POSEIDON MKVI User manual

Poseidon MKVI User Manual Chapter 1
Page 1
POSEIDON MKVI USER MANUAL

Poseidon MKVI User Manual Chapter 1
Page i
Table of Contents
Table of Contents...................................................................................................i
Conventions Used in this Guide............................................................................ iv
Preface .................................................................................................................v
Conformance With CE Requirements.................................................................... vi
Chapter 1 - Preparation & Assembly
Part 1 – Preparation
An Overview of the Poseidon MKVI........................................................................1
Primary Display ................................................................................................... 1
Open-Circuit / Closed-Circuit Mouthpiece.......................................................2
Automatic diluent addition valve (ADV)............................................................2
Heads-up display (HUD).................................................................................2
Breathing loop overview .................................................................................3
Carbon dioxide absorbent cartridge ..............................................................4
Gas injection module......................................................................................4
Electronics module.........................................................................................4
Smart battery.................................................................................................4
Smart battery care ................................................................................................5
Safety............................................................................................................5
Charging........................................................................................................6
Long-term storage .........................................................................................7
Decompression data ......................................................................................7
Dive log data..................................................................................................8
O-ring care and maintenance ................................................................................8
Cylinders and regulators......................................................................................10
Filling the cylinders.......................................................................................11
Part 2 – Assembly
1. Stabjacket / BCD / Wing. ................................................................................13
2. Tank band.......................................................................................................14
3. Counter lungs to BCD / Harness. ....................................................................15
4. Rear CC hoses to counter lung. ......................................................................16
5. Rear CC loop hoses. .......................................................................................18
6. Attaching the cylinders. ...................................................................................20
7. E-module. .......................................................................................................21
8. 1st stages.......................................................................................................23
9. LP hose & HUD to mouthpiece. .......................................................................25
10. Jetstream Octopus........................................................................................26
11. Front CC hoses to counter lung T-section. .....................................................27
12. Front CC hoses to mouthpiece. .....................................................................28
13. Scrubber. ......................................................................................................30
Servicing.............................................................................................................36
Chapter 2 - Pre-dive procedures
Initial Pre-dive procedures
Gas supply cylinders ....................................................................................37
CO2Absorbent Cartridge .............................................................................37
Intact Breathing Loop Verication .................................................................38

Poseidon MKVI User Manual Chapter 1
Page ii
Negative-Pressure Loop Test........................................................................38
Electronics Power-Up...................................................................................39
Power-up self test (test 1 - 38) .....................................................................40
Pre-Dive Tests (test 39 - 55) .........................................................................41
Closed Circuit mouthpiece position (test 39) .................................................41
Tissue tension test (test 40)..........................................................................42
Open circuit mouthpiece position (test 43) ....................................................42
Oxygen and diluent cylinder supplies /test 44 & 45) ......................................42
Battery power verication (test 48)................................................................43
Positive pressure loop test (test 49) ..............................................................43
Closed circuit mouthpiece position (test 50)..................................................44
Oxygen sensor calibration (test 53)...............................................................45
Open circuit regulator function (test 54) ........................................................45
Service interval check (test 55) .....................................................................46
Cleared to dive.............................................................................................46
Pre-dive checklist ........................................................................................47
Chapter 3 - Dive procedures
Monitoring alarms ...............................................................................................48
HUD vibrator................................................................................................48
HUD Light....................................................................................................49
Audio alarm .................................................................................................49
Buddy alert light...........................................................................................49
Monitoring the primary display ............................................................................49
Units of measure..........................................................................................51
Alarm signal area .........................................................................................51
Abort! and open circuit alerts........................................................................51
DO NOT DIVE alert.......................................................................................51
General alert ................................................................................................52
Electronics alert ...........................................................................................52
Decompression ceiling alert..........................................................................52
Stop alert.....................................................................................................52
PO2value.....................................................................................................52
PO2setpoint ................................................................................................53
Hyperoxic linearity test .................................................................................53
Oxygen sensor condence ...........................................................................54
Mouthpiece position.....................................................................................54
Current depth ..............................................................................................55
Maximum depth / Ceiling .............................................................................55
Remaining dive time (RDT) ...........................................................................56
Elapsed dive time.........................................................................................56
Ascend/descend arrow ................................................................................56
Battery life indicator .....................................................................................57
Temperature ................................................................................................57
Cylinder pressure indicators .........................................................................57
Ascent rate indicator ....................................................................................57
System monitoring ..............................................................................................58
Monitoring the PO2value..............................................................................58
Monitoring gas supplies ...............................................................................58
Monitoring remaining dive time .....................................................................58
Breathing underwater..........................................................................................59
Counterlung placement ................................................................................59
Counterlung strap adjustments.....................................................................59
Tips on breathing .........................................................................................59
Tips on buoyancy control .............................................................................60
Venting water from the loop..........................................................................60
Managing ascents...............................................................................................61
Ending the dive ...................................................................................................61
Safe diving with the Poseidon MKVI.....................................................................62
Chapter 4 - Post-dive care and maintenance
After each dive....................................................................................................63
Power down ................................................................................................63

