| 摘要 |
<p>PURPOSE: An insulating duct is provided to constantly maintain the insulation properties of a pipe by retarding the diffusion of a propellant gas and to make duct installation easy by making a duct flexible and bendable. CONSTITUTION: An insulating duct comprises at least one inner pipes, an insulation layer made from foamed polyurethane or polyisocyanurate, a thermoplastic outer cover, and a plastic foil(3) prepared between the insulation layer and the outer cover. The plastic foil consists of many layers(3.1,3.2,3.3). One of the layers is non-transmissive against the propellant gas in the cell of the foamed polyurethane or polyisocyanurate. The layer facing the outer cover and the layer facing the insulation layer are adhered to the non-transmissive layer.</p> |
