| 摘要 |
<p>The spiral of the centrifugal fan is moulded in synthetic cellular material so as to fit accurately inside the box. It has an eccentric recess for the electrical housing and a central recess opening outwards below for connection to a suction conduit. Above it opens into a cavity where the turbine is positioned with its outlet, having a contour corresponding to these. This cavity, together with the cover plate forms the spiral which is usually fitted to the turbine, and the moulding which is of low density polyurethane or polyester foam also acts as the filter element.</p> |
