CLASSIC INSPIRATION INSTRUCTION MANUAL

Closed Circuit Rebreather, incorporating
User Instruction Manual
WARNING
Life support equipment, which includes the INSPIRATION Rebreather, requires
specialist training before use.
Several problems may arise when using a rebreather, many of which, if not dealt with properly, may
have fatal consequences. It is, therefore, essential that you understand exactly how this rebreather
works, the maintenance which must be carried out, the purpose of every component and the
operational requirements. This manual is not the definitive guide to rebreather diving and is no
substitute for proper training and closed circuit rebreather experience.
Do not use the rebreather without proper training.
Build up your experience gradually. Do not expect to be a good rebreather diver straight away. It
takes time and practise to perfect buoyancy control and to become aware of the idiosyncrasies of
rebreather diving and of the apparatus.
Most of the problems you can experience are referred to in this instruction manual. It is in
your interest that you take the time to read and study it.
All products are sold only on the understanding that only English Law applies in cases of warranty
claims and product liability, regardless of where the equipment is purchased or where used.
1997-2010
This manual remains the copyright of Ambient Pressure Diving Ltd and cannot be reproduced without prior written approval.
Author: Martin Parker
October 2010
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Version No. 02/10
-2-
CLOSED CIRCUIT
SURVIVAL
Rule No 1. Know your ppO2 at all times. -
This
cannot be over emphasised.
When you dive closed circuit you need to change the way you
think: Diving with conventional or open circuit equipment you need to know: “Will
I have something to breathe?”. But when diving with closed circuit equipment you
need to know: “What am I breathing?”. Never breathe from any rebreather without
knowing what you are breathing.
WARNING! If you fail to watch your ppO2 and understand the implications - you will die,
it is only a question of where and when.
The primary warning device for the ppO2 is the wrist display. The Head Up Displays are Secondary
warning devices.
The audible warning device is purely an additional safety aid and warns of excessive changes in ppO2
only.
All divers, not just those with a hearing impediment, must watch the displays and never rely on just
the audible warning.
If you are unable or unwilling to monitor your ppO2 displays regularly then you must not use a
rebreather.
Attitude keeps you alive: Normally, closed circuit rebreathers are used by
experienced open-circuit divers. This can bring a level of over-confidence which can
lead to serious problems. You are a novice again, please accept that and build your
rebreather experience gradually.
WARNING! There are no wet contacts for automatic activation when you enter the water.
YOU have to turn the electronics on and open the gas cylinder valves!
IF IN DOUBT, BAIL OUT
-3-
CONTENTS
INSPIRATION LAYOUT: ................................................................................................................... 8
VISION TEST
................................................................................................................................... 9
SECTION 1
IMPORTANT INFORMATION .............................................................................. 10
1.1
Gas ........................................................................................................................................ 10
1.2
Weighting ............................................................................................................................. 10
1.3
Buoyancy Control................................................................................................................. 11
1.4
Familiarity of Controls and Harness .................................................................................... 11
1.5
Understanding ppO2 ............................................................................................................. 11
1.6
Setpoint Selection ................................................................................................................. 12
1.7
Descending ........................................................................................................................... 13
1.8
Mask Clearing and Pressure Equalisation ............................................................................ 13
1.9
Mouthpiece ........................................................................................................................... 13
1.10 Ascending ............................................................................................................................. 13
1.11 Breathing Resistance ............................................................................................................ 14
1.12 Counterlung Choice .............................................................................................................. 14
1.13 Gas Consumption ................................................................................................................. 14
1.14 System Integrity - Leaks....................................................................................................... 15
1.15 Check for Water ................................................................................................................... 15
1.16 Flooding and Clearing Drills ................................................................................................ 16
1.17 Water Management .............................................................................................................. 16
1.18 System Integrity - Indications .............................................................................................. 17
1.19 Batteries ................................................................................................................................ 17
1.20 Surface Swimming ............................................................................................................... 17
1.21 Surface Buoyancy and Trim ................................................................................................. 17
1.22 Quick Post-Dive Checks ...................................................................................................... 17
