SUUNTO EON STEEL - Manual (Page 51)

Oxygen related information displayed by the dive computer is also
designed to ensure that all warnings and displays occur at the
appropriate phases of a dive. For example, the following
information is provided before and during a dive when the
computer is set in Air/Nitrox or Trimix:
• The selected O2% (and possible helium %)
• CNS% and OTU
• Audible notification when CNS% reaches 80%, then notification
when 100% limit is exceeded
• Notifications when OTU reaches 250 and then again when 300
limit is exceeded
• Audible alarm when pO2 value exceeds the preset limit (pO2
high alarm)
• Audible alarm when pO2 value is < 0.18 (pO2 low alarm)
3.23.4 Isobaric counterdiffusion (ICD)
ICD is the term used to describe the physiologic effect when the
diffusion of different gases occurs in opposite directions while
under a constant ambient pressure. Particularly in diving, the gases
are nitrogen and helium. ICD can produce the formation of bubbles
in tissues where the sum of helium and nitrogen pressures exceeds
ambient pressure. This situation may occur with trimix divers when
they change to a deco gas containing markedly less helium and
more nitrogen than the previous mix. To avoid ICD, it is advisable to
carefully plan the gas changes so that the nitrogen percentage does
not drastically increase with each change.
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