Poseidon MKVI User Manual Chapter 1
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Replacing the oxygen and CO2absorbent cartridge ......................................63
Removing the electronics module ................................................................63
Replacing the water trap sponges ................................................................64
After each day of diving.......................................................................................64
Open the breathing loop...............................................................................64
Store the electronics ....................................................................................64
Long term storage and care ................................................................................64
Storage .......................................................................................................64
Replacing oxygen sensors............................................................................65
Traveling with the Poseidon MKVI ........................................................................67
Preparing the cylinders.................................................................................67
Appendix 1 - Troubleshooting guide
Automatic pre-dive test .......................................................................................68
Standard response to test failure ..................................................................69
Troubleshooting table...................................................................................69
Hardware issues .................................................................................................69
If you get an error on test 49 ........................................................................70
Error on test 53............................................................................................70
Depth reading difference ..............................................................................70
C1 alarms on land........................................................................................70
Hyperoxic linearity test .................................................................................71
How the PO2alarm works ............................................................................71
What to do if I can’t resolve the problem ......................................................71
Table of the automatic pre-dive tests ...................................................................72
Appendix 2 - Deco 40 / Deco Trimix 48m/60 m
Introduction ........................................................................................................81
Assembly Technical 60 m Counter lungs to BCD/Harness/Regulators ..................82
Rear CC hoses to counter lung ....................................................................83
Manual additions..........................................................................................83
Routing the inator hoses.............................................................................84
Setting up decompression congured MKVI.........................................................85
Decompression permitted ............................................................................85
Decompression enabled...............................................................................85
40m Deco Version........................................................................................85
48m/60m Deco / Trimix Version....................................................................85
Maximum TTS..............................................................................................85
Pre-Dive Procedures with a MKVI enabled for Decompression Diving ...................86
48m/60m Deco Trimix..................................................................................86
Switching in between batteries ............................................................................86
Procedure....................................................................................................86
Decompression Diving with the MKVI...................................................................87
Controlling Resource Algorithm (CRA)..........................................................87
Open-Circuit Bailout.....................................................................................87
Set point......................................................................................................87

Poseidon MKVI User Manual Chapter 1
Page iv
Text, photographs and gures copyright © 2008-2013
by Poseidon Diving Systems AB
ALL RIGHTS RESERVED
Manual Version 2.6 - September 2013
No part of this book may be reproduced or transmitted in any form or by any
means, electronic or mechanical, including photocopying, recording or by
any information storage retrieval system, without permission in writing from
an authorized representative of Poseidon Diving Systems AB.
On certain pictures in this manual the MKVI rebreather may be equipped with
accessories which are not part of the standard scope of delivery.
DANGER:
The Poseidon MKVI is a fully closed-circuit diving apparatus,
which functions in a manner distinctly different from traditional
open-circuit scuba. Do not attempt to use the Poseidon MKVI
without proper professional instruction from an authorized
Poseidon MKVI Instructor, or without a thorough and complete
working knowledge of the material contained in this manual.
Careless use of the Poseidon MKVI can lead to hypoxic blackout
in any environment without any prior warning symptoms. Careless
use of the Poseidon MKVI at depths underwater greater than 6
msw (meters of seawater) [20 fsw (feet of seawater)] can lead to
seizure without any prior warning symptoms. Both conditions can
cause serious injury or death. The Poseidon MKVI is equipped
with sophisticated electronic control systems, which will allow
a properly trained user to avoid these situations. It is the user’s
responsibility to attentively monitor these systems when using the
Poseidon MKVI and to have a working knowledge of the abort
procedures should a problem arise.
Conventions used in this guide
This User’s Guide is NOT intended for use as a training manual, or in any way as a
substitute for proper training through a legitimate training agency approved by
Poseidon AB. It is only intended to provide basic information concerning the Poseidon
MKVI.
Throughout this Guide, special alert boxes have been inserted to draw attention to
critical information. Three levels of alerts are used in conjunction with color-coded
triangle symbols, as follows:
DANGER:
Alert boxes that are RED contain extremely critical information
related to the safety and well-being of the diver. Failure to comply
with information contained in these boxes could lead to serious
injury or death.
IMPORTANT:
Alert boxes that are BLUE contain important information about the
proper care and maintenance of the Poseidon MKVI, and that may
increase diver comfort or enhance enjoyment during dives.
WARNING:
Alert boxes that are YELLOW contain vital information that may
impact a diver’s safety and/or proper function of the Poseidon
MKVI. Though generally not life-threatening, information contained
in these boxes should not be ignored.