1.23 Practise ................................................................................................................................. 18
1.24 Solenoid operation and the main oxygen risks during the dive ........................................... 19
SECTION 2
DEFINITIONS ......................................................................................................... 21
SECTION 3
OPERATIONAL CONSIDERATIONS .................................................................. 24
3.1
General ................................................................................................................................. 24
3.2
Gas Consumption ................................................................................................................. 25
3.3
Oxygen Benefits ................................................................................................................... 26
3.4
Decompression ..................................................................................................................... 27
3.5
Oxygen Controller ................................................................................................................ 27
3.5.1 Accuracy of the Oxygen Controller ..................................................................................... 27
3.5.2 Oxygen Cell Life .................................................................................................................. 28
3.5.3 Interpreting the ppO2 Displays ............................................................................................. 28
3.5.4 Effect of Moisture on the Cells ............................................................................................ 29
3.5.5 Setpoint Selection ................................................................................................................. 29
3.5.6 Pulmonary Oxygen Toxicity ................................................................................................ 30
3.5.7 Oxygen Limits for Diving Operations.................................................................................. 30
3.6
Duration of the CO2 Scrubber .............................................................................................. 31
3.6.1 How do I know when the CO2 absorbent can no longer absorb CO2? ................................. 32
3.6.2 Extra CO2 Considerations .................................................................................................... 32
3.7
Symptoms Associated with Low and High Oxygen Levels, High .........................................
CO2 Levels and Oxygen Toxicity ........................................................................................ 33
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SECTION 4
APPARATUS COMPONENTS .............................................................................. 34
4.1
Counterlungs ........................................................................................................................ 35
4.2
Over-Pressure Exhaust Valve .............................................................................................. 35
4.3
Mouthpiece Valve ................................................................................................................ 36
4.4
Breathing Hose Connectors ................................................................................................. 36
4.5
Colour Coding of Convoluted Hose Connections ............................................................... 37
4.6
Diluent and Oxygen Inflators............................................................................................... 37
4.7
Automatic Diluent Valve (ADV) ......................................................................................... 38
4.8
Weight Pocket ...................................................................................................................... 39
4.9
Buoyancy Compensator and Harness .................................................................................. 39
4.10 Auto Air ............................................................................................................................... 39
4.11 Audible Warning Device ..................................................................................................... 40
4.12 Oxygen Solenoid.................................................................................................................. 40
SECTION 5
POWER ON ............................................................................................................. 41
5.1
General ................................................................................................................................. 41
5.2
Switching On and Off .......................................................................................................... 41
5.3
Oxygen Cell Check .............................................................................................................. 42
5.4
Battery Check....................................................................................................................... 42
5.5
Elapsed On Time.................................................................................................................. 42
5.6
Check Diluent ...................................................................................................................... 43
5.7
The Slave Oxygen Controller .............................................................................................. 43
SECTION 6
CALIBRATION ...................................................................................................... 44
6.1
Must Calibrate! .................................................................................................................... 44
6.2
Calibrate? ............................................................................................................................. 44
6.3
Ambient Pressure ................................................................................................................ 45
6.4
Oxygen %............................................................................................................................. 45
6.5
Open Mouthpiece ................................................................................................................. 46
6.6
