User manual
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ALADIN SQUARE USER MANUAL
2.2.2 Altitude and the decompression algorithm
Atmospheric pressure is a function of altitude and of weather conditions. This is an important
aspect to consider for diving, because the atmospheric pressure surrounding you has an
infl uence on ongassing and offgassing of nitrogen. Above a certain altitude, the decompression
algorithm has to change in order to account for the effect of the change in atmospheric pressure.
Square divides the possible altitude range in 5 classes that are illustrated on the picture below:
The altitude classes are defi ned in terms of
approximate elevations because the effect
of weather conditions can make the switch
point pressure occur at different levels.
WARNING
At altitude class 4 Square functions in gauge mode
only (automatic switch from computer mode).
NOTE: You can check your current
altitude class and elevation by
activating the altitude meter. Refer to
chapter Checking the Altitude on
how to do so.
NOTE: Square deals with altitude
automatically: it monitors the
atmospheric pressure every 60
seconds and if it detects a suf cient
drop in pressure, it does the following:
it shows the new altitude range
at altimeter and, if applicable, the
prohibited altitude range at desat
screen; it indicates the desaturation
time, which in this case is an
adaptation time to the new ambient
pressure. If a dive is started during this
adaptation time, Square considers it
a repetitive dive, since the body has
residual nitrogen.
2.2.3 Prohibited altitude
Going to altitude, as well as fl ying after diving,
exposes your body to a reduced ambient
pressure. In a way similar to the no-fl y time,
Square advises you which altitudes are safe
to reach after a dive and which aren’t. If you
have to drive over a mountain pass to return
home after a dive, it can be quite important
to have this information.
The prohibited altitudes are the ones above
the elevation displayed at desat display. In
the example above, the diver should not
reach altitudes of greater than 4000m.
Square has an altitude warning: if you
were to reach an altitude that according to
Square is incompatible with your current
residual nitrogen levels, it will warn you with
an altitude warning.