NAUI Nitrox Diver
26 Gases & Gas Mixtures
Oxygen Partial Pressure (in atmospheres absolute) at Depth
FO2 Air 0.24 0.26 0.28 0.30 0.32 0.34 0.36 0.38 0.40
Depth
(fsw)
Depth
(msw)
40 12 0.46 0.53 0.58 0.62 0.66 0.71 0.75 0.80 0.84 0.88
50 15 0.53 0.60 0.65 0.70 0.75 0.80 0.86 0.91 0.96 1.01
60 18 0.59 0.68 0.73 0.79 0.85 0.90 0.96 1.01 1.07 1.13
70 21 0.66 0.75 0.81 0.87 0.94 1.00 1.06 1.12 1.19 1.25
80 24 0.72 0.82 0.89 0.96 1.03 1.10 1.16 1.23 1.30 1.37
90 27 0.78 0.89 0.97 1.04 1.12 1.19 1.27 1.34 1.42 1.49
100 30 0.85 0.97 1.05 1.13 1.21 1.29 1.37 1.45 1.53 1.61
110 33 0.91 1.04 1.13 1.21 1.30 1.39 1.47 1.56 1.64 1.73
120 36 0.97 1.11 1.21 1.30 1.39 1.48 1.58 1.66 1.76 1.85
130 40 1.19 1.28 1.38 1.48 1.58 1.68 1.77 1.88 1.98
FIGURE 2-9: OXYGEN PARTIAL PRESSURE AT DEPTH FOR VARIOUS NITROX BLENDS–MODERATE SHADING INDICATES AN OXYGEN PARTIAL
PRESSURE BETWEEN 1.4 AND 1.6 ATA. DARK SHADING INDICATES OXYGEN PARTIAL PRESSURE IN EXCESS OF 1.6 ATA.
DETERMINING OXYGEN PARTIAL PRESSURE BY
TABLE
Using Figure 2-9, to find the oxygen partial pressure
for a nitrox mixture, move along the top row to the
oxygen fraction of the mix. Then move down that column
to the row of the desired depth. If the exact mix or
the exact depth is not shown, round up to the next higher
value.
THE OCEANX CALCULATOR
Another tool that can be used to determine oxygen
partial pressures, as well as several other useful values,
such as equivalent air depth, is the OCEANx calculator.
With the oxygen percentage set on the OCEANx calculator,
values for depth and oxygen limits are displayed in windows.
The use of the OCEANx calculator will be presented
in Chapter 4: Choosing the Best Nitrox Mix.