GB801711A - Improvements in or relating to electrical heating devices - Google Patents

Abstract

801,711. Electrically heated fabrics. ISOPAD, Ltd., and REIK, H. May 3, 1955 [Feb. 3, 1954], No. 3218/54. Class 39(3) A flat flexible elongated electric heater for wrapping round pipes, containers or other articles, comprises a single length of resistance wire 1 with a coating of glass or asbestos lap or braid doubled back on itself once only to a U shape and woven into or stitched to a strip of glass fabric or asbestos yarn, one or both sides of the strip being folded over to sandwich the wire between layers of the glass or asbestos fabric. The ends of the wire are connected at one end of the heater directly or through conductors to a plug. When the insulated wire is interwoven with a central section of the strip, the two side flaps of the strip are bent over to enclose the wire and the three portions of the strip are stitched together at their edges; or the wire may be interwoven adjacent one edge of the strip, and the remaining two-thirds of the width of the strip may be turned twice over the wire to enclose it. When the wire is stitched along one half of the width of the strip, the other half may be folded over and the edges of the strip stitched together. The element comprises a straight resistance wire or a wire coiled on an insulating core covered by a layer of glass or asbestos braid covered by a waterproof extruded sleeve of silicone rubber, neoprene, or polytetrafluorethylene which may have an extruded cover of nylon or Terylene (Registered Trade Mark). Conductors 5 attached to the ends of the heating wire may be stranded nickel waterproofed by a substance which will mould with the waterproofing material on the heating element. A layer 8 of conducting foil or fine wire mesh may be sewn on the outside of the heater and connected by a conductor 10 to a third prong of the plug to serve as an earth, and this earthing layer may be covered by a further turned-over layer of the glass or asbestos fabric 2. Alternatively earthing wires are woven with an outer portion of the base fabric 2. When an earthed layer is employed, a fuse may be incorporated which on blowing disconnects the heater from the mains. Lapped or braided earthing wires are alternatively wound round the heating element. Several sections of glass or asbestos fabric may be joined end to end with a single heating element. The heater may be wrapped round a pipe or vessel to be heated.