5.4. Nitrox
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.
However, when the gas mix is altered, the oxygen content of the mix 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 information 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.
Table 5.1. Audible and visual alarm types
Alarm type | Alarm reason |
Short single beep | Dive computer is activated. |
Dive computer automatically returns to the TIME mode.
Three beeps with a three second interval
Three beeps with a three second interval and activated backlight
Continuous beeps and activated backlight
Cylinder pressure reaches 50 bar/725 psi. The cylinder pressure display will start to blink.
Cylinder pressure reaches the selected alarm pressure.
Calculated remaining air time reaches zero.
Maximum allowed ascent rate, 10 m per min/33 ft per min, is exceeded. Ascent rate bar graph blinks and STOP warning appears.
Decompression ceiling depth is exceeded. An error warning Er and a downward pointing arrow appear. You should immediately descend to, or below, the ceiling. The instrument will otherwise enter a permanent Error mode within three minutes, indicated by a permanent Er.
You can set alarms for maximum depth, dive time and tank pressure. See also Section 5.8. DIVE mode settings and Section 4.1. TIME mode settings.
Table 5.2. Preset alarm types |
|
Alarm type | Alarm reason |
Continuous beep series for 24 seconds
Maximum depth blinks as long as the current depth value exceeds the preset value.
Continuous beep series for 24 seconds or until any button is pressed.
Dive time blinks for one minute.
Preset maximum depth has been exceeded.
Preset dive time has been exceeded.
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