| 摘要 |
<p>A valve body having a circular throat and three vanes mounted for rotation within the circular throat of the valve body. The three vanes comprise two outlying vanes, each having two opposed circular peripheral edges configured so that one of the two opposed circular peripheral edges fits against a circular throat when the vanes are in the closed position. A central vane, preferably of hour glass configuration, is located between the two outlying vanes so that all three vanes nest within the circular throat and against one another when the valve is a closed position. Each of the vanes has a symmetrical axis of rotation and is mounted within the circular throat of the valve body so as to rotate about the symmetrical axis. <IMAGE></p> |
