Hollis Explorer User Manual - page 62
56 |
CALIBRATION
During the Pre-dive sequence you are prompted if you want to calibrate
the CO
2
sensor (Fig. 3.24).
The
ONLY source of calibration gas is fresh air. With the filter removed
and the sensor in fresh air the CO
2
reading should read 0.4mb +/-
0.1mb. Leave the sensor exposed for at least 5 minutes. The on-screen
prompts will guide you through the calibration. This involves removing the
exhale hose from the mouthpiece and breathing the unit for one minute to
circulate fresh air into the system.
WARNING: At the end of a Pre-dive sequence with a new filter
fitted the CO
2
readings should be almost 0mb. If this is not the
case then the sensor must be recalibrated (as above) or re-
placed.
NOTE: Post dive, if you want to do another calibration, you
must remove the filter cap to calibrate.
The same system should be used to just check the calibration. There is no
need to constantly calibrate but it is good practice to check the calibration
at the start of a dive sequence using the above method.
Once it is calibrated, to confirm the operation, gently breathe across the
sensor face until the reading changes. Now re-install the filter prior to div-
ing.
After calibration and with the sensor inserted into the loop if a full pre-
breathe with fresh absorbent is undertaken the CO
2
reading should fall to
0mb. This is normal.
Post dive and with no gas flow (breathing) you may see a small rise in CO
2
levels due to gas density and pocketing. After a pre-breathe this should
stabilize. Blowing into the sensor face may also create the same affect until
it is used again normally in the breathing loop.
WARNING: If at anytime you see a reading that is abnormal you
should check the calibration.
Fig. 3.24
!
!