Flange ball valve closing process:
法兰球阀的关闭过程：
1, close, turn the hand wheel clockwise, the stem begins to drop and make the ball leave the seat and start to rotate.
1、关闭时，顺时针旋转手轮，阀杆开始下降并使球体离开阀座开始旋转。
2. Continue to rotate the handwheel, and the valve stem is acted by the guide pin embedded in its upper spiral groove, so that the valve stem and the ball rotate 90° at the same time.
2、继续旋转手轮，阀杆受到嵌于其上螺旋槽内的导销的作用，使阀杆和球体同时旋转90°。
3. In the last few turns of the hand wheel rotation, the angular plane at the bottom of the valve stem is mechanically wedged to compress the ball, so that it is tightly pressed on the seat to achieve seal.
3、手轮转动的后几圈，阀杆底部的角形平面机械地楔向压迫球体，使其紧密地压在阀座上，达到密封。
4, about to close, the ball has been rotated 90° without contact with the seat.
4、快要关闭时，球体已在与阀座无接触的情况下旋转了90°。
