Suunto None manual Diving in Nitrox mode DIVEnitrox, Before diving in Nitrox mode, Oxygen displays

6.2. Diving in NITROX mode (DIVEnitrox)

NITROX mode (DIVEnitrox) is the second dive mode available in Suunto Cobra3 and is used when using oxygen-enriched gas mixtures.

6.2.1. Before diving in NITROX mode

If set to the NITROX mode, the correct oxygen percentage of the gas in your cylinder must always be entered into the computer to ensure correct nitrogen and oxygen calculations. The dive computer adjusts its mathematical nitrogen and oxygen calculation models accordingly. The dive computer will not accept fractional percentage values of oxygen concentration. Do not round up fractional percentages. For example, 31.8% oxygen should be entered as 31%. Rounding up will cause nitrogen percentages to be understated and will affect decompression calculations. If you want to adjust the computer to provide more conservative calculations, use the personal adjustment feature to affect decompression calculations, or reduce the PO2 setting to affect oxygen exposure according to the entered O2% and PO2 values. Calculations based on nitrox use result in longer no-decompression times and shallower maximum depths than diving with air.

As a safety precaution, the oxygen calculations in the computer are made with an oxygen percentage of 1% + set O2% .

When the dive computer is set in NITROX mode, the Dive Planning mode calculates using the O2% and PO2 values that are currently in the computer.

To set the nitrox mixes, refer to Section 5.8.3. Setting the nitrox values.

Default nitrox settings

In NITROX mode, the Suunto Cobra3 allows you to set 1 or 2 nitrox mixes containing 21-99% oxygen.

In the NITROX mode, the default setting for MIX1 is standard air (21% O2). It remains in this setting until the O2% is adjusted to any other percentage of oxygen (22% - 99%). The default setting for maximum oxygen partial pressure is 1.4 bar, however you are able to set it in the range of 0.5 - 1.6 bar.

MIX2 is set to OFF by default. To set MIX2 , refer to Section 6.2.4. Gas change and multiple breathing gas mixes. Oxygen percentages and maximum oxygen partial pressures for MIX2 are stored permanently.

6.2.2. Oxygen displays

When NITROX mode is activated, the display will show the information in the figure below. In NITROX mode, the maximum operational depth is calculated based on set O2% and PO2 values.

NITROX DIVE MODE ACTIVATION.

MAXIMUM OPERATIONAL DEPTH BASED ON

SET O2% (21%) AND PO2 (1.4 BAR) IS 56.7 M.

If set to NITROX mode, the Suunto Cobra3 will additionally show on the alternative display:

•the oxygen percentage, labeled O2%

•the set oxygen partial pressure limit, labeled PO2

•the current oxygen toxicity exposure, labeled OLF

•maximum depth

•current time

•water temperature

•dive time

•tank pressure

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