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M2 USER MANUAL
4.9.7
Enabling the CCR mode
When the CCR mode is activated, the
normally changeable open circuit gases
(Gas 1 and Gas 2) are converted to ppO
2
setpoints (SP1, SP2).
The dive start setpoint (SP1) has a selectable
range from 0.3 up to 0.95bar ppO
2
. The
bottom setpoint (SP2) has a range from
1.0 up to 1.4bar ppO
2
and this is switched
normally active on the way to the bottom or
when the bottom depth is reached.
The SP switch depth is suggested by
the dive computer the same way the gas
switches are suggested in open circuit
mode (predictive gas switching).
The switch points are determined by the
equivalent oxygen contents in open circuit
mode. So, the SP1 changes on the way
down when the equivalent content of the
gas at that depth reaches the 21% O
2
level.
For example, with a SP1 of 0.5bar the depth
would be approximately 13.8m in salt water.
D
ept
h
Time
Bottom mix
Deco mix
Diving with 2 gas mixtures
D
ept
h
Time
Diving with CCR
Switch depth between SP1/SP2
SP1
SP1
SP2
SP2
4.10 Altitude diving
4.10.1 Altitude classes, altitude
warning and NO-FLY time
after a dive
Gaining altitude is similar to starting an
ascent from a dive: you expose your body
to a lower partial pressure of nitrogen and
consequently you start off-gassing. After
a dive, given the higher nitrogen loading
in your body, even reaching an otherwise
negligible altitude can potentially cause
decompression sickness. Consequently,
the M2 constantly monitors the ambient
pressure and uses it to evaluate your
nitrogen loading and off-gassing. If the
M2 notices a drop in ambient pressure
not compatible with your current nitrogen
loading, it will activate a warning to alert
you of the potentially dangerous situation.
If you have remaining desaturation on the
M2, you can view the current situation by
selecting the dive menu.
The desaturation text and remaining count-
down time are shown on the middle row.
The no-dive symbol and count-down timer
are shown on the bottom row to indicate the
period when you should not have another
immersion due to possible microbubbles,
high CNS or excessive nitrogen loading in
your body.
By pressing the SEL button the following
page shows the NO-FLY symbol, with the
count-down time on the bottom row, until
the restriction is completed.
The interval from the last dive is shown on
the middle row with the text INT.
Acceptable altitudes are shown on the
first page of the planner menu. Prohibited
altitudes (altitudes the M2 has computed to
be incompatible with your current nitrogen
saturation levels) are levels above the
second altitude on the display. Please read
section
Altitude and the decompression
algorithm
for more details.
The current altitude and altitude class can
be read on the altitude meter menu: ALTI.
F
NOTE:
The NO-FLY, no-dive and
altitude restriction symbols are also
shown on the time of day display
when applicable
.
Summary of Contents for M2
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