| 摘要 |
The present invention relates to an ventilation duct construction and a method which increases the fire-retardant capability of a ventilation duct. According to the invention, an improved fire-retardant capability of a ventilation duct or sound absorber is obtained by providing the ventilation duct with a shielding sheet at a distance from the same so that an air gap is formed therebetween. The time during which the outside temperature of the construction can be kept down is prolonged, while the construction remains compact.
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