Operation Manual
English
21
4  Functions during the dive
UWATEC
®
 Smart dive computers
III
4.8 Oxygen toxicity (CNS O
2
%)
Smart Z calculates oxygen toxicity from depth values, time and the gas mixture
and displays it in the location of the ascent rate. The toxicity is expressed in 1% 
increments of a maximum tolerated value (O
2
 clock). The symbol "CNS O
2
" is  
displayed together with the percentage.
An audible attention signal goes off if oxygen tox
-
icity reaches 75%. The symbol "CNS O
2
" flashes 
and the ascent arrow appears. 
Ascend  to  shallower  depth  to  decrease  oxygen 
loading.
  When  oxygen toxicity  reaches 100%,  an audible 
alarm  goes  off  every  4  seconds.  "CNS  O
2
",  the 
precentage  value  and  the  ascent  arrow  flash. 
Danger of oxygen toxicity!
  Start ascent at once.
• During an ascent and if the CNS O
2
% value does not increase anymore (due to 
a lower partial pressure of oxygen), the audible warning is suppressed.
• During the ascent, the display of the oxygen toxicity is replaced by the ascent 
rate. If the ascent is stopped, the display changes back to the indication of the 
CNS O
2
% value.
• Smart Z will display CNS O
2
% values exceeding 199 % with 199 %.
4.9 Tank pressure        The  tank  pressure is  also  used  for  the  calculation  of 
the remaining bottom time (RBT) and the workload.
  When the tank pressure reaches the set warning 
pressure  (SmartTRAK)  an  audible  alarm  goes  off 
and  the  tank  symbol  is  shown.  Default  value  of 
warning pressure: 100 bar (1450 psi)
  Do not dive any deeper. Start to ascend soon.
  In  case  of  increased  workload,  Smart  Z  displays 
a lung  symbol and an  audible alarm goes  off. 
(The sensitivity of workload can be changed with 
SmartTRAK).
  In  order  to  prevent  additional  saturation,  reduce 
exertion, relax and breathe more slowly.
  If  Smart  Z  receives  no  data  for  30  seconds, 
an audible alarm goes  off and  the transmitter 
warning appears.
If Smart Z does not receive pressure data for another 40 seconds, it will acti
-
vate another audible alarm. RBT and transmitter warning will no longer be 
displayed. Instead of the tank pressure value Smart Z will display "- - -".
Check the position of transmitter and Smart Z. Start ascending at once. 
Smart Z will switch back to its normal display as soon as new data is received.
  If the tank pressure is lower than 14bar/200psi the 
transmitter  switches  off  and  Smart  Z  will  display 
"---". 
  Do not  let the tank pressure drop below 14bar  / 
200psi.
CNS O
2
%
NO STOP
%
CNS O
2
%
NO STOP
%
4 sec
CNS O
2
%
NO STOP
%
%
%
4 sec
4 sec
Transmitter warning 
%
4 sec
%
If tank pressure 
<14 bar/200psi
WARNING
WARNING
WARNING
WARNING
WARNING
WARNING
Oxygen toxicity










