Abstract: A heat recoverable conductive polymeric tubular article shrinks radially when electrical current is passed therethrough. It is powered by elongate electrodes extending along the article along part of the length only of the article, thereby defining an inwardly directed electrode end material of the article preferably has specific electrical properties to compensate for the increased current density that would otherwise exist at the inwardly directed electrode end, and which could lead to burning or hot spot formation.

Abstract: A tubular article comprises an electrically conductive polymeric material. The article increases in wall thickness on recovery. It can be used for example as a duct seal or as an internal coupler or seal for hollow conduits such as pipes. The article may have plain or convoluted walls.

Abstract: A tubular heat recoverable article comprises conductive polymeric material and is heated to effect recovery by the passage of electrical current therethrough. Elongate electrodes are attached on the surface or embedded in longitudinal flanges extending along the article. The flanges also comprise conductive polymeric material but are not heat recoverable, and therefore remain substantially undeformed on recovery other than bending to accommodate transitions. This means that the contact resistance between the electrode and the conductive material of the flange does not increase significantly on recovery.

Abstract: Apparatus and method for heating liquids, e.g. diesel fuel, by means of a conductive polymer heater which does not have an insulating jacket, so that there is direct physical contact between the liquid and electrically conductive parts of the heater. This results in improved heat transfer to the liquid. The unjacketed heater comprises a pair of elongate spaced electrodes embedded in an elongated strip of a conductive polymer, such as cross-linked polyvinylidene fluoride, which exhibits PTC behavior. The heater is positioned in a container through which diesel fuel to be heated flows from an entry port to an exit port. The exterior surface of the polymer strip is exposed and is directly contacted by the flowing diesel fuel.

Abstract: An electrically heat-recoverable assembly comprising a heat-recoverable article and a pair of electrodes. The electrodes supply current to the article without interferring or limiting the way in which the article can be deformed in order to render it heat recoverable. The electrodes are placed and connected to the article in light of the properties of the article, especially its volume resistivity. The assembly significantly reduces the possibilities of arching or sparking while generating sufficient heat that is generated sufficiently uniformly throughout the article.

Abstract: A method for heating diesel prior to filtration by passing the diesel fuel through a heating apparatus including a container having entry and exit ports for the fuel and an elongated electrical heater arranged in spaced apart coils within the container for directing the flow of fuel so that, as the fuel flows from the entry port to the exit port, it flows along an elongate curved path which follows the coils of the heater and which curved path preferably has a length at least eight times the straightline distance between the entry and exit ports. The electric heater is unjacketed and comprises a pair of elongate electrodes embedded in an elongate strip of a conductive polymer composition which exhibits PTC behavior. The exterior surface of the elongate polymer strip is exposed so that it is directly contacted by the diesel fuel flowing through the container.