Open O2 Valve ..................................................................................................................... 46
6.7
Flushing Bag ........................................................................................................................ 46
6.8
No Oxygen - Check Valve ................................................................................................... 46
6.9
Cell Stuck ............................................................................................................................. 47
6.10 Out of Range ........................................................................................................................ 47
6.11 Flushing Bag ........................................................................................................................ 47
6.12 Master .................................................................................................................................. 47
6.13 Slave..................................................................................................................................... 48
6.14 Verification of ppO2 ............................................................................................................ 48
6.14.1 Indicators to look for during calibration .............................................................................. 48
6.14.2 Periodic Calibration Check .................................................................................................. 49
6.14.3 Linearity Check .................................................................................................................... 50
6.14.4 Checks prior to each use ...................................................................................................... 50
6.14.5 Verifying the ppO2 during the dive ..................................................................................... 50
SECTION 7
DIVE MODE ........................................................................................................... 52
7.1
High/Low ppO2 Setpoint Switch (Master Oxygen Controller only) ................................... 52
7.2
Slave Oxygen Controller...................................................................................................... 53
7.3
Backlight .............................................................................................................................. 53
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SECTION 8
MENU MODE ......................................................................................................... 54
SECTION 9
WARNINGS AND REMEDIES .............................................................................. 55
9.1
Low Oxygen Warning .......................................................................................................... 55
9.2
High Oxygen Warning ......................................................................................................... 55
9.3
“Cell warning”, early versions called this “Cell Error” ....................................................... 56
9.4
Two faulty cells occurring simultaneously, resulting in low oxygen or high oxygen risks . 56
9.5
Low Battery .......................................................................................................................... 57
9.6
Master Oxygen Controller - Power Failure .......................................................................... 57
9.7
Reset other unit ..................................................................................................................... 58
9.8
Error Assessment .................................................................................................................. 58
SECTION 10
MAINTENANCE ..................................................................................................... 59
10.1 CO2 Absorbent Replacement................................................................................................ 59
10.2 Gas Cylinders ....................................................................................................................... 65
10.3 First Stages ........................................................................................................................... 66
10.4 LP Oxygen Hose .................................................................................................................. 66
10.5 Post-Dive Maintenance ........................................................................................................ 67
10.5.1 Cleaning and Disinfecting the Unit ...................................................................................... 67
10.5.2 BUDDY Clean Disinfectant ................................................................................................. 67
10.5.3 Lubrication ........................................................................................................................... 67
10.5.4 Washing and Disinfecting the Breathing Circuit with BUDDY Clean ................................ 68
10.5.5 Oxygen Sensors .................................................................................................................... 69
10.5.6 Exchanging Oxygen Sensors ................................................................................................ 69
10.6 Storage .................................................................................................................................. 71
10.7 Precautions when using High Pressure Oxygen ................................................................... 72
10.8 Service Intervals ................................................................................................................... 72
SECTION 11
EMERGENCY PROCEDURES .............................................................................. 73
11.1 Bail-Out (Emergency Breathing) ......................................................................................... 73
11.2 Emergency Procedures ......................................................................................................... 73
11.3 Diluent Flush ........................................................................................................................ 74
11.4 Emergency Rescue of an Unconscious INSPIRATION Diver ............................................ 74
11.5 Flooded Loop ....................................................................................................................... 74
