| 摘要 |
<p>Breathing apparatus is provided for use under water which comprises a connection device such as a helmet, mask, or the like and a breathing circuit in communication with the connection device. The breathing circuit includes a carbon-dioxide absorber and an expansible gas chamber, and, in operation, provides a first operating period wherein the breathing circuit is closed and a breathing gas is caused to circulate in the breathing circuit until the oxygen concentration of the circulating breathing gas is reduced to a predetermined value and a second operating period, which alternates with the first, wherein the used breathing gas is released to ambient and a fresh gas, the quantity of which is substantially independent of the depth of the user under the water surface, is applied to the breathing circuit. To compensate for a change in floating capacity resulting from a decrease in the volume of the expansible gas chamber caused by an increase in the diving depth, a valve is disposed in a connection between a fresh-gas container and the breathing circuit, the valve being controlled responsive to the pressure of the ambient environment to cause release of further fresh gas from the fresh gas container when the diving depth is increased.</p> |
