces (12, 12'), and, inversely, when the valve is opening, the membrane (7) is successively separated from the secondary sealing surfaces (12, 12') and the primary sealing surface (10).</p> |
