| 摘要 |
A flood prevention device (1), for example an automatically closing air brick. The device (1) comprises: a body (2) having an outer side (3) and an inner side (4) having at least one opening (5), at least one channel formed through the body (2) between the outer side (3) and the at least one opening (5) of the inner side (4), and a valve (6) comprising a flap (7) and a buoyancy structure (10). The flap (7) is pivotally mounted to the body (2) and has an outer side and an inner side. The flap (7) has an open position in which gas is permitted to flow through the channel and a closed position in which the flap (7) is pivoted from the open position to seal the channel. The buoyancy structure (10) is formed on an outer side of the flap (7) such that the valve (6) is buoyant on water and if the outer side of the flap (7) is exposed to a rising liquid level the centre of buoyancy of the valve (6) is always located outwards of the flap (7) and the buoyancy structure (10) will act to move the flap (7) from the open position to the closed position. According to a first aspect of the invention the lowermost part of the opening (5) is formed at a height greater than a minimum height of liquid level at which the flap (7) will be moved to the closed position. According to a second aspect of the invention the buoyancy structure (10) may be an air chamber that is open on a lower side, such that when the liquid level rises above the horizontal centre line of the flap (7) gas (12) contained within the air chamber is compressed thereby providing a positive pressure on the valve (6) to keep the valve closed. |