11.6 Manual Control of ppO2 ....................................................................................................... 75
11.6.1 Manual addition of O2 and O2 flush method ........................................................................ 75
11.6.2 Manual addition of diluent ................................................................................................... 75
11.6.3 Using the INSPIRATION as a pure oxygen rebreather ....................................................... 76
SECTION 12
BRIEFING OPEN CIRCUIT DIVE PARTNERS ................................................... 77
12.1 The Rebreather Diver – What to Expect, What to Do.......................................................... 77
12.2 Classic Problems, Causes and Resolutions .......................................................................... 78
SECTION 13
WARRANTY ........................................................................................................... 79
SECTION 14
IMPORTANT CAUTIONARY NOTES ................................................................. 80
SECTION 15
TECHNICAL DATA ............................................................................................... 81
Sofnolime Data ................................................................................................................................. 83
SECTION 16
DANGERS INTRODUCED BY USER MODIFICATIONS .................................. 84
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SECTION 17
DIVING DEATHS................................................................................................... 85
APPENDIX 1
POWER ON ............................................................................................................. 86
APPENDIX 2
DETERMINING THE OXYGEN PURITY (WHEN THE GAS QUALITY IS NOT
CERTIFIED) ............................................................................................................ 88
APPENDIX 3
SELF CHECK QUESTIONS AND ANSWERS..................................................... 90
APPENDIX 4
DECOMPRESSION TABLES ................................................................................ 92
APPENDIX 5
BUDDY CLEAN DATA SHEET ........................................................................... 93
APPENDIX 6
SOFNOLIME TRANSPORTATION DECLARATION ........................................ 95
APPENDIX 7
TRIMIX IN THE REBREATHER .......................................................................... 97
APPENDIX 8 EXPORT LICENSE REQUIREMENTS ................................................................. 98
APPENDIX 9 CHECK LISTS ....................................................................................................... 99
Pre Dive Check List ......................................................................................................................... 99
Pre-Breathe Sequence .................................................................................................................... 100
In-Water Checks and Important Procedures .................................................................................. 100
Post-dive actions ............................................................................................................................ 101
-7-
INSPIRATION LAYOUT:
Buzzer
Exhale T piece with
integral water-trap
Inhale T piece
Pull-dump exhaust
valve for Wing BC
Exhale counterlung
Dump/over pressure
relief valve (not shown)
Inhale counterlung
Weights to counter
hose buoyancy
Pull knob for manual dump
from counterlung
Wing Buoyancy
Compensator
Manual oxygen inflator
Manual diluent inflator
Open/Close Mouthpiece
Auto Air, BC inflator,
deflator, diluent 2nd stage,
diluent pressure relief valve
Diluent cylinder valve
readily accessible
Oxygen cylinder
pressure gauge
Pull knob for dumping gas
from BC when inverted
Diluent cylinder
pressure gauge
On switches
ppO2 displays, oxygen controllers
Manufactured in the UK by Ambient Pressure Diving Ltd , Unit 2C, Water-ma-Trout Industrial
Estate, Helston, Cornwall TR13 0LW. Telephone: 01326 563834. Fax: 01326 573605
EC Type approved by SGS United Kingdom Ltd, Unit 202b, Worle Parkway, Western-Super-Mare,
Somerset, BA22 6WA. Notified Body number 0120. Assisted by DERA (Defence Equipment
Research Agency, now QinetiQ), Alverstoke and ANSTI Test Systems, Hants.
The “Inspiration” are CE approved to 40m using an air diluent and 100m using a Heliox or Trimix
(with a max. END of 30m at 70m, reducing to an END of 24m at 100m). The EC Type Approval was
granted on the APD Manufacturer’s Technical Specification and satisfactory user trials. The
Technical Specification was based on the “Respiratory equipment-Self-contained re-breathing diving
apparatus” standard EN14143:2003 excluding clauses 5.6.1.3 (peak respiratory pressures at higher
breathing rates) and 5.8.8.(hose elongation test). It was considered that the products met the Basic
Health and Safety Requirements (Annex II) of the PPE Directive 89/686/EEC.
The ongoing certification to allow CE marking under Article 11B of the PPE Directive 89/686/EEC
is granted by Lloyd's Register Quality Assurance Ltd. CE0088.
Applicable law: All products are sold only on the understanding that only English Law applies in
any and all legal claims against the manufacturer, regardless of where the equipment is purchased or
where used. Should a claim be made the venue for this will be Truro, England. If this clause is not
acceptable to you or your family then return the product unused to your place of purchase for a
refund.
Warning: It is dangerous for untrained and uncertified persons to use the equipment covered
by this warranty. Therefore, use of this equipment by an untrained person renders any and all
warranties null and void.
-8-
VISION TEST
Your eye-sight must be checked before using the INSPIRATION, wearing your normal dive mask.
MUST BE READ LESS THAN 16 INCHES (40cm) FROM EYES
INSPIRATION
Confirm 69 hrs
ELAPSED TIME
DIVE NOW?
CALIBRATE
Yes No
Confirm
OPEN O2 VALVE
CHECK DILUENT
LOW OXYGEN
MASTER 0.70
0.21 0.19 0.20
HDIM7AN ETWO
APQBC DIUWNM J
BX XJKZ XKA7JSNXC
SNCC NSCHKC
CHSJ55 DC
FHSD
UFAHAA LNBZNCZC
SDHC XBCBC
SDHCA SDN9CMC
A1JC NSDCM
PWI Z3NCMVC
-9-
SECTION 1
IMPORTANT INFORMATION
This Section describes some of the problems you may encounter in the early
stages of using the INSPIRATION
READ THIS SECTION BEFORE ENTERING THE WATER !
