| 摘要 |
A flow control apparatus for controlling the flow of a low pressure air stream in an air duct of an air ventilation system includes a conduit section (1) having spaced upstream and downstream ports (8, 9) in upstream and downstream portions thereof, a redirecting member (7) in the conduit section (1) for redirecting air in the upstream portion thereof so that it passes outwardly through the upstream port (8), and a loose flexible membrane (3) operable for redirecting air passing outwardly through the upstream port (8) so that it passes back inwardly through the downstream port (9). The apparatus further includes an outer housing (2) defining an enclosed chamber around the outer side of the membrane (3) and a controller (23) for controlling the air pressure in the membrane (3) in order to selectively collapse the membrane (3) around the ports (8, 9) in the conduit section (1). The controller (23) is operative for controlling the air pressure in the chamber by selectively connecting the upstream end (10) of the conduit section (1) to the chamber and selectively bleeding air off therefrom.
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