Abstract: Detection of liquid leaks and other changes in variables is disclosed. The event causes two elongate conductors to become electrically connected at a location which is determined by the event, thus creating a system in which the connection point can be located by measuring the potential drop from one end of one of the conductors (called the locating member) to the connection point. The system comprises a balancing component so that its sensitivity is not dependent on the location of the event along an elongate path. A fixed current flows through the connection, so that the result is independent of the resistance of the connection. The locating member can be a continuous resistive wire, coated with a conductive polymer; such a locating member can form part of a sensor cable in which the elongate components of the circuit are in a wrapped configuration. Alternatively the locating member comprises a plurality of discrete resistors.

Abstract: An elongate sensor for detecting and locating presence of a liquid, e.g. water or a hydrocarbon. The sensor includes first and second elongate members which are spaced apart from each other and each of which is a metal conductor covered by a conductive polymer; a third, insulated elongate conductor; and an elongate insulating core. At least one of the elongate members is helically wrapped around the core. Presence of the liquid at any point along the length of the sensor causes the first and second members to be electrically connected at that point, creating a system in which the potential drop down one of the members can be measured and the location of the connection determined.

Abstract: A sensor cable for detecting the presence of electrically conductive liquids, e.g. water. The cable has decreased sensitivity to contamination and condensation than conventional cables which are covered by braids. First and second elongate conductors are positioned in first and second channels which partially surround the conductor and are part of first and second insulating support members; each channel has at least one shoulder which extends outwardly from the channel beyond the conductor. The channels are positioned so that when the cable is placed on a flat substrate in any position, neither the first nor the second conductor contacts the flat surface and at least one first shoulder and at least one second shoulder make intermittent contact with the flat surface. In a preferred embodiment, the first and second conductors follow a generally spiral path down the length of the cable.

Abstract: Detection of events, e.g. liquid leaks and other changes in varibles. The event causes two conductors to become electrically connected, and thus creating a system in which the connection point can be located by measuring the potential drop from one end of one of the conductors (called the locating member) to the connection point. Preferably a fixed current flows through the connection, so that the result is independent of the resistance of the connection. The locating member can be a continuous resistive wire, preferably coated with a conductive polymer; such a locating member can form part of a sensor cable in which the elongate components of the circuit are in a wrapped configuration, or part of a cable in which the conductors are separated by a member shaped to prevent capillary action of a liquid from connecting the conductors. Alternatively the locating member comprises a plurality of discrete resistors.

Abstract: Methods of preventing corrosion in which current flows between the to-be-protected substrate and a distributed electrode whose electrochemically active surface is provided by an element which is composed of a conductive polymer and which is at least 500 microns thick. In one embodiment, the electrode is a flexible strip comprising a highly conductive core. e.g. of copper, and a conductive polymer element surrounding the core. In another embodiment, the electrode is a conductive polymer layer which conforms to the surface of the substrate but is separated from it by a layer of insulation.

Abstract: Corrosion protection systems which make use of a barrier which is placed between a corrodible substrate and a counter-electrode. The barrier can provide more uniform current distribution on the substrate, and/or enable the counter-electrode to be more easily maintained or replaced, and/or reduce the rate at which the current density on an elongate electrode changes with distance from the power source, and/or provide a controlled environment around the electrode to improve its efficiency.

Abstract: Methods of preventing corrosion in which current flows between the to-be-protected substrate and a distributed electrode whose electrochemically active surface is provided by an element which is composed of a conductive polymer and which is at least 500 microns thick. In one embodiment, the electrode is a flexible strip comprising a highly conductive core, e.g. of copper, and a conductive polymer element surrounding the core. In another embodiment, the electrode is a conductive polymer layer which conforms to the surface of the substrate but is separated from it by a layer of insulation.