1.1
Gas
There are two 3 litre cylinders on board. One contains oxygen and the other a diluent or dilutant.
Normally, the oxygen is fed into the breathing circuit via a solenoid operated oxygen valve; the
diluent is fed in manually. The oxygen is added to replace metabolised oxygen and to maintain the
oxygen pressure during ascents and is an automatic process requiring you, the diver, to simply
monitor it. The purpose of the diluent is to dilute the oxygen concentration to enable us to safely
breathe the mixture in the breathing circuit (or loop) below 6m and also maintain the counterlung
volume during the descent. Once at your target depth the diluent is no longer used, that is until you
accidentally exhale through your nose- losing loop volume, or you descend again. This leaves a
useful reserve of gas for BC inflation, suit inflation, oxygen cell checks and OC (open circuit)
bailout.
The correct type of diluent is essential. Ideally, it should be breathable throughout the entire dive.
So, at the start, use normal diving quality breathing air in the diluent cylinder. This is suitable for all
depths down to your air diving limit (35 to 50m). Using a setpoint of 1.3, 50m is the maximum depth
with an air diluent. Below 40m Heliox or Trimix (with a max. END of 30m at 70m, reducing to an
END of 24m at 100m) is strongly recommended. Below 50m, Heliox or Trimix is essential. But,
let’s not consider diving deep with it just yet though. Let’s get the basics right first. Build up your
Closed Circuit experience gradually.
NEVER, NEVER use pure gases in the diluent cylinder such as pure Helium or pure
Nitrogen - when something as simple as a manual diluent flush could and most likely will
render you unconscious. The diluent MUST always contain a sufficient oxygen percentage
to sustain life.
When using a diluent with an oxygen percentage lower then 21% do not breathe the diluent open
circuit when in the shallows. Also, take extreme care if adding low oxygen percentage diluent to the
rebreather when shallow. If the oxygen controller is inoperative, for instance if it’s not switched on or
the O2 is turned off or the O2 cylinder is empty then you will go unconscious. Consider changing
your configuration and diving practise to eliminate this possibility.
1.2
Weighting
How much lead is required? When experienced you will find that you only need to carry the same
weight as you do when you dive with a single 15 litre cylinder. You would probably find it more
comfortable though, to move 2-3 kg from your weight belt and put it in the weight pocket on the top
of the unit. This aids in-water trim helping to keep you horizontal. During your first dives you may
experience problems descending, so insert 2-3 kg in the weight pocket in addition to your normal
weight belt. Using the counterlungs at minimum volume, i.e. just enough gas to take one full breath,
brings many advantages including a minimum lead requirement, a better swimming position with
reduced back strain and early warning of gas usage from the loop. If back pain is experienced then
consider moving weight from the weight belt to weight pockets on the unit.
- 10 -
1.3
Buoyancy Control
Buoyancy control will be different from open circuit and, whilst not being difficult, it does require
some thought. When you breathe from a rebreather your buoyancy does not change. Consequently
the dry suit or BC must be used for buoyancy control, as minor adjustments cannot be made by
inhaling or exhaling.
If a dry suit is worn then we recommend using only the dry suit for buoyancy control and we
recommend fitting a variable exhaust valve so this can be set for automatic venting during the ascent.
These are particularly good when used on membrane dry suits. If operating at a constant depth,
buoyancy control is much easier than open circuit, but the problems start when you conduct “sawtooth” profiles. With any obstruction in your path you should now consider swimming around it,
rather than over it. To go over the obstruction will almost certainly require venting of gas during
ascent and inflation on return to the original depth.
1.4
Familiarity of Controls and Harness
The harness is available in 4 sizes. It is important to have the correct size. If you need advice, contact
the factory.
