Operation Manual

1.3 Nitrox information (O
2
information)
For dives with compressed air in normal recreational diving, nitrogen is the decisive gas for the decompres
-
sion calculations. When diving with Nitrox, the risk of oxygen toxicity rises with the increase of the fraction
of oxygen and the increase of depth and can limit dive time and the maximum depth. Smart includes this
in the calculations and displays the necessary information:
<O
2
% MIX> Fraction of oxygen: the fraction of oxygen in the Nitrox mixture can be set
between 21% (normal compressed air) and 100% in 1% increments. Your
selected mix will be the basis for all calculations.
ppO
2
max Maximum allowed partial pressure of oxygen: the higher the fraction of oxygen
in the mixture, the shallower the dive depth at which this value of the
partial pressure of oxygen is reached. The depth at which ppO
2
max. is reached
is called Maximum Operating Depth (MOD). Default setting is 1.4 bar, but it
can be set by means of SmartTRAK between 1.0 and 1.95 bar. Smart does not
display the entered ppO
2
limit, but warns the diver audibly and visually once the
depth is reached at which the ppO
2
reaches the maximum allowed value.
The CNS O
2
% value/alarm is not influenced by the selected ppO
2
max. setting.
<CNS O
2
> Oxygen toxicity: With the increased
percentage of oxygen, the oxygen in
the tissues (especially in the central
nervous system (CNS)) becomes im-
portant. If the partial pressure of oxy
-
gen rises above 0.5 bar, the CNS O
2
value increases, if the partial pressure
of oxygen is below 0.5 bar, the CNS
O
2
value decreases. The closer the
CNS O
2
value is to 100%, the closer
the limit where symptoms can occur
-> 17.
Nitrox diving may only be attempted by experienced divers after proper training
from an internationally recognized agency.
12
1 Terminology / Symbols
UWATEC
®
Smart dive computers
CNS O
2
%
increases
ppO
2
0,5 bar
CNS O
2
%
decreases
0,21 bar
WARNING