User manual
Poseidon MKVI User Manual Chapter 2 Page 46
Figure 2-12.
Test 55 – Service interval check.
Cleared to dive
Under normal circumstances the Poseidon MKVI will successfully complete all Pre-Dive checks
in about three minutes, and a screen will appear on the display that looks like that shown in
Figure 2-13, with a PO
2
value between 0.3 and 0.9 (usually the number is towards the higher
end of this range because the loop is partially lled with oxygen during Tests 49 and 53), a
depth of 0, a dive time of 0, and a remaining dive time clock showing 199 minutes.
Figure 2-14. Clear-to-dive.
At this point,the pre-dive tests are
completed, and the system is ready to dive.
Service interval check (test 55)
The nal test (Test 55; Figure 2-12) is also the simplest. This test merely ensures that the
rebreather unit does not require servicing. Each rebreather unit must be brought to a qualied
Poseidon Service Center at least once every two years, to receive updates and make any
necessary repairs or adjustments. When Test 55 is displayed, the number in the lower-right
corner of the screen (adjacent to the small clock icon) indicates the number of weeks remaining
before servicing will be required. When this value gets low, return the rebreather to an authorized
Poseidon service center for maintenance. Upon passing Test 55, the pre-dive routine is complete.
Once the service date is due, the diver is prompted to acknowledge (similar to “power up proce-
dure”) that he/she has understood that service is needed. A grace period of 4 weeks is added.
The service due date can also be seen through the PC Cong PC software.
Pre breathe
Figure 2-13. Pre breathe.
Open circuit regulator function (test 54)
After completing test 53, the letters “OC” ash in the upper-left corner of the screen along with
the Open-Circuit Bailout icon, indicating the need change the mouthpiece back to OC mode.
When the mouthpiece is switched, the word “bREAtHE.” scrolls across the two PO
2
value
digits in the upper-right corner of the screen. This prompts the diver to test the function of the
open-circuit regulator. After inhaling several breaths from the regulator, the test passes.
One second or directly after pre-dive has completed, the diver will be prompted to perform a
prebreathe. This is done by ashing ‘Pbr’ in the CRA eld. The remaining prebreathe time
appears in the depth eld. When the user switches the mouthpiece to CC mode, the remaining
prebreathe counter will count down from 300 seconds. If the user switches out of CC then the
counter will pause. Once the counter has counted down to zero, the rig enters ready to dive
mode. It will stay in this state for 30 minutes. If the dive is not started in this time, then it goes
back to prebreathe mode. Prebreathe mode is not mandatory and can be terminated without
penalty by starting the dive. 30 minutes after the end of a dive then the rig will once again enter
prebreathe mode. Note that during prebreathe mode, the rig will re the diluent and oxygen
solenoids for 2 seconds close to the start of each prebreathe session, if the diver is not breathing
from the loop at this stage the unit may issue an alarm.
The reason for using the solenoids at this stage is that if a diver have turned off their cylinders,
this will result in a big pressure drop which should will prompt the diver to turn the cylinder on. If
a closed cylinder is detected during pre breathe then the requisite bar graph will ash.