| 摘要 |
PROBLEM TO BE SOLVED: To enhance energy saving performance by constituting a tubular body of a heat insulating material internally having an air layer and a reinforcing body and covering the surface and rear surface of the tubular body with a sealing material thereby reducing heat loss from a duct. SOLUTION: A heat insulating material 21 is wound spirally in two layers and a reinforcing body 22 is wound spirally in the spiral gap of the heat insulating material 21 in order to ensure the strength of a duct. Inner and outer surfaces of a pipe wall constituted of the heat insulating material 21 and the reinforcing body 22 are covered with a sealing material 23 in order to isolate the inside and outside of the pipe from each other. The heat insulating material 21 is subjected to spot facing on the entire surfaces touching each other and an air layer 24 is formed. Preferably, the material of the heat insulating material 21 has low thermal conductivity and a foamed polyethylene is employed, for example. Preferably, the material of the reinforcing body 22 has such a strength as allowing bending but not allowing flexing and hard polyvinyl chloride is employed, for example. A soft vinyl tape is employed, for example, as the sealing material 23. |
