| 摘要 |
<p>PCT No. PCT/EP90/00067 Sec. 371 Date Jul. 22, 1991 Sec. 102(e) Date Jul. 22, 1991 PCT Filed Jan. 12, 1990 PCT Pub. No. WO90/08276 PCT Pub. Date Jul. 26, 1990.A gate valve has a one-piece casing which contains a valve chamber. The casing is provided with a tubular stub on either side of the chamber, and the stubs serve to connect the valve to a pair of pipes. The chamber has a non-circular sealing surface which is inclined to the direction of flow. A valving element having a non-circular sealing surface complementary to the sealing surface of the chamber is insertable in the latter via a selected one of the stubs. Following insertion, the valving element is connected to a spindle. Both the valving element and the spindle are held against rotation, and movement of the valving element towards and away from the sealing surface of the chamber is achieved by a rotary nut which is threaded onto the spindle. The sealing surface of the valving element delimits a region having a maximum dimension greater than the maximum dimension of the selected stub as considered in planes normal to the flow direction.</p> |
