Owner`s manual

Dive Rite
Ch. 5 Pg. 2
Copyright, Dive Rite All Rights Reserved January 2009
The following chart lists the limits as established by NOAA.
2
NOAA O EXPOSURE LIMITS
Oxygen
Partial
Pressure
2
(PO )
Maximum
Single
Exposure
Maximum
Daily
Exposure
( ata ) (min) (hrs) (min) (hrs)
1.6 4 5 0.75 150 2.5
1.5 120 2.0 180 3.0
1.4 150 2.5 180 3.0
1.3 180 3.0 210 3.5
1.2 210 3.5 240 4.0
1.1 240 4.0 270 4.5
1.0 300 5.0 300 5.0
0.9 360 6.0 360 6.0
0.8 450 7.5 450 7.5
0.7 570 9.5 570 9.5
0.6 72 0 12.0 720 12 .0
Percentage of Oxygen Toxicity
The Percentage of Oxygen Toxicity concept was developed to permit a simple application of
the Oxygen partial pressure limits chart. To calculate the percentage of Oxygen toxicity, look
up the partial pressure of Oxygen on the Oxygen Partial Pressure Limits chart and divide 100
by the maximum number of minutes allowable at that dosage. This will give the percentage of
2
the total limit each minute is worth. This procedure can be performed for either a fixed fO or
2
a fixed PO .
Open Circuit divers need to calculate their exposure at multiple depths and add up the
2
individual exposures because the PO varies with depth, but CCR divers generally use a single
set-point for “bottom” portion of a dive so only total time needs to be considered.