Poseidon MKVI User Manual Chapter 1
Page v
Preface
Congratulations on your decision to purchase the Poseidon MKVI Closed-Circuit
Rebreather (CCR). The Poseidon MKVI design includes several fundamental improve-
ments over previous closed-circuit rebreather designs. Among the breakthroughs are:
• Extreme compactness – at only 18 kg / 40 lbs ”ready to dive” and 9 kg / 20 lbs
“travel weight” the MKVI is one of the world’s smallest rebreathers. Take it as
carry-on baggage when ying. Enjoy the freedom. Yet it is not “lightweight” in terms
of performance – you get three depth-independent hours1 of near-silent diving.
• The rst truly auto-calibrating and auto-validating rebreather. The MKVI uses a
patented automated method to verify that the oxygen sensors are working
properly at all times – both before and during a dive.
• An intelligent battery – it’s your personal power and data storage system. Plug it
in and the system knows it’s you, as well as your dive history, including repetitive
dive information. Remove the modular battery, put it in your shirt pocket, and take
it home to recharge it. When you are ready to dive, take the battery from the
charger and plug it into the rebreather.
• True plug-and-play carbon dioxide absorbent cartridges. Simple and fast to use.
Pre-packed axial cartridges of SofnoDive®797 absorbent give you 3 hours
minimum diving range1and can be changed-out and replaced in seconds.
• The world’s most advanced rebreather interface – The MKVI contains ve separate
warning and advisory systems so that you get the information you need to manage
your dive without the task-loading normally associated with rebreathers. The main
Poseidon MKVI data interface is a large format at screen panel that displays all
you need to know about consumables management – cylinder pressures, dive
time, depth, oxygen level, and it incorporates a sophisticated resource algorithm
that monitors all systems for you and tells you when its time to head up. If things
are not going correctly for whatever reason, the MKVI has audible, tactile, and
visual warning systems to get your attention, and to advise your diving partner of
your status.
1 Unlike open-circuit scuba, the rate of gas consumption on the Poseidon MKVI does not
depend on the depth of the dive. Instead, the oxygen supply depends on how fast the diver
consumes oxygen through metabolism. Divers with large muscle mass, and/or working
hard underwater, will consume oxygen faster, leading to shorter total dive times. Conversely,
smaller divers with less muscle mass, or relaxed divers who are not working hard, will gain
signicant improvements in dive duration..
• Switchable mouthpiece – in a signicant new patented design, the Poseidon
MKVI gives you the ability to switch from closed-circuit to open-circuit operation
in one easy motion, without the need to search for a spare mouthpiece in an
emergency. The ultra-compact switchable mouthpiece is lightweight and easy to
breathe, giving you high performance in both open-circuit and closed-circuit
modes. The MKVI mouthpiece also combines in the same housing a pressure
balanced “Automatic Diluent Addition Valve” (ADV) that compensates for breathing
volume in closed-circuit mode, so that you will never run short of a full breath
during a dive.
• Easy maintenance – the entire rebreather breaks down rapidly for washing,
drying, and storage. No tools needed.
• New software releases can be downloaded and installed over the internet, and
various system parameters can be customized to meet your particular dive
operating paradigm.

Poseidon MKVI User Manual Chapter 1
Page vi
Conformance with CE requirements
The information listed in this chapter are the CE requirements that have to be met to
get a CE approval and they are NOT the exact specications of the Poseidon MKVI.
The exact specications and values of the MKVI can be found in the later chapters of this
user guide. The below text shows that the MKVI operates within these CE require-
ments.
In conformance with the European Standard EN 14143, section 8, the following
information is provided herein:
8.1
This manual contains information that will enable trained and qualied persons to
assemble and use the Poseidon MKVI in a safe manner.
8.2
This manual is written in the English language.
8.3
The application of the Poseidon MKVI is as a diving apparatus, to be used for
recreational, no-decompression diving with mixtures of air and oxygen.
The Poseidon MKVI is certied to a maximum operating depth of 60 meters (197 feet).
Two gas supply mixtures are used with the MKVI: air and oxygen (>92% pure); and
the maximum depth for the resultant breathing mixture blended by the Poseidon
MKVI is 60 meters (197 feet).
Use of the MKVI is limited to diving underwater, solely by persons who have received
proper training.
Detailed instructions on assembly of the Poseidon MKVI, including descriptions of
the individual components, the specic connections between components, and the
various safety devices, are included within Chapters 1 and 2 of this manual.
The user shall be able to understand the risk and make an assesment regarding the
risk of using the Poseidon MKVI, with input from the manual before a dive if the diver
believes it is needed.
The operating temperature for the Poseidon MKVI is between a minimum of 4º Celsius
(39º Farenheit), and a maximum of 35º Celsius (95º Farenheit). Operation at temperatures
outside of this range may lead to unreliable function.
The Poseidon MKVI is intended for use on dives involving low to moderate work
rates, typical of normal recreational diving activities. Although it is capable of sustain-
ing divers operating with high work rates, this is not its intended purpose.
The Poseidon MKVI is intended to maintain a breathing gas mixture representing an
inspired oxygen partial pressure of between 0.5 bar (0.35 bar minimum) and 1.2 bar
(1.4 bar maximum). The oxygen fraction of the mixture depends upon depth and set
point. At the surface the oxygen fraction will vary from 50% to 100% and the nitrogen
fraction from 50% to 0%. At the maximum operating depth of 40 msw, the oxygen
fraction will vary from 20% (set point = 1.0) to 28% (set point = 1.4) and the nitrogen
fraction will vary from 80% (set point = 1.0) to 72% (set point 1.4). Users must monitor
displays and alarm systems and respond appropriately if oxygen concentrations
become unsafe.
The Poseidon MKVI requires the monitoring of a backlit liquid-crystal display (LCD)
screen, and thus should only be used when water visibility exceeds approximately
30 centimeters. Using the MKVI in visibility conditions that prohibit viewing of the LCD
screen poses increased risks of operation.
The Poseidon MKVI incorporates high-pressure oxygen as one of its supply gas
mixtures, and uses equipment that has been cleaned and prepared specically for
use with high-pressure oxygen. Appropriate care must be taken when handling such
mixtures, especially when lling cylinders and providing proper maintainance and
oxygen-compatible cleanliness for all components exposed to high-pressure oxygen.
Components exposed to high-pressure oxygen (e.g., the oxygen regulator and associated
pneumatic components) must be serviced by a qualied service center. Failure to
comply with these instructions could lead to an oxygen re and may cause serious
injury or death.
The Poseidon MKVI requires proper pre-dive setup, and several important verication
procedures that must be carried out by the diver. Details of these procedures are
included in Chapters 1 and 2 of this Manual. The MKVI also incorporates many auto-
matic system tests as part of the power-up procedure. Using the MKVI without com-
pleting these automatic system tests poses signicantly increased risk to the diver.

