Poseidon SE7EN User Manual
Appendix 3 Page 96
Open circuit mouthpiece position (Test 43)
Test 43 (mouthpiece OC position test) is automatically passed provided the mouthpiece was
left in the OC position following the previous steps. If, for some reason, the mouthpiece is not
in the OC position when Test 43 appears on the screen, the audio alarm with two frequency
tones will activate and the text “Switch mouthpiece to Open Circuit” will appear in the informa-
tion field (Figure 2-7). The system allows the diver up to two minutes to make this switch. The
“Open-Circuit” icon will continue to display until Test 50, when the mouthpiece needs to be
switched to the closed-circuit (CC) position.
If the mouthpiece appears to be in the open-circuit position, but Test 43 does not pass, then make
sure that the mouthpiece switch is fully in the OC position. If the test still will not pass, then
make sure the HUD is positioned correctly on the mouthpiece, and is not twisted or otherwise
moved from its proper position. If no amount of repositioning of the mouthpiece lever or HUD
allows the system to pass Test 43, then contact an authorized Poseidon Service Center.
Figure 2-7.
Test 43 Switch mouthpiece to OC
position, displaying information to the
user that the mouthpiece must be placed
in the Open-Circuit position.
Tissue tension (Test 40)
As discussed in Chapter 1, the Poseidon SE7EN stores decompression data in two places:
the battery, and the main backpack computer. This allows a diver to switch to a spare battery
while maintaining decompression in the rebreather unit, or switch rebreather units and transfer
the active decompression data with the battery.
Test 40 (Tissue Tension Test) compares the stored decompression information in both the
battery and in the main backpack computer. If the two decompression states do not exactly
match exactly test 40 will fail. Failure of this test is a notification to the diver that the system
has detected this discrepancy between the two sets of decompression data. This discrepancy
will be displayed on the screen in the message area, and the diver will be prompted to acknowl-
edge the error.
IMPORTANT:
It is always best to make sure that the decompression data is
consistent between the battery and the rebreather. Confirming
a deco reset in the pre-dive routine following a failure of Test 40
will likely lead to reduced allowable dive time on the next dive
(depending on the nature of the data discrepancy).
If the change of battery is intentional the diver can confirm this by pressing the YES button, the
system will resolve the decompression difference by selecting the most conservative value for
each compartment of the decompression algorithm. If it is not intentional, the diver should
press the NO button and then re-start the pre-dive routine with the correct battery installed.
IMPORTANT:
Do NOT adjust the mouthpiece position again after completing
Test 43, until instructed to do so at Test 50. In order to complete
Test 49 (positive pressure loop test) successfully, the mouthpiece
must remain in the Open-Circuit (OC) position.
Canister Good confirmation (Test 41)
When using the SE7EN, test 41 requires the user to
confirm by the wet switch wet/dry sequence that:
A
They have a canister installed
B
It contains sufficient unused absorbent to
complete the dive.
On the M28, this becomes visible on the display
(figure 2.6C) when the question ‘Have you installed a
good Canister?’ is shown on the screen. The diver is
then prompted to select “YES” or “NO” by pressing
the appropriate button. NOTE: This test is not auto-
matic and is intended as a reminder for the diver. By confirming test 41, the diver acknowledges
that he/she has installed a canister prior to powering up the Poseidon SE7EN.
Figure 2-6C.
Test 41 (Canister Good confirmation).
