| 摘要 |
PCT No. PCT/GB87/00796 Sec. 371 Date Jul. 11, 1990 Sec. 102(e) Date Jul. 11, 1990 PCT Filed Nov. 9, 1987 PCT Pub. No. WO88/03597 PCT Pub. Date May 19, 1988.The packing-seal is shown in use in a borehole as a level-isolating seal for a groundwater sampler. The packing-seal shown includes an expandable annulus of Dowell (TM) water-expandable material. Surrounding that is a pressure-sleeve of rubber. A sheet of woven Kevlar (TM) is wrapped circumferentially around the sleeve and the Dowell annulus, such that the ends of the Kevlar sheet overlap. Outside the Kevlar is an outer rubber sleeve. Upon expansion of the packing seal to fill the borehole, the Kevlar sheet unwraps to allow the Dowell to expand without restraint. Once the packing seal has filled the borehole, the Kevlar sheet is prevented from unwrapping further. If the borehole contains a fissure the Kevlar provides a rigid bridge over the fissure, and prevents the packing-seal from ballooning out into the fissure.
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