Fire-resistant ventilation or smoke evacuation duct for building has rectangular section with wall panels of plaster/vermiculite mixture and metal frame

摘要

The duct, running the whole height of a multi-storey building, consists of a vertical tube (1) of rectangular cross-section, having at least two walls made from assembled rectangular plates (2) made from a mixture of plaster and vermiculite with adjoining edges (3, 6). The panels are reinforced by a metal frame (5) and coated on the outside by a sprayedon layer (9) of plaster and vermiculite mixture. Each of the panels (2) has a smooth inner surface, and an outer surface with a series of equallyspaced parallel semi-circular section grooves (4) to receive reinforcing tubes of the metal frame.