No-decompression time limits (mins) for various depths (ft) for the first
dive of a series
Personal Mode / Altitude Mode
Depth
(ft)
P2/A2
P2/A1
P2/A0
P1/A2
P1/A1
P1/A0
P0/A2
P0/A1
P0/A0
5
4
4
3
6
5
4
4
8
6
5
4
6
5
4
4
8
6
5
4
9
7
6
5
8
6
5
4
9
7
6
5
10
9
7
6
120
130
140
150
9.2.3. Altitude diving
The atmospheric pressure is lower at high altitudes than at sea level. After traveling to a
higher altitude, you will have additional nitrogen in your body, compared to the equilibrium
situation at the original altitude. This "additional" nitrogen is released gradually over time
and equilibrium is restored. It is recommended that you acclimatize to a new altitude by
waiting at least three hours before making a dive.
Before high-altitude diving, the instrument must be set to the Altitude Adjustment mode
to adjust the calculations for the new altitude. The maximum partial pressures of nitrogen
allowed by the mathematical model of the dive computer are reduced according to the
lower ambient pressure.
As a result, the allowed no-decompression-stop limits are considerably reduced.
9.3. 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. For example:
•
the displayed oxygen exposure calculations are raised to the next higher percentage
value
•
for recreational scuba diving, the recommended upper limit of 1.4 bar PO
2
is used as
a default
•
the CNS % limits up to 1.6 bar are based on 1991 NOAA Diving Manual limits
•
the OTU monitoring is based on the long-term daily tolerance level and the recovery
rate is reduced
Oxygen related information displayed by the dive computer is also designed to ensure
that all warnings and displays occur at the appropriate phases of a dive. For example, the
following information will be shown before and during a dive when the computer is set in
NITROX mode:
•
the selected O
2
% on the alternative display
•
OLF% alternative display for either CNS% or OTU% (whichever is larger)
•
audible alarms are given and the OLF value starts to blink when the 80% and 100%
limits are exceeded
•
audible alarms are given and the actual PO
2
value blinks when it exceeds the preset
limit
•
in dive planning, the maximum depth according to the O
2
% and maximum PO
2
selected
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