Adjust all the straps to fit you prior to reaching the dive site. Ensure the inflator hose from your dry
suit, connected to the LP port of the diluent cylinder’s first stage, has a long enough hose to reach
your dry suit inflator.
Practise locating and operating all the rebreather and BC controls including:
i)
opening and closing the mouthpiece
ii)
opening and closing the oxygen cylinder valve
iii)
opening and closing the diluent cylinder valve
iv)
operating the diluent inflator
v)
operating the oxygen inflator
vi)
operating the variable exhaust valve (use the high pressure setting (rotate clockwise fully)
when testing for leaks and use the low pressure setting (rotate anticlockwise fully) during the
dive)
vii)
operating the BC’s inflator and exhaust valves
viii) locating and using the emergency open circuit regulators (both diluent and oxygen)
ix)
switching from low to high setpoint on the oxygen controller
x)
ensure the counterlungs will be held down on your shoulders and will not float up when in the
water. Failure to do so will result in greater breathing resistance and may cause the pressure
relief valve to vent when on the “Dive” pressure setting.
1.5
Understanding ppO2
The ppO2, or oxygen pressure, in the breathing circuit is what keeps you alive. A thorough
understanding of ppO2 is the most important aid to safe rebreather diving. You need to know what
happens to your ppO2 when you descend, when you ascend, when your work rate increases and what
risks are present at different stages of the dive. The following self check questions are designed to
validate your understanding of the system and its use. Answers are included in Appendix 3.
a.
What are the risks when you first enter the water?
b.
What risks may become apparent during a surface swim prior to the dive?
c.
During the descent what is usually seen on the ppO2 display?
d.
e.
How often do you expect the solenoid to operate during the descent?
Once below 20m what would be the effect of staying on the low (0.7bar) setpoint?
- 11 -
1.6
f.
Once on the bottom how often would you expect the solenoid to operate and for how long
would the oxygen inject?
g.
What is the effect on the ppO2 of adding diluent to the loop, for example after mask
clearing?
h.
If a diluent flush is carried out at:
10m what will be the ppO2 in the loop?
20m what will be the ppO2 in the loop?
30m what will be the ppO2 in the loop?
40m what will be the ppO2 in the loop?
i.
How often should you check your ppO2 whilst on the bottom?
j.
Why is it important to check your ppO2 prior to the ascent?
k.
As you ascend how often would you expect the solenoid to operate and for how long?
l.
How would this vary with ascent speed?
Setpoint Selection
At first, use the INSPIRATION’s default settings of 0.7 bar for the low setpoint and 1.3 bar for the
high. Use the low setpoint at the surface and for the whole descent, this helps to prevent the ppO2
from spiking. On the bottom, or once below 20 to 30m, switch to the high setpoint.
If you attempt to surface whilst using the High Setpoint Mode, continual inflation will be
experienced as you approach the shallows. If the high setpoint is 1.3, then from 3 m upwards the O2
controller will be continually injecting oxygen. If your setpoint is 1.5 then it will be continually
injecting from 5 m upwards. This continual inflation will bring you to the surface unless gas is
purged from the breathing loop. The cure is to select the Low Setpoint Mode before reaching the
critical depth, at approximately 6 m, or when you are about to leave the 4 m decompression stop.
If the ppO2 is much lower than the setpoint, a quantity of oxygen is fed into the breathing loop, which
may make you positively buoyant. This problem is experienced when the high setpoint is selected
during shallow dives, down to 10m . During these dives it is easier to continue to use the Low
Setpoint Mode. If the high setpoint is definitely required at these shallow depths, then gas will have
to be purged from the loop when positive buoyancy is experienced, until the gas in the loop is close
to the required setpoint.
Be sure to check you are using the High Setpoint once on the bottom, this is extremely
important on dives below 10m. Be sure to monitor the ppO2 to ensure that it is close to
the setpoint. Variations away from the setpoint will affect your dive planning for
decompression.
Remember: check the ppO2 display every minute. Know your ppO2 at all times!
