6.3. OXYGEN EXPOSURE

The oxygen exposure calculations are based on currently accepted exposure time

limit tables and principles. In addition to this the dive computer uses several

methods to conservatively estimate the oxygen exposure. These include for

example:

• the displayed oxygen exposure calculations are rounded to the next

higher whole percentage value

• for recreational scuba diving, the recommended upper limit of 1.4 bar

is used as a default

• the CNS% limits up to 1.4 bar are based on 1991 NOAA Diving Man-

ual limits, but the limits higher than 1.4 bar are signiﬁ cantly shortened.

Thus, if through carelessness or emergency you exceed the 1.4 bar PO

limit, the dive computer will still continue to calculate and show OLF%

information

• the uptake and recovery for both CNS% and OTU% are monitored

• the OTU monitoring is based on the long-term daily tolerance level and

the recovery rate is reduced

• the half time limit for the CNS recovery is 75 minutes

• the maximum depth warning limit based on 1.4 bar PO

is calculated

and displayed. If extra conservatism for the depth limits is required the

can be adjusted to 1.2 or 1.3 bar.

Oxygen related information displayed by the dive computer is also designed to

ensure all warnings and displays in the appropriate phases of a dive. E.g. the fol-

lowing information will be shown before and during a dive:

• the adjusted O

• the color-coded OLF% bar graph for both CNS% and OTU% monitor-

ing

• audible alarms are given and the OLF bar graph starts to blink when the

80% and 100% limits are exceeded

• the blinking of the bar graph stops, when the PO

is below 0.5 bar

• the PO

is shown when it is greater than the preset limit.