Heat and sound insulating conduits

摘要

Heat and sound insulating conduits are formed from a metal tube, pref. of Cu, surrounded by a layer of cellular plastic insulation. The plastic layer is surrounded by a helically wound paper strip and finally by a longitudinally split tube, an expansible material being then introduced into the space and the split bonded. According to the improvement a sheet having copolymer at least on the side facing the cellular layer forms the split tube around the helical spacing element and is bonded intimately to the foam.