| 摘要 |
<p>The roof unit comprises a short duct providing a ventilation opening. This is closed by a panel (16) fitting over it hinged (20) at one end. For normal ventilation, this panel is opened to permit air to pass out at the sides. If additional ventilation is required, such s for clearing smoke, the pivoting panel can slide along tracks (18) in a subframe forming part of the main ventilation panel frame. This panel can also be glazed for additional lighting and the unit is operated, manually or automatically, by cables (22, 26).</p> |
