| 摘要 |
A snorkel for use by divers has the end of the tube which is uppermost when the snorkel is attached to the diver's head equipped with a valve one element of which is attached to a cap and the other valve element is incorporated in that end. The cap is buoyant when the upper end is in danger of being flooded, the valve elements then coacting to close the upper end and when the upper end is above the water level, the weight of the cap is such as to effect disengagement of the valve elements. The lower end of the tube has a valve opened when the diver exhales and a check valve above the connection of the mouthpiece with the tube is then closed. In the preferred embodiment, the cap is a loose fit on the upper end and is thus free to rock under the impact of waves then momentarily to close the valve.
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