| 摘要 |
<p>A fume cupboard (1) the exhaust system of which includes a two-stage vortex amplifier (5, 6) the control ports (9) of which are closed successively as the fume cupboard door (2) is raised thereby to alter the flow characteristics of the exhaust system in such a manner as to make the velocity of air entering the fume cupboard (1) substantially independent of the position of the door (2) of the fume cupboard (1).</p> |
