Poseidon SE7EN+ User Manual Chapter 1 Page 4
Carbon dioxide absorbent repackable cartridge
At the heart of all rebreathers is the requirement to remove the metabolically-generated
carbon dioxide (CO
2
) from the breathing loop and replace the oxygen consumed through
metabolism. The Poseidon SE7EN+ is designed around a modular plug-and-play carbon
dioxide lter system. It is equipped to handle Molecular Products SofnoDive
®
797.
Procedures for changing out the cartridge are presented in detail below in the Cartridge
Housing discussion.
Gas injection E-module
In a fully-closed rebreather like the Poseidon SE7EN+, oxygen is consumed by the diver and
a mechanism must be provided for replacement of that used oxygen. Otherwise the mixture
will slowly be depleted to dangerously oxygen low levels (hypoxia). The SE7EN+ is designed
to maintain the partial pressure of oxygen (PO
2
) well above hypoxic levels, and to also prevent
it from becoming too high (hyperoxia). This is achieved by a control system that uses sensors
that are responsive to the partial pressure of oxygen and a mechanism for the addition of
pure oxygen to the system when the sensors indicate that the oxygen level is below the
target value, known as the PO
2
“setpoint”. The gas injection E-module in the Poseidon
SE7EN+ does this and much more. In a patented design, this module provides the mecha-
nisms for not only adding pure oxygen to make up for metabolized gas, but also to automati-
cally calibrate the oxygen sensors prior to diving, as well as validate the sensors during the
course of each dive.
The electronics module provides a single plug-and-play component that includes the previ-
ously described gas injection module and the smart battery. It also includes the oxygen
sensors, the main computer system and the junction for the cables leading to the display,
cylinder pressure gages, and HUD. Two thumb-wheel screws allow for easy removal of the
electronics module from the gas processor housing after diving.
Smart battery
The smart battery (Figure 1-6) is another patent-pending design of the Poseidon SE7EN+.
It is a snap-in power supply that allows operation of the rebreather for up to 30 hours when
fully charged. It also contains its own onboard computer.The smart battery communicates
with the other system computers via the network, and contains two user feedback systems.
The rst system consists of two extremely bright red LEDs (one facing up, the other facing
backwards) that provide a wide viewing angle; the second is a 2-frequency acoustic speaker
that broadcasts a very audible tone through the water. Both systems are primarily designed
to convey the safety status of your diving rig to your partner from a distance. Once the rig is
properly turned off following a dive, the smart battery can be removed and taken to a
desk-top charging station. Use and maintenance of the smart battery are discussed later in
this chapter.
Figure 1-6. E-module with battery inserted.
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