Hollis Explorer User Manual - page 28
22 |
AUTOMATIC TURN ON
FAILSAFE FEATURE
Normal practice and training is for the user to turn the EXPLORER on by-
hand and go through the pre-dive checks. The following failsafe additions
are to reduce diver error, where the EXPLORER is turned off prior to breath-
ing on the unit. The basis for the auto-breathe software is to reduce the
chance of accidental injury or death by breathing on an EXPLORER that is
in off/sleeping state.
EXPLORER uses detection of a diver breathing the unit to automatically
turn the unit on.
BREATHING DETECTION TURN ON RULES
The EXPLORER will turn on if PPO
2
drops to 0.17bar. Therefore even with
the unit incorrectly assembled (gas not turned on), the system will detect
the fall in PPO
2
and will activate. It will then alarm and force the user to
properly complete the pre-dive sequence.
Once turned on the unit will attempt to maintain a breathable PPO
2
based
on the DCP (Dive Control Parameter) setting and the supply gas expected.
If sensors are removed or read 0.00 then the unit will only turn on with
depth or by the user pressing a switch. This feature is included to conserve
battery power when the user takes out PPO
2
sensors for storage or during
transport. Other current rebreather designs and CE approvals require a
reduced safety margin than achieved even with this power save scenario.
In other words, the chance of the user taking out the sensors and acciden-
tally not turning the unit on before breathing falls into user set-up error that
should not routinely occur due to training and a good pre-dive check re-
gime. Other errors such as failing to turn on cylinders, etc. are much more
likely, and should be reduced by proper training and the intelligent alarm
systems as in the EXPLORER.
If the diver does not have HP gas turned on, alarms on the HUD (forwards
and rear facing HUD) and Primary display will occur as soon as auto turn-
on occurs. Hence this method provides increased warnings whenever loop
PPO
2
is breathed when the unit is off.