| 摘要 |
<p>A ball valve of the trunnion type comprises a valve housing (I) having, preferably, concentric oppositely directed inlet and outlet openings (4, 5), each provided with an internal seat (12, 12'), and a reversible ball-shaped valve body, the valve ball (2), which is formed with a passage in the form of a centrally through-going bore (3), adapted to be brought sustantially into alignment with said inlet and outlet (4, 5) in the open position of the valve, and wherein the valve ball (2) is adapted to close the passage through the valve housing in the closed position of the valve, while maintaining a sealed condition at the seats (12, 12') of the valve housing. In order to provide a ball valve of this kind wherein the ball mechanically, without spring force and/or differential pressure, can be rotated into closed position, maintaining optimum sealing at both seats (12, 12') of the valve housing, the valve ball (2) is provided with two diametrally opposite seals (15, 15') which, in the closed position of the valve, simultaneously, are adapted to cooperate sealingly with one of the seats (12, 12') of the valve housing (1) each; the sealing surfaces (17, 17', 16, 16') of the housing seats and the ball seals extending eccentrically with respect to the ball's rota tion point constituted by the geometric centre thereof. Because of the eccentric design of the sealing surfaces of the seats/seals, the sealing action is optimalized with increasing mechanical tightening force and, in the open position of the valve, at each of the seats (1 2, 12') of the valve housing, there being formed a slot having a rather large flow area into the interior of the valve hou sing, allowing efficient flushing of the internal components of the valve by means of a small partial flow of the fluid flowing th rough.</p> |