- 12 -
1.7
Descending
At first you may find it difficult to submerge. The problem is that air is held in four locations: the
dry suit; the BC; the counterlungs; and in your own lungs.
Whilst on the surface, concentrate on removing air from the BC and dry suit. Once this is done then
the only air to be vented is that in your lungs and the rebreather’s counterlungs. By continually
breathing in through your mouth and out through your nose, you will quickly deplete the retained gas
and reduce the buoyancy. Depending upon your weighting, it may at this time be necessary to do a
“duck dive” in order to submerge. At a depth of 1 to 2 m you will attempt to take your first breath.
You will probably be unable to do so because of the external pressure squashing the counterlungs.
At this time you should press the diluent inflator with your left hand, operating it in short bursts until
you have sufficient gas volume to take full, deep breaths. Practise the use of the diluent inflator
before entering the water.
If the optional Automatic Diluent Valve is fitted and connected to the diluent supply, the diluent
addition will take place automatically on descent or whenever the loop volume is insufficient for
inhalation or to be more accurate the diluent addition will take place whenever the pressure in the
counterlung is substantially lower than the ambient pressure.
Descend slowly to avoid ppO2 overshoot. Normal descent speeds are possible using the low setpoint
but extreme caution must be taken if the high setpoint is used during descent.
At the 6m point carry out a check of your equipment for leaks by looking upwards for tell-tale
bubbles.
1.8
Mask Clearing and Pressure Equalisation
During the descent the pressure in your mask will have to be equalised by exhaling through your
nose. However, exhaling through the nose depletes the counterlung volume and should, therefore, be
kept to a minimum. During your instruction you will have been advised not to exhale through the
nose. However, it is beneficial to do so during familiarisation with the apparatus, in a safe
environment, to experience the effect this has on the counterlung’s volume, your ability to take
another breath and the importance of being able to properly locate the diluent inflator.
Remember: if you continually breathe out through your nose you are effectively on open circuit and
your gas endurance will be greatly diminished.
1.9
Mouthpiece
It is important to close the mouthpiece before removing it, both
underwater and on the surface. Failure to do so will result in loss of
buoyancy and water entry. Practise opening and closing this valve
before entering the water. The mouthpiece must be fully open in use to
prevent water ingress through the drain port.
1.10 Ascending
To prevent lung damage during the ascent when using open circuit equipment, you would simply
breathe out . Unfortunately, with a rebreather this will only increase the volume of gas in the
counterlungs. Unless air is vented during the ascent you will notice both the counterlungs inflating
and an increase in exhalation resistance. Eventually the variable exhaust valve will vent. The low
pressure setting on the exhaust valve has a release pressure below that which would over pressurize a
human’s lungs. However, you will find it difficult to control your ascent speed if you rely entirely on
this valve. It is therefore best to vent the loop yourself, before the overpressure valve operates. The
aim is to maintain neutral buoyancy and retain enough gas in the breathing loop for one full, deep
breath. When possible, practise your first ascents up a shot or anchor line.
- 13 -
There are three ways to manually vent gas from the loop:
1)
Dump air periodically using the pull cord knob on the dump valve, the same method as used
with a buoyancy compensator.
2)
Exhale through the nose. This is effective for dumping gas from your lungs but the pressure in
the counterlungs will continue to increase as you ascend, so it is important to continually
breathe gas from the counterlung and out through your nose. In practise, it is easier to exhaust
air around the outside of the mouthpiece, whilst exhaling. This dumps air from both the
counterlung and from the lungs simultaneously.
3)
One of the easiest methods is to simply hold the dump valve open for the complete ascent. As
the gas volume increases it is exhausted from the counterlungs automatically. However, you
must continue breathing.
Do not forget to vent gas from your dry suit and buoyancy compensator during the ascent.
1.11 Breathing Resistance
The Work of Breathing of the INSPIRATION meets the requirements of the EN14143 at a breathing
rate of 75 lpm at 40m with an air diluent and at 100m with a Trimix diluent providing the END is
24m or shallower. The over-the-shoulder counterlungs provide the least static lung pressures for
overall ease of breathing in each orientation of the diver.
