Uwatec Galileo 2, User Manual

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62
GALILEO 2 (G2) USER MANUAL
WARNING
Altitude diving with hypoxic mixes requires
proper acclimatization. Adaptation to lower
ppO
2
levels is a slow process requiring your
body to produce more red blood cells. The
adaptation time is personal and cannot be
directly calculated. Desaturation due to
pressure drop when arriving at altitude is
another factor (see chapters:
Altimeter
and
Altitude diving ).
Gas selection
In technical diving, especially with Trimix
blends, the decompression efficiency
becomes extremely important. Gas
mixes with high helium content and low
oxygen content are not well suited for
decompression.
For example, where two decompression
mixes are in most cases enough when
air or nitrox is used as a bottom gas, in
the case of trimix the optimal off gassing
requires more decompression mixes.
So, the PMG option shall be enabled
together with trimix as described in chapter:
Diving with multiple gas mixtures also
applies to trimix diving.
Tank 1 is always the starting gas from the
surface. When you have set more than one
tank, you may change gas during the dive
manually, or when the G2 suggests it.
The minimum O
2
setting for tank T1 is
18%. This is due to the limitation that a
dive must begin with gas 1. To ensure an
adequate supply of oxygen to the body,
the gas used at the beginning of the dive
must contain enough oxygen (you can use
a travel mix or one of the decompression
gases) as is required for Tank 1. Therefore,
the first alarm related to Absolute Minimum
Depth would be given at shallower than
1.2m/3.9ft.
WARNING
Heavy work while at the surface or at shallow
depths while breathing with less than
21% oxygen fraction may cause a loss of
consciousness and lead to drowning.
The minimum O
2
setting for other tanks
than tank 1 is 8%.
WARNING
Low Oxygen fraction settings may allow
greater MOD values. The dive computer cannot
evaluate your skills, experience or condition to
dive the MOD which is showing. Dive only at
depths that your certification allows.
The G2 calculates the maximum possible
helium fraction by subtracting the oxygen
fraction from 100%.
WARNING
Helium reduces the narcotic effect of the mix,
but does not remove it. At great depths, helium
may also cause an effect called “Helium
tremors” or HPNS (High Pressure Nervous
Syndrome).
The gas summary table is practical when
handling multiple gas mixtures. It can be
called up on a pre-dive check as well as
any time during the dive.