LIQUID-LEAK DETECTOR CABLE

摘要

1498053 Detecting leaks electrically ASAHI ENG & CONSTRUCTION CO Ltd 21 March 1975 [8 Oct 1974] 11952/75 Headings G1N and G1S To detect liquid leakage from a pipeline 10 an electric cable 11 is laid adjacent the pipeline leakage of liquid between the inner and outer conductors 1, 4 of the cable changing the electrostatic capacity between them. In a preferred embodiment the cable includes an inner conductor 1, polyethylene insulation 2 and a serving 3 for retaining petroleum or other liquid permeating the cable. The serving is covered by a copper braid 4 allowing penetration of the leaking liquid and covered by an anti-corrosive wrap 5 which allows only the leaking liquid to pass through whilst keeping off water. The wrap may be a fibrous tape impregnated with asphalt or petroleum or a copper or iron tape or a porous plastics film of polytetrafluorethylene expanded to an open-cell structure with an average pore size of 0À5-5À0 microns and 85-95% porosity. The leak may be detected by applying an electric pulse to the cable and observing either the reflected pulse on a C.R.O. or the transmitted pulse.