Flexible insulated duct and the method of making the duct

Abstract

An insulated air duct includes a flexible, reinforced, inner tubular core; a layer of partially compressed flexible, resilient fibrous insulation surrounding the core; and a flexible jacket, preferably with a longitudinally extending seam, spaced outwardly from the core and enveloping the layer of partially compressed fibrous insulation. The layer of partially compressed fibrous insulation is formed from a resilient blanket of air laid, randomly oriented, entangled fibers. The resilient blanket may have a low binder content or be binderless with the fibers unbonded and, possibly, lubricated. The lubricant on the fibers facilitates the sliding of the fibers relative to each other, reduces fiber attrition due to abrasion as the fibers move relative to each other; and enhances the resilience of the blanket when subjected to compression whereby the layer of compressed fibrous insulation surrounding the core remains expanded in its partially compressed state, to the extent permitted by a space between the core and the jacket, to provide the duct with good insulating properties and to exert an outward pressure on the jacket to improve the appearance of the jacket. Preferably, the resilient blanket is wrapped about the core while being supported on the jacket so that the blanket will not pull apart during the wrapping process.