Aqua Lung i550C, Owner'S Manual

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Doc. 12-7909-r04 (10/31/18)
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DIVE FEATURES
© Aqua Lung International, Inc. (2018)
DTR (DIVE TIME REMAINING)
The i550C constantly monitors No Decompression status and O2 Accumulation, and will display whichever time is
the least amount available as DTR on the No Decompression Dive Main screen. The time being displayed will be
identified by the NO DECO or O2 MIN icons.
NO DECOMPRESSION
No Decompression is the maximum amount of time that you can stay at your present depth before entering De-
compression. It is calculated based on the amount of nitrogen absorbed by hypothetical tissue compartments. The
rates each of these compartments absorb and release nitrogen is mathematically modeled and compared against
a maximum allowable nitrogen level.
Whichever compartment is closest to this maximum level is the controlling compartment for that depth. Its result-
ing value (NO DECO) will be displayed as DTR. It will also be displayed graphically as the N2 Bar Graph, see Bar
Graphs below.
As you ascend, the N2 Bar Graph segments will recede as control shifts to slower compartments. This is a feature
of the decompression model that is the basis for multilevel diving, one of the most important advantages that Aqua
Lung dive computers offer.
O2 MIN (OXYGEN TIME REMAINING)
When set for nitrox operation, O2 SAT (Oxygen Saturation) during a dive is displayed on an ALT screen as a
percentage of allowed saturation identified by the O2 SAT icon. The limit for O2 SAT (100%) is set at 300 OTU
(Oxygen Tolerance Units) per dive or 24 hour period. See the chart at the back of this manual for specific times
and allowances. O2 SAT and O2 MIN values are inversely related; as the O2 SAT value increases the O2 MIN
value decreases.
When the O2 MIN value becomes less than the No Decompression calculations for the dive, DTR (Dive Time
Remaining) will be controlled by O2 SAT and the O2 MIN value will be displayed as the DTR on the Dive Main
screen, identified by the O2 MIN icon.
DTR is NO DECO
% O
2
Saturation
DTR is O2 MIN
ALT 2 DIVE MAIN
BAR GRAPHS
The i550C features two specific bar graphs.
1. The one on the left represents ascent rate. It is referred to as ASC Bar Graph.
2. The one on the right represents nitrogen loading. It is referred to as the N2 Bar Graph.
Ascent Rate
Nitrogen Loading