| 摘要 |
PURPOSE:To lengthen the life of a valve by pouring fresh water just before the third switch valve to fill pipelines in front and in rear of the third switch valve with fresh water, and further opening and closing the above switch valve in the stationary fresh water. CONSTITUTION:The first switch valve group is adapted to feed fresh water to a supply pipe 7, the second group is adapted to feed slurry from the pipe 7 to a transport pipe 9, the third group is adapted to feed flurry to the pipe 7, and the front group is adapted to feed fresh water returned from the pipe 7 to a mixing tank 5. A fresh water pouring pipe 10 with an operation valve 11 is connected just before the third switch valve group, and the operation valve 11 interlocks with the third switch valve in such a manner as to open when the third switch valve is closed. When the third switch valve 3 is closed, the fourth switch valve is closed to repose the flow. The third switch valve is opened when the flow is reposed before opening the fourth switch valve. Thus, the third switch valve is opened and closed in the stationary fresh water, so that the valve plate and valve seat is prevented from being damaged due to collision of slurry during opening and closing of the valve to lengthen the life of the valve. |
