| 摘要 |
<p>An insulating duct for the ventilation systems of tunnels and mines comprises a core material consisting of woven, synthetic fibres coated on one or both faces, a layer of foam on one or both sides of this core, and a covering foil having a vapour-deposited metal foil on its outer face. The foam is pref. of PVC, and the metal foil is pref. aluminium. This material provides a high level of thermal insulation, thus preventing the incoming air from becoming heated, and also adequate strength accompanied by flexibility.</p> |
