| 摘要 |
<p>The duct is made of one or more layers of cardboard or cardboard-like flat material. One or more sides has grooves to lend flexibility and to allow the duct to be fitted to the geometry of its environment. The grooves form folds in the sides of the duct making it concertina-like. The folds comprise noncombustible flexible fibres, threads, tapes or thin wires lying across the fold and fixed to the flat material and crosslinked with one another.. The duct is for the cables of heating and air conditioning installations and can also be used for the air ducts themselves. Simple assembly of duct sections at place of installation. Occupies relatively little space during transportation.</p> |