Poseidon MKVI User Manual Chapter 1
Page vii
Chapter 3 of this Manual describes procedures for donning and tting of the MKVI, to
ensure proper positioning on the diver, as well as instructions for proper use while
conducting a dive.
Chapter 4 of this Manual describes appropriate post-dive procedures and long-term
storage and maintenance requirements for the Poseidon MKVI, including conditions
for storage, shelf-life of certain components, and appropriate precautions; as well as
a maintenence and inspection schedule. Failure to comply with these procedures
may result in deteriorated and/or damaged components, and can lead to improper
functioning of the equipment. A separate set of instructions detailing maintenance
requirements is also provided for reference purposes.
Appendix 1 covers troubleshooting of the Poseidon MKVI.
Appendix 2 covers upgrade modules intended for technical diving with the Poseidon
MKVI.
8.4
The diluent cylinder for the Poseidon MKVI should only be lled with Grade-E (or
equivalent) air.
The oxygen cylinder should be lled with oxygen, containing less than 0.4%
impurities.
The Poseidon MKVI may only be used with specially-designed Sofnodive®797 pre-
packed cartridges manufactured by Molecular Products.
Only accessories and/or other personal protective equipment specically authorized
by Poseidon Diving Systems may be used with the Poseidon MKVI. All other third-
party additions or modications are not covered within the intended usage of this
equipment.
8.5
The Poseidon MKVI is designed to extend the duration of recreational dives.

Poseidon MKVI User Manual Chapter 1 Page 1
Chapter 1 – Preparation and Assembly
Part 1 – Preparation
This chapter describes the steps to assemble and prepare the Poseidon MKVI
for diving. The MKVI is a modular device with several key systems. Each of
these systems is described in a sequence that naturally follows the way one
would service the rig.
An overview of the Poseidon MKVI
Throughout this manual, the terms “left”, “right”, “front”, and “back” refer to
specic areas of the Poseidon MKVI. Figures 1-1 and 1-4 illustrate these loca-
tions and the main systems of the Poseidon MKVI. The “left” side of the rig
corresponds to a diver’s left side when wearing the rig normally; the “right”
side of the rig corresponds to the right side of the diver when wearing the rig
normally. The “front” of the MKVI is the location furthest in front of a diver’s
chest when wearing the rig normally; the “back” of the MKVI is the location
furthest behind the diver’s back when wearing the rig normally. Following is a
brief description of each of the major components.
Figure 1-1. Front view of assembled Poseidon MKVI.
Right rear
breathing hose
Right side water
diversion
manifold
Right side
(exhalation)
counterlung
Right front
breathing
hose
Counterlung
Over
Pressurization
Valve (OPV)
Head up display (HUD)
Closed circuit/open circuit
convertible mouthpiece incl.
Auto diluent addition valve (ADV)
Jetstream Octopus
Purge Button
Primary display
Left front
breathing hose
Left side
(inhalation)
counterlung
Left side water
diversion manifold
Left rear
breathing hose
Primary display
The Poseidon MKVI is equipped with a custom glass liquid crystal display
(LCD) with large, bright, crisp letters for easy reading at a glance underwater.
It is designed specically for recreational divers and presents only the informa-
tion needed for safe operation. It includes an automatic high efciency back-
light that illuminates the panel when ambient light levels are low. It also
includes an infrared data port, which allows communication with a PC for dive
log downloading, parameter setting, and software upgrades. Two wet-switch
contacts on the back of the display activate the MKVI electronics.

Poseidon MKVI User Manual Chapter 1 Page 2
Open circuit/closed circuit mouthpiece
One of the most amazing of several technology breakthroughs in the Poseidon MKVI is its
switch-able mouthpiece. It incorporates a high-performance lightweight open-circuit regulator,
and you can breathe it just that way, just like standard scuba. With a simple quarter-turn of an
easy-to-operate switch, the system is ready for fully closed-circuit, bubble-free, silent, depth-
independent diving.
Automatic diluent addition valve (ADV)
The mouthpiece also contains a patented system that integrates an automatic diluent addition
valve (ADV), which compensates for depth-related compression of the counterlung breathing
volume during descents. This ensures a full breath automatically, allowing for hands-free
descents. The Poseidon MKVI incorporates this into the mouthpiece with a special mechanism
that adjusts the trigger tension on the open-circuit second stage when diving in closed-circuit
mode, so that gas is only added when the counterlung volume is insufcient to provide a full
breath on inhalation.
Heads-up display (HUD)
The mouthpiece also includes a snap-in-place head-up display (HUD). The HUD contains its
own computer processor that communicates with other system processors via the network,
and includes both a high-intensity red LED to alert the diver of a potential problem (Figure 1-2),
and a patented Juergensen Marine vibration system that provides a tactile alarm system to
advise the diver to switch from closed-circuit to open-circuit mode, or vice versa. The HUD
also contains a sophisticated sensor to detect which position the mouthpiece is in (closed-
circuit or open-circuit).
Mouthpiece switch in closed circuit position
HUD
Purge button
Figure 1-3. Mouthpiece open- & closed circuit switch and Heads-up display (HUD)
Figure 1-2.
HUD with red LED on.

