| 摘要 |
A thermally insulating sleeve 10 for pipe(s) or cable(s) 22 comprises a generally tubular wall portion 12 formed from heat resistant material, and a heat-activatable layer 16 on the interior surface 18 of the wall portion 12. When the heat-activatable layer 16 is subjected to heat, it increases in thickness to improve the thermal insulation of the sleeve 10. Only that part of the heat-activatable layer 16 that is nearest to the heat source increases in thickness, which serves to move the pipe(s) or cable(s) 22 away from the heat source, and closer to the surface located furthest from the heat source for dissipation of the heat through the sleeve at this surface location. The heat-activatable layer 16 may comprise a material that expands on exposure to heat (as shown), the layer 16 preferably also contracting again on cooling. Alternatively, the heat-activatable layer 16 may comprise a compressed thermally insulating material with means to retain this material in its compressed state, the retaining means acting to release the thermally insulating material on being subjected to heat. In this case (shown in figures 3 and 4), the heat-activatable layer 36 most preferably comprises a plurality of plastic monofilaments 37 retained in a compressed state by a wax 40 that melts on exposure to heat and releases the monofilaments 37 to extend normal to the interior surface 38 of the wall portion 32. |
