User manual

Poseidon MKVI User Manual
Appendix 2
Page 86
4. Pre-Dive Procedures with a MKVI enabled for
Decompression Diving
It is possible to determine whether a rig is congured for decompression diving by examining
the ceiling indicator during the pre-dive routine. The ceiling indicator will be blank for a standard
rig and will ash for a MKVI enabled for decompression diving.
48m/60m Deco Trimix
On a unit with the blue Deco 48m Trimix or white Deco 60m Trimix battery installed, the diver will be
prompted to conrm the helium fraction (pre-dive test 51) and O2 fraction (test 52) of the diluent
mixture. This test occurs immediately after the mouthpiece ‘CC’ test (test 50), and will occur only if the
MKVI is congured for decompression diving, or if the congured diluent is not air (the test is not per-
formed if the rig is not congured for decompression diving and the diluent is already congured as air).
The rig will display ‘HE’ ‘Fr’ ‘nn’ or ‘O
2
’ ‘Fr’ ‘nn’ in succession in the PO
2
eld, where ‘nn’ is the
assumed helium or oxygen fraction in the diluent. The diver will have to acknowledge this by going
through the standard wet/dry sequence (see chapter 2, Electronics Power-Up, in the MKVI
manual). If the helium or oxygen fraction is incorrect, the diver can either:
1. Use the IrDA link to change it to the correct value. The new value will appear in the LCD.
2. Let the test timeout (two minutes) at which point the rig will shut down.
Figure A2-8: Helium conrmation screens
at test 51, showing the alternating values
of “HE” (for “Helium”; top), “Fr” (for
“Fraction”; middle), and a numeric value
(indicating the assumed fraction of Helium;
bottom) for the diluent mixture.
Figure A2-9: Oxygen conrmation screens
at test 52, showing the alternating values
of “o2” (for “Oxygen”; top), “Fr” (for
“Fraction”; middle), and a numeric value
(indicating the assumed fraction of
Oxygen; bottom) for the diluent mixture.
5. Switching batteries
If a rig has been congured with a gas mixture other than air on a MKVI using a Deco 48m or
60m battery, and then a 40m Deco battery or Recreational 40m battery is then inserted into
the rig, the user will be given a special prompt during the pre-dive to conrm that diluent will
be automatically changed to air.
Procedure
After inserting a Recreational 40m or yellow Deco 40m battery into a MKVI that was previously
congured for non-air diluent (e.g., trimix), the pre-dive routine will display tests 51 and 52 as
described above for the user to conrm and acknowledge that the diluent will be air (0%
Helium, and 21% oxygen). If these tests are completed successfully, the unit will automatically
switch the diluent composition to air. If the Recreational 40m battery or Deco 40m battery was
inserted by mistake, the diver should NOT conrm these tests. Instead, the test should be
allowed to time out (two minutes) after which the rig will power-down, and then the correct
(Deco 48m/60m) battery can be inserted. In this case, the original non-air diluent will be retained.