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
CO2absorbent 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 (CO2) removal
cartridge housing
Smart battery
Oxygen cylinder
Right rear
breathing hose
connection
Oxygen high
pressure sensor
Figure 1-4. Back view of Poseidon MKVI.

Poseidon MKVI User Manual Chapter 1
Page 4
Carbon dioxide absorbent cartridge
At the heart of all rebreathers is the requirement to remove the metabolically-generated
carbon dioxide (CO2) from the breathing loop and replace the oxygen consumed through
metabolism. The Poseidon MKVI is designed around a modular plug-and-play carbon dioxide
lter system. It is equipped to handle Molecular Products SofnoDive®797 axial ow pre-
packed cartridges. Procedures for changing out the cartridge are presented in detail below
in the Cartridge Housing discussion.
Gas injection module
In a fully-closed rebreather like the Poseidon MKVI, 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 MKVI is designed to
maintain the partial pressure of oxygen (PO2) 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 PO2“setpoint”. The gas injection module in the Poseidon MKVI
does this and much more. In a patented design, this module provides the mechanisms for
not only adding pure oxygen to make up for metabolized gas, but also to automatically cali-
brate the oxygen sensors prior to diving, as well as validate the sensors during the course of
each dive.
Electronics module
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 MKVI.
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, and stores not only your dive log
data, but also your decompression status (tissue tensions), keeping track of repetitive dive
status. 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 Figure 1-5. E-module with battery inserted.
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.

Poseidon MKVI User Manual Chapter 1
Page 5
Figure 1-6.
Smart battery module
Smart battery care
Figures 1-7 shows the installation procedure for the smart battery. The battery contains four
female quick-connect contact pins mounted on an extended cylindrical, o-ring-sealed post
that projects from the end of the battery. This mates to a receptacle with four corresponding
male xed pins in the electronics module inside a sealing cavity for the radial o-ring seal. Be
careful not to short the contact pins when the battery is not in the rig, and inspect the battery
socket receptacle on the electronics module prior to inserting battery to ensure there is no
water. Once the battery is properly installed in its docking slots and pushed all the way forward,
an audible “CLICK”will be heard as the safety latch closes. The battery is now ready for
diving.
To remove the battery from the electronics module, press the safety latch and rmly push the
top part of the battery outward, as shown in Figure 1-8. It is usually best to remove the battery
when the system is dry, to avoid water ingress to the electrical contacts.
Safety
The smart battery uses a high energy density lithium-ion rechargeable battery, similar to bat-
teries used in laptop computers. If any liquid or discoloration is observed inside the clear
plastic battery housing, dispose of the battery immediately. Disposal of an old or failed smart
battery should be in accordance with local laws regarding disposal of Li-ion laptop computer
batteries.
Figure 1-7. (Left) Align the retainer screw posts on the Smart Battery with the receiver slots
at the top of the Electronics module (note that the 4 contact pins in the housing must align
with those on the battery); (Right): push the battery into the slot, engaging the pins and the
radial o-ring seal, until an audible “snap” is heard as the safety latch closes.
Figure 1-8. Removing the smart battery
Receiver
slot
Retainer
screw post
Safety latch

Poseidon MKVI User Manual Chapter 1
Page 6
Charging
Included with the Poseidon MKVI is a proprietary multi-function desk-top charger unit that
includes adapters for most international power outlets. The battery charger has three status
lights arranged in a circular pattern on the open section of the base. These are, in counter-
clockwise order from the lower left in Figure 1-9: power, “Learn Cycle” status, and charge
status.
Power Indicator Light: When green, the power is “on” and the charger is ready to operate. If
it occasionally “blips”, the charger does not have external power, and is actually draining the
battery.
Learn Cycle Indicator Light: The middle light indicates the status of a “Learn Cycle”. The
battery has its own onboard computer that monitors the state of charge. Over a period of
weeks to months, the computer’s estimate of the remaining power in the battery gradually
decreases in accuracy. The computer can “re-learn” what a full (100%) charged battery should
look like using the Learn Cycle of the charger. The battery computer keeps track of how long
it has been since the last time it has undergone a full Learn Cycle. If that time exceeds a certain
value, the computer will advise the user to perform an optional Learn Cycle. If the time since
the last Learn Cycle is very long, the computer may automatically initiate a Learn Cycle. The
Learn Cycle takes approximately 8 hours to complete. Once a Learn Cycle has been initiated,
it can only be stopped either by successful completion of the Learn Cycle or by physically
removing the battery from the charger (not recommended).
Power status on/off
Learn cycle status
Charge status
Learn cycle activation button
Figure 1-9. (Left): Inserting the smart battery into the desktop charging station. The battery
screw posts align with the vertical slots; the battery is pushed down until the contact post
mates with the offset cylindrical receiver hole. (Right): The battery properly inserted into the
charger. See the text for denitions of the status indicator lights.
WARNING:
Removing the battery from the charger in the middle of a Learn
Cycle will leave an uncertain state of charge on the battery,
increasing the risk of a power failure during a dive.
The Learn Cycle indicator light has the following meanings when plugged in with the smart
battery inserted:
• Off: Learn Cycle not needed or not in progress.
• Alternating Red and Green ashing once per second: Learn Cycle is recommended.
• Both Red and Green simultaneously ashing once per second: Learn Cycle is in progress.
• Red continuously on: Learn Cycle has failed (often caused by power loss or user
intervention).
• Green continuously on: Learn Cycle successfully completed.

