Drying oven for indefinite length material

Apparatus for providing an indefinite length of electrical conductor with pulp insulation comprising an adhesive applicator to apply adhesive to the electrical conductor, a drying oven downstream from the applicator, the drying oven comprising a structure defining a drying chamber having an inlet and an outlet for passage therethrough of the conductor, heating means within the chamber to directly dry adhesive on the conductor as it passes through the oven, the chamber surrounded by an annular heat exchanger comprising a plurality of heat exchange members which between them define and separate flow passages extending axially of the chamber and around the chamber, at least a first of the passages being a flow passage for incoming gas, having an inlet for said gas and having an outlet leading into the chamber at a first location, and a second of the passages being a flow passage for outgoing gas from the chamber, having a gas inlet leading from the chamber at a second location spaced from the first location to cause gas flow through said chamber to pass across said heating means, said second passage also having a gas outlet to effect flow of gas heated in the chamber outwardly from said chamber, the heat exchange members provided to cause heat transfer from outgoing gas in said second passage to incoming gas in the first passage.