Hollis Explorer User Manual - page 44
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In general, Oxygen and CO
2
sensors do not drift excessively. Constant cal-
ibration (every dive) is not required. Periodically check sensors and keep
them dry between dives if possible and especially during storage.
WARNING: Use calibration sparingly, not as a routine task that
may mask other potential problems.
CONDUCTING AN O
2
SENSOR CALIBRATION
During the Pre-dive sequence you have the option to calibrate the oxygen
and CO
2
sensors from the Calibration screen (Fig. x.x). Selecting O
2
, will
display another series of screens that will guide you through the calibra-
tion. Please see descriptions later in the manual for calibrating the CO
2
sensor.
SUMMARY OF DO’S AND DON’TS
OF OXYGEN SENSOR CALIBRATION
When calibrating sensors there are two factors that the EX-
PLORER takes into account:
1. Ambient pressure
2. Ambient AIR oxygen content
These two factors multiply to determine the partial pressure of
the oxygen exposed to the Oxygen sensor.
Example:
20.9% oxygen at 1000mBar = 0.209mBar partial pressure of
oxygen
20.9% oxygen at 750mBar = 15.675 mbar partial pressure of
oxygen
The EXPLORER uses ambient air as the calibrating gas, because
its composition is accurately known. This is in contrast to say a
cylinder of compressed oxygen that can vary from supplier to
supplier, as well as around the world, from at least 94% to 100%.
!