Poseidon MKVI User Manual Chapter 1
Page 7
The Learn Cycle Activation Button: Just above the Learn Cycle indicator light is a button.
Pressing the button will manually initiate a Learn Cycle. It may be pushed at any time during a
regular charge cycle to initiate a Learn Cycle.
The System will require a Learn Cycle if the smart battery is fully depleted; if it has been more
than 90 days since the last Learn Cycle; or if the cell has had more than 20 charge cycles since
the last Learn Cycle. The system will recommend a Learn Cycle if it has been more than 45
days since the last Learn Cycle or if the cell has had 10 or more charge cycles since the last
Learn Cycle.
Charge Cycle Indicator Light: The right-most light on the charger is the charge cycle indicator,
and it has the following meanings when plugged in with the smart battery inserted:
• Off: The battery is being discharged as part of a Learn Cycle.
• Alternating Red and Green ashing once per second: No battery detected.
• Both Red and Green ashing: Battery is being charged (more green as battery is charged).
• Red continuously on: Charging has failed (may require a Learn Cycle).
• Green continuously on: Charge cycle completed successfully, battery is fully charged.
While charging, the light will ash rapidly when the battery is discharged, and will ash more
slowly as the battery becomes more charged. As a general rule of thumb, 1 minute on the
battery charger in standard charge cycle mode will load 10 minutes of charge into the battery.
Thus, if you charge while taking a 30 minute break between dives, you will have added 5 hours
of dive time to the battery.
Leaving the Smart Battery in the Charger: Although it is acceptable to leave the smart
battery in the charger when not in use, it is recommended that the battery be left attached to
the Poseidon MKVI after a successful charge for the following reasons:
• If power to the charger fails at any time, then having the battery in the charger will actually
deplete the cell – approximately as fast as if the battery was installed in the rig and the rig
powered up.
• Storing the battery in the Poseidon MKVI enables the depth sensor and the wet switch on
the back of the primary display. If someone wearing the MKVI accidentally falls into the
water, the system will automatically power up the rig, enhancing the probability for survival
of the user. This is only possible if the battery is charged and stored in the rig.
• Storing the battery in the Poseidon MKVI reduces the probability of debris entry and impact
damage to the battery contacts in the electronic module.
Long-term storage
Allowing the smart battery to sit for long periods of time on-shelf without recharge will lead to
premature failure of the battery. The best storage method, if the battery will not be used for a
substantial period of time, would be to top off the charge once a month by running it on the
normal charge cycle in the desktop charger. If this is not possible, then the best long term
solution is to leave the battery on the charger (with the power to the charger turned on). The
method of monthly top-off of charge, however, will maximize the battery life. Store the battery
in a cool, dry environment.
Decompression data
In the Poseidon MKVI rebreather, individual user decompression data are stored in both the
backpack computer and the smart battery computer. Thus, every user carries their decom-
pression information with them when they remove the battery. If the same user dives the same
rig, then the diver will receive repetitive dive surface credit for the time spent on the surface
(even if the battery is removed from the rig between dives). The decompression algorithm is a
9-compartment real-time implementation of the industry-proven DCAP decompression engine.
It is strongly recommended that you use the same battery in the same Poseidon MKVI for any
repetitive series of dives. Once sufcient surface credit has cleared the decompression model
entirely (generally 24 hours of no diving) then you can swap batteries between rebreathers
without risk.
WARNING:
Misuse of this feature is NOT recommended.

