Cns Toxicity Display - Cressi ARCHIMEDE Manuel D'instructions

Within the first 10 minutes of surface interval, you cannot
enter the ( ) screen to change the parameter settings,
hence you cannot change the previously set oxygen fraction
2 After a 10 minute surface interval, the computer resets
the FO2 fraction at a safety value of 99%, until the diver
resets the correct fraction value for the new Nitrox supply.
"--" will be displayed as in (fig. 17). Obviously, the new
Nitrox supply will have to be checked by the diver before
setting the proper Oxygen fraction in the dive computer.
This situation is indicated on the UFDS display by the (
icon, which blinks on the main screen in order to draw your
attention to the need to reset the parameters before diving.
This is a very simple procedure, as previously explained in
Chapter 2.3.
If you happen to forget to reset the new FO2 value, owing to
the automatic reset at 99%, when reaching a depth of just
12ft (with 1.4 P02), the PO2 alarm will warn you accordingly
(fig. 18). The diver could then return to the surface and reset
the correct value. Conversely, if he/she decides to continue
the dive, a second PO2 alarm will be released at 1.6 bar (e.g.
at 19.7ft).
3 Should you set the FO2 value and then take no dive com-
puter will store this value until midnight of the same day,
and will then reset the default value (F02=99%).
Related topics:
• 2.3.1. - Dive Parameter Setting.
• 3.5. - CNS Toxicity Display.
• 3.6. - PO2 Alarms.
• 4.1.1. - Surface Interval Time.

3.5. - CNS Toxicity Display

The Archimede Cressi Sub dive computer gives you a graph-
ic display of the degree of Central Nervous System oxygen
poisoning, which is linked to Partial Oxygen Pressure as well
as to the diver's exposure time to high Partial Oxygen
Pressure (PO2). Figure 19 shows the column formed by 8 pix-
els on the UFDS display indicating the accumulated oxygen
amount. When all eight pixels are illuminated on the display, it
means that the maximum admissible CNS tolerance has
been reached and that you are in serious danger of oxygen
)
Nitrox
poisoning (hyperoxia).
It is important that constant monitoring of this information is
extremely important. Being a function of Partial Oxygen
Pressure and of exposure time, it requires constantly moni-
tored when diving.
In order to lower the risk of hyperoxia, Archimede considers
all relevant data keeping into account the time and intensity
of exposure to oxygen. When the oxygen level reaches
threshold values, close to maximum admissible toxicity (e.g.
when 7 out of 8 pixels are illuminated), the graph bar begins
to blink and an audible alarm will be released for 15 seconds,
thus warning the diver about the high risk of CNS intoxication
(70% alarm).
When also the 8th pixel is turned on, a second (100%) audible
alarm will be triggered and the graph bar will start to blink until
you start your ascent in order to reduce Partial Oxygen
Pressure. The graph bar will stop blinking only when the 8th pixel
turns off. The alarm will in any case be recorded in the Logbook.
NOTA: Exposure calculation result is rounded to the high-
er percentage value.
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