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3.19
Diving at altitude
! W
ARNING: Diving at high altitude requires special knowledge
of the variations imposed upon divers, their activities, and their
equipment by the decrease in atmospheric pressures. Hollis recommends completion of a specialized Altitude training course by a
recognized training agency prior to diving in high altitude lakes or
rivers.
The Explorer is fitted with a digital depth sensor. For it to accurately gauge
altitude and preceding dive depths, the Explorer must be turned on prior
to diving. This is the normal process as a predive must be conducted. It
becomes especially important if you have transported the Explorer to a
change in surface altitude.
LOW PO2 SAFETY TURN ON & INJECTION
The Explorer has a safety feature that will cause an activation and attempted nitrox injection to raise the PO2 in the breathing loop if the LSS detects
a drop of PO2 to a level of 0.17 or below. This is an attempt by the system
to prevent a hypoxic condition in the breathing loop.
It is important to understand and remember from your training that with an
increase in altitude (decrease in ambient pressure) the PO2 of ambient air
will drop. Regardless, of a constant FO2 of 0.21 the PO2, what the oxygen
sensors measure, may drop to or below 0.17. This would occur above
5,000 ft/1,524 m of altitude.
To avoid accidental activation during transport, either remove the oxygen
sensors or add sufficient nitrox to the loop. Upon reaching altitude reinstall the sensors and check the calibration as a part of the normal predive
sequence.
For clarity, the Explorer can be oxygen calibrated in air at any altitude. To
register the correct dive depths at any altitude the Explorer must be turned
on at the intended dive site altitude to establish a correct surface pressure
reading.
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