Poseidon MKVI User Manual Chapter 1
Page 8
IMPORTANT:
If a user removes the battery from the rig they were diving and
then uses that battery in a different Poseidon MKVI unit for
subsequent dives, the decompression data in the rebreather
system will differ from those contained in the battery. To ensure
that a safe decompression situation will always exist, the
backpack computer will take the most conservative tissue-
tension data for each of the nine separate compartments of
the decompression engine from the two sets of values, and use
those to construct a new, worst-case tissue model to be used
on all subsequent dives. This will result in a decompression
penalty (and therefore reduced repetitive no-decompression dive
times) for the user who may have had a lower decompression
exposure before swapping batteries. Conversely, a user with a
known higher decompression debt transferring their battery to a
Poseidon MKVI with a known lower decompression debt will see
little difference in how the rig tracks decompression (except see
Warning message below).
DANGER:
If a user swaps batteries with another Poseidon MKVI unit than the
one they were diving, and if they incurred a decompression debt,
and if the battery computer memory storing the decompression
information is corrupted (e.g. from inadvertant electrostatic
discharge) there is a possibility that the computer system may
only recognize the rebreather system’s stored decompression
data. In that event, and if the previous diver of that rebreather
did not incur as serious a decompression debt, then swapping
batteries could lead to serious injury or death from incorrect
decompression on subsequent dives.
WARNING:
If a user changes batteries with a Poseidon MKVI unit other
than the one they were most recently diving and then turns
on the power of the new Poseidon MKVI with their original
battery installed, the Pre-Dive test routine will FAIL Test 40
(decompression comparison between battery and backpack
computers). This is a warning that there is a difference in the
decompression data stored in the rebreather’s computer and
the battery just inserted. The system will now prompt you for
conrmation while simultaneously scrolling dECO rESEt through
the PO2 eld. The user assumes all responsibility for their own
decompression safety in this event. The rebreather will calculate
decompression based on the most conservative values from
each set of decompression data.
Dive log data
The Poseidon MKVI automatically creates an extensive dive log every time the system is pow-
ered-up. The information stored in this log will be of signicant interest in reconstructing dives
and learning about how the rig and you behave during a dive. A Windows-based MKVI dive log
reviewer are available as a download from Poseidon (www.poseidon.com). In general, the unit
will store approximately 20 hours of dive time; more if the dives were of a simple nature with
uncomplicated proles. Examples of the common types of data you can review are battery
information, dive time and depth. However, the dive log contains much, much more information.
http://www.poseidon.com/support/discovery
O-ring care and maintenance
The Poseidon MKVI is a computer-controlled precision underwater instrument. Its successful
continued operation depends upon preventing water from entering the breathing loop, gas
processor, and electronics systems. To do this, and to keep the rig modular and easy to use
and maintain, there are dozens of o-ring seals. These fall into two design classes: “axial” o-ring
seals and “radial” o-ring seals. Figure 1-10 shows a typical use of a axial o-ring seal, as used

Poseidon MKVI User Manual Chapter 1
Page 9
in the CO2absorbent cartridge lid. Axial o-rings are laid into an annular groove in the body of
the object to be sealed.
The object is then pressed perpendicularly agains a at, clean sealing surface. The axial o-ring
is then compressed along its top side by the at mating surface and compressed into the
groove. This compression of the o-ring causes it to seal against the sides of the groove and to
the at mating surface. Because a release of the mating pressure would result in a leak in a
face type seal, these require a securing mechanism that not only prevents the part from lifting
off accidentally, but also actively compresses the axial o-ring against the at mating surface. In
the case of the CO2cartridge, the cartridge end plate is equipped with four thumb screws to
secure it in place and tighten it down.
A second, and more commonly used seal is the “ radial “ o-ring. Figure 1-11 shows a typical
implementation in the Poseidon MKVI breathing hose and hose connection ports. In contrast
to a axial o-ring seal, a radial seal involves a circular groove that goes around a cylindrical or
semi-cylindrical object (it can be a rectangular object with rounded corners provided the
corners have a sufciently large radius – an example of this is the Electronics Module dual
radial seals). In a radial seal, the groove is designed such that the o-ring snaps into the groove
with a certain pre-tension. Once seated the o-ring cannot leave the groove. To complete the
seal, the side of the connection containing the radial o-ring and groove is inserted into a cylin-
drical receiving surface. As the o-ring is inserted, the cylindrical surface uniformly compresses
the radial o-ring and creates the seal against all contacting surfaces. The important distinction
is that with a radial seal it is possible to rotate the objects relative to one another and still retain
a good waterproof seal. This is the reason the breathing hoses use radial seals, for example
– so that you can adjust their positions and that of the mouthpiece without having to make and
break the connections.
Radial o-ring seals still require a retainer to prevent them from accidental disassembly during
diving. For hose connections we use rotating shells whose threads engage a capture thread
on the mating part (see Figure 1-11 for example).
For face and radial o-rings to properly work, the diver is responsible for ensuring the
following:
• The o-ring is clean and free of debris and scratches (no cuts, gouges, dust, dirt, sand, hair, etc.)
• The o-ring is lubricated with an approved o-ring grease.
• The sealing surfaces are clean and free of debris, scratches and gouges.
• The sealing surfaces are lubricated with an approved o-ring grease.
• The retainer mechanism (e.g. hand screws, hand nuts, or threaded shells) is securely
in place.
”Radial” o-ring seal
Sealing surface for ”radial” o-ring seal
Retainer nut capture thread
Figure 1-10.
Typical “ Face “ type o-ring seal.
Figure 1-11. Typical “ Radial “ type o-ring seal.
“ Face “ o-ring seal

