Poseidon SE7EN+ User Manual Chapter 2 Page 38
Chapter 2 - Pre-dive procedures
The Poseidon SE7EN+ is a compact and very powerful life-support system that offers an
unprecedented new experience in recreational or technical diving diving. But it is also a
complex assembly of high technology that includes sensors, actuators, computers, and
software that need to operate reliably in an underwater environment, for the important purpose
of keeping a diver alive and healthy. For the same reasons that good pilots use pre-ight
checklists to ensure their ying machine has a high probability of successful take-off, ight,
and landing; so does the rebreather diver need to formalize the process leading up to a dive.
The SE7EN+ design team has gone to extraordinary measures to automate the pre-dive pro-
cedure and the operation of the rig during a dive. This chapter explains the pre-dive test pro-
cedures, including manual actions that are required by the user, and how to interpret the
results of the automated tests, should any of them fail to complete successfully.
Initial Pre-dive procedures
Gas supply cylinders
Before the dive, make sure there is enough diluent (air) and oxygen to carry out the dive you
plan to do. The EU version of the Poseidon SE7EN comes with a 3-liter/ 183-cubic inch
aluminum diluent (air) cylinder (with black valve knob) with a rated ll pressure of 204 bari, or a
3-liter steel diluent (air) cylinder (with black valve knob) with a rated ll pressure of 300 bar.
Filled to its maximum allowed working pressure, it holds 612 liter of air. Because this cylinder
DANGER:
Failure to properly and completely conduct the Pre-Dive tests
and to ensure that the rig is operating properly could lead to
permanent injury or death. Do NOT skip the Pre-Dive Procedure.
Your life depends on it.
is your open-circuit (OC) bailout gas in the event of an emergency, Poseidon strongly recom-
mends that this cylinder be full at the start of each dive. The included oxygen cylinder (white or
green valve knob) has the same capacity and pressure rating as the diluent cylinder, but the
recommended maximum lling pressure of oxygen is limited to 135 bar / 2000 psi for reasons of
re safety.
Attach both the diluent and oxygen cylinders using the procedures described in Chapter 1. Do
not turn the cylinders valves on initially, as this will result in wasted gas during certain portions
of the pre-dive tests. As described below, the cylinders should be turned on when the pre-dive
checks reach Test number 44 and 45. The pre-dive tests will fail if the pressure in the diluent
cylinder is less than 51 bar / 739psi, or the oxygen cylinder is less than 34 bar / 493 psi. Similarly,
if starting a dive with only a marginal amount of gas above these minimum safety limits, these
gas pressure limits will be reached soon after the start of the dive, leading to an unsatisfying
diving experience.
CO
2
Absorbent Cartridge
Follow the procedures described in Chapter 1 for installation a re-packable scrubber with Sofnolime
797 CO
2
absorbent cartridge. When conducting a repetitive dive, it’s critical to keep track of
the hours of personal use for the cartridge once it is installed. The absorbent cartridge must
be changed whenever the oxygen cylinder is re-lled. While many people experience a strong
reaction to CO
2
buildup (as would result from diving with a depleted or missing cartridge) in the
form of un-naturally rapid breathing rate, disorientation and the onset of a strong headache,
some people do not experience them. Change the cartridge every 2 hours and 10 minutes* of
use or whenever the oxygen cylinder is re-lled, whichever comes rst. See chapter 1, page
32 for information on how to repack and install the CO2 absorbent cartridge.
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