| 摘要 |
<p>The ventilator roof cover is made of concrete or a ceramic with an opening which may be coupled with a louvred air inlet or flexible pipe (6). Around the outer periphery of the ventilator housing is a fringe which contacts the roof at an acute angle and is of non-rigid construction (3). To protect the ventilator from entry of foreign bodies, a flexible outer member (7,8) is provided in the form of a castellated cylinder with a central opening including circular arcs. A straight bar may be fitted underneath the internal flanges of the flexible cover to allow it to be removed. The design enables the ventilator to be fitted to a sloping roof if required.</p> |