Poseidon MKVI User Manual Chapter 1
Page 10
Figure 1-12. How the rig should appear when properly assembled.
Diluent cylinder
Cylinders and regulators
The Poseidon MKVI (EU version only) is factory-issued with two 3-liter aluminum cylinders with
Poseidon post-style valves (see Figure 1-12). The oxygen cylinder has a white valve knob and
the diluent cylinder has a black valve knob. Both cylinders are pressure-rated to 204 bar /
3000 psi service pressure. However, the specied maximum safe FILL pressure for the oxygen
cylinder is 135 bar / 2000 psi. The reason is twofold: rst, the risk of oxygen re increases
sharply at higher pressures; and second, using a greater supply of oxygen increases the risk
that the CO2absorbent cartridge may not be sufcient to last for the entire dive on a single ll.
It is also extremely important to NOT replace either of regulators that are provided with the
Poseidon MKVI. The oxygen cylinder, valve, and regulator have been cleaned for oxygen
service at the rated cylinder pressure; using regulators or valves not so cleaned dramatically
increases the risk of oxygen re and/or explosion. More importantly, the provided regulators
have been adjusted with a lower interstage pressure for use with the oxygen and diluent
solenoid valves. Using different regulators with higher interstage pressures will cause the
solenoid valves to fail, and may lead to permanent damage.
DANGER:
Do not ll the oxygen cylinder to more than 135 bar (2000 psi).
Doing so may allow a diver to exceed the duration of the absorbent
cartridge, which could lead to dangerously elevated CO2levels in
the breathing mixture.
DANGER:
Only use the rst-stage regulators provided with the Poseidon
MKVI. Not only do the provided regulators have specic features
required by this application (e.g. integrated over-pressure relief
valves, oxygen regulator cleaned for oxygen service), but the
interstage pressure of these regulators is adjusted for use with the
solenoid valves. Use of different rst-stage regulators can lead to
solenoid failure (thereby disabling gas control), and can also lead
to PERMANENT damage to the solenoid valves.
Oxygen cylinder

Poseidon MKVI User Manual Chapter 1
Page 11
Filling the cylinders
From a diving logistics perspective, the Poseidon MKVI differs from normal Scuba in that it
uses two separate gas supplies: a pure oxygen supply and a “diluent” supply. Pure oxygen is
necessary for the control system to exactly replace the oxygen consumed by metabolism. The
denition of a diluent gas in a rebreather is any gas that serves to dilute the oxygen when
mixed in the breathing loop. This diluting characteristic is a requirement of a closed-circuit
rebreather because oxygen is toxic at elevated partial pressures. If one were only using pure
oxygen in a rebreather the standard operating depth would be limited to 6 meters / 20 feet
underwater. Another characteristic of a suitable diluent gas is that it is normally selected so
that it is directly breathable as an open-circuit gas at the maximum operating depth of the
rebreather. General examples of diluent gases that can be used in rebreathers include: air,
nitrox, trimix, and heliox. The MKVI is in its recreational conguration limited to 40m / 130 feet
depth and uses only air as an allowed diluent, following established compressed air scuba
sport diving practices. The decompression algorithm requires that air be used as the diluent in
the Poseidon MKVI. For technical conguration and deeper setups (60m / 197 ft) refer to
Appendix 2.
Poseidon MKVI cylinders (both oxygen and diluent) should be lled by a qualied facility that is
properly trained and equipped to ll such cylinders.The requirements concerning maintenance
of oxygen clean systems, gas banks, and compressors are already handled by those centers
and all you need to do is present your cylinders for lling.
For those with less convenient access to such facilities, there are several practical consider-
ations. It may be worthwhile to acquire several spare Poseidon MKVI oxygen cylinders and
have those pre-lled for future dives when needed. If you will be visiting a dive resort or live
aboard boat, inquire ahead as to the availability of oxygen and/or the availability of pre-charged
cylinders on-site that are compatible with the MKVI. Note that the MKVI oxygen cylinders sold
in Europe contain a DIN M26x2 thread. This is larger than the G-5/8 DIN thread that is more
standard around the world. Poseidon sells oxygen cleaned converters that will allow lling of
the M26x2 oxygen cylinder from a standard G-5/8 male DIN tting.
DANGER:
Filling your own cylinders is dangerous business. You are
personally responsible for your well being and those around you
when you ll your own cylinders. Before you consider this option,
obtain formal training on the operation of the equipment and in
the maintenance of oxygen clean systems. Never overll any
Poseidon MKVI cylinder (oxygen or diluent). Service all equipment
per the manufacturer’s recommendations.
WARNING:
Do not attempt to use any diluent gas in the Poseidon MKVI other
than what has been congured via PC software tool. The use of
other diluents may lead to serious injury or death resulting from
decompression sickness.
IMPORTANT:
Air for compressed air line breathing shall have a dew point
sufcently low to prevent condensation and freezing.
Maximum water content of air at atmospheric pressure:
- 50 mg/m³ @ 40-200 bar / 580-2900psi Nominal pressure
- 35 mg/m³ > 200 bar / 2900 psi Nominal pressure
Corroded solenoids are not covered by warranty.

Poseidon MKVI User Manual Chapter 1
Page 12
Before you start assembling your Poseidon MKVI eCCR, you should perform the following
preparations:
• Make sure you have a scrubber that will last your planned dive(s).
• Fill your diluent tank with the correct gas.
• Fill your oxygen tank with the correct gas.
• Make sure your battery is fully charged and recently learn cycled.
• Make sure you have all parts and that they are without damage.
• Lubricate all o-rings that you can access.
Part 2 – Assembly
Please note that the Besea harness and the 11-inch adapter are both sold separately and
are not included in the Poseidon MKVI. The pre-packed scrubbers are consumables and
are sold separately and not included in the MKVI.
Standard tank band supplied with the MKVI, quick release buckles on the items sold
separately.