92
NAUI Nitrox Diver
Tables and Charts
NOAA Oxygen Exposure Limits
PO2
(atm)
Maximum
Single Dive
Limit (minutes)
Maximum
24-Hour
Limit (minutes)
1.60 45 150
1.55 83 165
1.50 120 180
1.45 135 180
1.40 150 180
1.35 165 195
1.30 180 210
1.25 195 225
1.20 210 240
1.10 240 270
1.00 300 300
0.90 360 360
0.80 450 450
0.70 570 570
0.60 720 720
NOAA OXYGEN EXPOSURE TIME LIMITS. THE TABLE GIVES THE LIMITS
FOR A SINGLE DIVE EXPOSURE TO VARIOUS PO2 LEVELS AND FOR
EXPOSURE DURING ANY 24-HOUR PERIOD. (NOAA DIVING MANUAL,
4TH EDITION, 2001). OXYGEN PARTIAL PRESSURES BETWEEN 1.4 ATA
AND 1.6 ATA ARE SHADED.
Oxygen Percentages for Best Mix
PO2 1.2 1.3 1.4 1.5 1.6
fsw msw
40 12 40% 40% 40% 40% 40%
45 14 40% 40% 40% 40% 40%
50 15 40% 40% 40% 40% 40%
55 17 40% 40% 40% 40% 40%
60 18 40% 40% 40% 40% 40%
65 20 40% 40% 40% 40% 40%
70 21 40% 40% 40% 40% 40%
75 23 37% 40% 40% 40% 40%
80 24 35% 38% 40% 40% 40%
85 26 34% 36% 39% 40% 40%
90 27 32% 35% 38% 40% 40%
95 29 31% 34% 36% 39% 40%
100 30 30% 32% 35% 37% 40%
105 32 29% 31% 33% 36% 38%
110 33 28% 30% 32% 35% 37%
115 35 27% 29% 31% 33% 36%
120 36 26% 28% 30% 32% 35%
125 38 25% 27% 29% 31% 33%
130 40 24% 26% 28% 30% 32%
BY SELECTING THE PLANNED MAXIMUM DEPTH AND THE MAXIMUM
OXYGEN PARTIAL PRESSURE (USUALLY 1.4 ATA), THE BEST
OXYGEN PERCENTAGE FOR THE NITROX MIX IS EASILY ESTABLISHED.
ALTHOUGH PERCENTAGES HIGHER THAN 40% ARE
OBTAINED BY CALCULATION, THIS TABLE SHOWS EAN40 AS THE
HIGHEST OXYGEN MIX USED IN RECREATIONAL NITROX DIVING.