Flexible ducting for air conditioning system - comprises foil strips joined at narrow edges and wound spirally over mandrel

摘要

Thin strips of metallic foil are placed over each other and joined along their narrow edges. The lengths thus formed are flexible but have enough thickness to form the sides of a duct. They are wound spirally over a mandrel to form a circular tube. The long edge of one turn overlaps the long edge of the preceding turn and is sealed to it to form an air tight joint. A spiral wire can be put on the mandrel and fixed to the inside of the flexible strip as the latter is wound over it to give added stiffness.