| 摘要 |
<p>To obviate the need for hydraulic lines from the surface, external water pressure is used to compress a seal member (20) and form a seal with a surrounding pipe (30). Valve (24) is opened at depth to allow water to act on a piston (16), moving it within a chamber (14) so as to compress the seal member (20). A second valve (29) may be opened so that water acts on the opposite end of the piston (16) to release the seal member (20).</p> |
