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5.4. Mixed gas diving
Diving with nitrox provides you with an opportunity to increase bottom times or reduce
the risk of decompression illness by reducing the nitrogen content in the gas mix.
Diving with gas mixes provides you with an opportunity to increase bottom times,
shorten decompression times, decrease the oxygen partial pressure at depth, and
reduce the risk of nitrogen narcosis or decompression illness by reducing the nitrogen
content in the gas mix.
However, when the gas mix is altered or depth increased, the oxygen partial pressure
is generally increased. This increase exposes the diver to an oxygen toxicity risk not
usually considered in recreational diving. In order to manage this risk, the dive computer
tracks the time and intensity of the oxygen exposure and provides the diver with in-
formation to adjust the dive plan in order to maintain oxygen exposure within reasonably
safe limits.
In addition to the physiological effects of enriched air on the body, there are operational
considerations to be addressed when handling altered breathing mixes. Elevated
concentrations of oxygen present a fire or explosion hazard. Consult the manufacturer
of your equipment to check its compatibility with nitrox.
5.5. Audible and visual alarms
The dive computer has audible and visual alarms that advise when important limits
are approached or that prompt you to acknowledge preset alarms. The table below
describes the different alarms and their meanings.
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