| 摘要 |
The invention concerns a bore sealing valve which is operated by liquid pressure, typically water. The valve has a first member defining an internal bore of round cross-section and a second member which can move in opposite directions in the bore. One of the members has a shoulder and the other a recess accommodating a flexible seal. The seal flexes radially relative to the recess, under the effects of differential pressure in respective high and low pressure regions of the byre, when the second member moves in one direction in the bore. This makes sealing engagement with the shoulder to close the valve and isolate the high and low pressure regions of the bore from one another. The seal disengages from the shoulder when the second member moves in the opposite direction in the bore to open the valve and place the regions of the bore in fluid communication. That end of the seal which engages first with the shoulder on closure of the valve and which disengages last from the shoulder on opening of the valve is closer to the low pressure region of the bore than the opposite end of the seal. With thes e features, the bore sealing valve is suitable for use in a water environment.
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