| 摘要 |
<p>The static-dynamic suction device for gaseous media also includes acoustic inoculation. Typically, this can comprise a mass of sound-insulation material (31) such as rock wool or glass fibre, accommodated in the top or bottom sections (2, 3). If it is contained in the top one, the bottom one can be of perforated sheet metal. The top one can be of larger diameter than the bottom one, and where the device is used as a roof ventilator for a factory etc. it can be of oblong shape.</p> |
