20
4 Functions during the dive
UWATEC
®
Smart dive computers
The prescribed ascent rate must be observed at all times! Exceeding the
prescribed ascent rate can lead to microbubbles in the arterial circulation
which can lead to serious injury or death due to decompression sickness.
• In case of an improper ascent Smart Z may require a decompression stop even
within the no-stop phase because of the danger of microbubble formation.
• The decompression duration necessary for the prevention of microbubbles can
increase massively if the ascent rate is exceeded.
• From great depth a slow ascent may cause heightened saturation of tissues and
an extension of both decompression duration and total ascent time.
At shallow depth, a slow ascent may shorten the decompression duration.
• Display of the ascent rate has the priority over "CNS O
2
".
Ascent rate
Visual
alarm
Audible alarm
SPEED
SPEED
SPEED
SPEED
S
L
O
W
S
L
O
W
S
L
O
W
S
L
O
W
%
%
%
%
4.7 Partial pressure of oxygen (ppO
2 max
) / Maximum Operating Depth (MOD)
The maximum partial pressure of oxygen ppO
2 max
(default 1.4 bar) determines
the Maximum Operating Depth (MOD). Diving deeper than the MOD will expose
the diver to oxygen partial pressures higher than the set maximum level.
The MOD and consequently the ppO
2 max
can be reduced manually at Smart Z
(->18, setting the gas mixture, point 5).
In addition the maximum allowed ppO
2
can be set by means of SmartTRAK
between 1.0 to 1.95 bar.
The MOD is a function of ppO
2 max
and the mixture used. If during the dive the
MOD is reached or exceeded Smart Z sends an audible attention message,
the ascent arrow appears and the current depth display starts flashing.
Ascend to a shallower depth in order to diminish the danger of oxygen poi-
soning.
• The MOD should not be exceeded. Disregarding the warning can lead to
oxygen poisoning.
• ppO
2 max
should not be set higher than 1.6 bar.
CNS O
2
%
NO STOP
%
4 sec
WARNING
WARNING
WARNING
WARNING
Excessive ascent rates for longer periods are entered in the logbook.
Reduce ascent rate
The following ascent rates correspond to the 100% value in Smart Z.
depth (m)
<6
<12
<18
<23
<27
<31
<35
<39
<44
<50
>50
speed (m/min)
7
8
9
10
11
13
15
17
18
19
20
depth (ft)
<20
<40
<60
<75
<88
<101
<115
<128
<144
<164
>164
speed (ft/min)
23
26
29
33
36
43
49
56
59
62
66
