User manual

Poseidon MKVI User Manual
Chapter 1 Page 3
Breathing loop overview
The most visible elements of the front portion of the Poseidon MKVI comprise
the breathing loop: breathing hoses; convertible open and closed-circuit
mouthpiece with built-in automatic diluent addition valve (ADV); water diver-
sion manifolds (sometimes referred to as “T-ports” or “Shoulder Ports”); and
the left (inhalation) and right (exhalation) counterlungs.
The breathing loop is a compliant system (its volume changes in response to
breathing). Its purpose is to provide an external reservoir for the exhaled
breathing gas and to direct the ow to the gas processing unit in the backpack.
One-way checkvalves in the mouthpiece direct the exhaled gas such that it
moves from the mouthpiece to the right front (exhalation) breathing hose, into
the right water diversion manifold and into the right counterlung.
During normal use, water will sometimes collect in both of the front breathing
hoses, but predominantly it will collect in the right front (exhalation) breathing
hose. The right-side water diversion manifold directs the water into the right
counterlung, while the breathing gas continues through the loop towards the
CO
2
absorbent cartridge. At the bottom of the right counterlung is a variable-
tension dump valve that can be used to vent the water periodically during the
course of a dive.
The counterlungs (left and right) are each sized to be about half the volume of
a full breath for an average individual. This design – known as a “dual over-
the-shoulder” counterlungs – optimizes the ease of breathing underwater.
Those familiar with open-circuit diving will notice an immediate improvement
in diving comfort when using the Poseidon MKVI because of this design.
Diluent cylinder valve
Diluent regulator
Electronics module
Oxygen regulator
Oxygen cylinder valve
Diluent high
pressure sensor
Left rear breathing
hose connection
Diluent cylinder
Cylinder connection
bands
Tank connection
bracket
Gas injection block
Carbon dioxide (CO
2
) removal
cartridge housing
Smart battery
Oxygen cylinder
Right rear
breathing hose
connection
Oxygen high
pressure sensor
Figure 1-4. Back view of Poseidon MKVI.