| 摘要 |
A plurality of flood prevention units are vertically stacked one over another inside a frame mounted over ventilation opening on a wall. Each unit includes a buoyant gate pivotally mounted by one or more pivotation members about a horizontal axis transverse to sidewalls of the frame for pivotation of the gate on rise of water buoyantly lifting the gate rotationally upwardly between said sidewalls for engagement with an upper deck horizontally connecting the sidewalls. A limiter limits the extent of self-actuation rotation of the gate. The gates are open during non- flooding conditions, allowing ventilation through the building opening, and sequentially close from lowest to highest on rise of water activating each gate in order, allowing ventilation to continue until the highest gate is closed. |
