Poseidon SE7EN User Manual
Appendix 3 Page 97
Figure 2-8.
Tests 44 and 45, confirming sufficient gas supply pressures.
DANGER:
Always open the oxygen cylinder valve slowly. Rapid pressurization
increases risk of fire. Opening the valve slowly reduces this risk.
Carefully maintaining clean oxygen regulators, cylinders, and valves
before, during, and after your dives will further reduce this risk.
WARNING:
Once both cylinders have been turned on during Tests 44 and 45,
do NOT turn them off again until after completing the dive. If they
are turned off before completing the pre-dive routine, then Tests
49 and/or 53 will fail. If they are turned off before the dive, the dive
will be cut short. This is particularly true for the diluent cylinder,
which provides breathing gas in the event of an emergency open-
circuit bailout.
Oxygen and diluent cylinder supplies (Test 44 & 45)
Tests 44 and 45 determine whether the Oxygen and Diluent cylinders, respectively, are turned
on and have sufficient gas to conduct a dive. Following proper procedure, both cylinders will have
been in the off position when Test 44 is reached (if not, gas will be wasted during Tests 24–27,
which verify that the four solenoid valves draw the correct amount of power when held open).
Each of these two tests will allow up to two minutes to turn on each cylinder. The bottom one,
two, or three segments of the respective cylinder pressure bar graphs will flash until sufficient
pressure is detected (Figure 2-8). When the system detects sufficient oxygen pressure, it then
waits until it detects sufficient diluent pressure. Provided the oxygen cylinder pressure is
greater than 34 bar / 493 psi, and the diluent pressure is greater than 51 bar / 739 psi, the
automated pre-dive check will pass and the pre-dive test routine will continue. There is no
upper limit for cylinder pressures for these two tests. However, it should be noted that the
high-pressure sensors themselves have an upper limit to the pressure they can correctly read.
The high-pressure sensor for the oxygen cylinder is limited to 207 bar / 3097 psi, and the
sensor for the diluent is limited to 300 bar / 4410 psi. Exposing either sensor to a pressure in
excess of these limits may yield unpredictable results. Also, oxygen pressures in excess of
about 135 bar / 2000 psi pose a substantially increased risk of fire.
