Uwatec Aladin A1, User Manual

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A1 USER MANUAL
The current altitude class is shown on the
left on the bottom row and the prohibited
altitude is shown on the right. In the
example above, the diver is presently
at altitude class 2 and should not reach
altitudes above 4000m (class 4) within the
given interval of 2 hours and 30 minutes. By
increasing the interval time on the middle
row the allowed altitude increases due to
the desaturation caused by the time spent
at the current altitude class.
WARNING
If atmospheric pressure is below 610mbar
(altitude higher than 4000m/13300ft), no
decompression calculation is carried out by
the A1, and it will not start in SCUBA mode, but
in GAUGE mode. In addition, the dive planner is
not available at this altitude.
4.9.4 Decompression dives in
mountain lakes
In order to ensure optimal decompression
even at higher altitudes, the 3m/10ft
decompression stage is divided into a
2m/7ft stage and a 4m/13ft stage in
altitude ranges 1, 2 and 3.
If atmospheric pressure is below 610mbar
(altitude higher than 4000m/13300ft), no
decompression calculation is carried out
by the A1 (automatic GAUGE mode). In
addition, the dive planner is not available in
this altitude class.
4.10 Diving with Nitrox
Nitrox is the term used to describe
breathing gases made of oxygen-nitrogen
mixes with the oxygen percentage higher
than 21% (air). Because nitrox contains
less nitrogen than air, there is less nitrogen
loading on the diver’s body at the same
depth as compared to breathing air.
However, the increase in oxygen
concentration in nitrox implies an increase
in oxygen partial pressure in the breathing
mix at the same depth. At higher than
atmospheric partial pressures, oxygen
can have toxic effects on the human body.
These can be grouped into 2 categories:
1. Sudden effects due to oxygen partial
pressure over 1.4bar. These are not
related to the length of the exposure to
high oxygen partial pressure. Sudden
effects can vary and depend on the
exact level of partial pressure they
happen at. It is commonly accepted
that partial pressures up to 1.4bar are
tolerable during the active part of the
dive, and maximum oxygen partial
pressures up to 1.6bar during the
decompression.
2. Long exposure effects to oxygen
partial pressures over 0.5bar due to
repeated and/or long dives. These can
affect the central nervous system and
cause damage to lungs or to other vital
organs. Long exposures can be divided
between more severe Central Nervous
System effects and less dangerous
long-term Pulmonary Toxicity effects.
The A1 treats high ppO
2
and long
exposure effects in the following ways:
Against sudden effects: The A1 has
an MOD alarm set for a user-defined
ppO
2
max. As you enter the oxygen
concentration for the dive, the A1 shows
you the corresponding MOD for the defined
ppO
2
max. The default value of ppO
2
max
from the factory is 1.4bar. This can be
adjusted to your preference between
1.0 and 1.6bar. It can also be turned off.
Please refer to chapter:
3.3.1 Setting gas
oxygen content for more information on
how to change this setting.