| 摘要 |
1. A method of duct leakage control wherein a sheet-like sealing element is introduced into the duct and is automatically drawn or otherwise guided to the locality of a leak and is caused, by reason of a pressure differential at that locality and attributable to the leak, to be attracted to the leak, thereby to stem or seal the leak. 2. A method according to claim 1, wherein the sealing element is towed towards the known position of a leak and released at the leak. 3. A method according to claim 2, wherein a vehicle towing the sealing element is guided towards the leak from a remote location. 4. A method according to claim 1, wherein said element is conveyed toward said leak by motion of a fluid in said duct and once in the vicinity of said leak is drawn thereinto by differential pressure attributable to the leak. 5. Apparatus for duct leakage control, comprising a sheet-like sealing element disposed in the duct and capable of being automatically drawn or otherwise guided to the locality of a leak and is caused, by reason of a pressure differential at that locality and attributable to the leak, to move into and stem or seal the leak. 6. Apparatus according to claim 5, wherein the sealing element comprises a plurality of individual members, each capable of being carried by a flow of fluid along the duct. 7. Apparatus according to claim 6, wherein different members of said sealing element exhibit differing buoyancies. 8. Apparatus according to claim 6 or claim 7, wherein different members of said sealing element exhibit differing shapes. 9. Apparatus according to claim 5, including sensor means used to locate the leak, and wherein said sensor means is used to transport or guide the sealing member to the leak. 10. Apparatus according to claim 9, wherein the sealing member takes the form of an open-ended frustoconical sheet, somewhat like a wind sock in appearance, towed by the sensor means or otherwise guided by the sensor to the vicinity of the leak, whereupon the sheet is drawn towards the leak by the pressure differential thereacross. 11. Apparatus according to any of claims 5 to 10 inclusive, wherein the sealing member supports, in the form of a coating or otherwise, a medium capable, when forced into contact with the duct, of adhering strongly thereto, thereby anchoring the sealing member firmly in place across the leaking area of the duct wall and sealing the leak. 12. Apparatus according to claim 11, wherein said medium comprises a bonding agent. 13. Apparatus according to claim 12, wherein the bonding agent is contained in microcapsules, which burst in response to the pressure imparted to the sealing element when it is in position to seal the leak. 14. Apparatus according to claim 10, further including pressure sensitive release means, incorporated in the towing link, which enable the towing vehicle to leave the sealing element behind at the site of the leak and proceed alone to a suitable collection point. 15. Apparatus according to any of claims 5 to 14, wherein the sealing element is provided with a location device capable (either by, itself or in co-operation with another element or component) of providing a signal indicative of the location of the sealing means. 16. Apparatus according to claim 15, wherein the location device is passive, and includes a loop of electrically conductive material, the proximity of which can be sensed by a mobile intelligent unit inside the pipe or a suitable external pick-up, or active such as an infra-red, acoustic, radio or optical sender configured to relay signals either directly to the environment outside of the pipe or to a mobile intelligent unit inside the pipe. 17. Apparatus according to any of claims 5 to 16, wherein two or more sealing devices of equal or predetermined relative buoyancy are linked together; the linked devices being encouraged to flow at a selected position within the pipe, depending in part upon the length of the link. 18. Apparatus according to claim 17, wherein the linking connection is constructed to dissolve or change in length during exposure, over a prescribed period of time, to the fluid content of the pipe.
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