Valves in oxygenrebreathers operated by a demand valve
In addition to the principle of dosing gas by activating a valve with a lever, we also know the on-demand principle. On the counter-lung, an automatic device (second stage principle) is mounted whereby a membrane operates a valve instead of a lever. This valve opens and will supply oxygen until the pressure in the counter-lung increases and the membrane relieves the pressure. The gas supply then stops. In practice, this means that in oxygen systems, as soon as the volume decreases and the diver inhales due to the under pressure, the valve will be activated.
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