Please note that the volume of gas in the counterlungs greatly affects the breathing characteristics.
The volume of gas in the counterlungs is controlled by you. Too much gas will make it difficult
to exhale and with too little it will be difficult to inhale. The ideal method is to retain only just
enough gas in the counterlungs for one deep breath.
Gas may be added to the counterlungs by using the diluent inflator located on the left counterlung,
the inhalation counterlung. Be sure to use this inflator and not the oxygen inflator on the right or
your dry suit inflator. Be sure to rehearse the operation of the diluent inflator before entering the
water. This is very important. Apart from the fact that it needs to be second nature to find it, you
need to ensure gas is flowing to this inflator before submerging.
1.12 Counterlung Choice
The breathing bags/counterlungs are available in two sizes - medium and large.
counterlungs according to your body size. See section 4.1 for more details.
Select the
1.13 Gas Consumption
Normally, for a 1 to 1 1/2 hour dive, the gas consumed from each cylinder will only be 30-40 bar per
dive. Much more than this and your close circuit diving techniques should be examined.
Exhaling through your nose: If you carelessly exhale often through your nose you lose gas from the
breathing circuit (the loop), you then have to add diluent to allow you to breathe, this lowers the ppO2
and so the oxygen controller opens the solenoid to bring the ppO2 back up to setpoint, so in fact you
use gas unnecessarily from both cylinders.
Swimming over objects uses gas: swimming over an object often requires a vent of gas from the
buoyancy compensator and/or counterlungs. If a vent from the counterlungs is necessary then diluent
addition will be required as you descend again back to your original level which weakens the ppO2 ,
so the oxygen controller compensates by adding oxygen to bring it back up to setpoint. Again you
use gas from both cylinders. Swim around objects if you can rather than swim over.
Ascents: The time when the system uses most oxygen is during the ascent. The ppO2 drops with the
decreasing ambient pressure and the oxygen controller opens the solenoid often and for longer
periods than during other times on the dive. You must vent the loop during the ascent but if you vent
the loop around your mouth then virtually all of the fresh oxygen added by the solenoid is dumped
overboard, a big waste of gas. What you should do, particularly if the oxygen supply is diminished is
- 14 -
use the pull cord dump valve to vent the loop. This way some of the fresh oxygenated gas is used for
metabolism and some goes back around the loop to raise the ppO2 around the oxygen sensors,
reducing the opening time of the solenoid for the next injection and increasing the time between
injections.
Dry Suit: your dry suit dump valve may be exhausting accidentally when you roll over.
Learn to look out for gas leakage in addition to often checking the gauges. Do not be lulled into a
false sense of security and do check the gauges regularly.
1.14 System Integrity - Leaks
It is extremely important to cure any leaks before diving. A small leak is irritating and saps
confidence.
Be aware that it is very unusual to lose buoyancy or gas from the breathing loop. If there is a
constant need to inject diluent to breathe from the bag then it is very likely that there is a leak in the
system. The other problem is that this constant injection of diluent lowers the ppO2 in the loop,
making your decompression schedule invalid.
Test the complete apparatus for positive pressure leaks by closing the exhaust valve by rotating it
clockwise to the pre-dive/test position and either inflate by mouth, closing the mouthpiece
afterwards, or by using the diluent inflator. One of the most practical methods of testing for leaks is
to inflate the system using the diluent inflator until the pressure relief valve operates. If the
counterlungs remain firm for over 40 minutes then there are no significant positive pressure leaks on
the system. Ensure the exhaust/pressure relief valve is set to the low pressure position (fully anticlockwise) prior to diving.
Test with negative pressure by sucking a vacuum on the apparatus, crush one or two of the
convoluted hoses whilst sucking the vacuum and then close the mouthpiece. If air leaks into the
system the crushed hoses will spring back towards their original shape. It is extremely important to
find any small leaks and rectify them before diving. Water will ingress into the apparatus through
the smallest of leaks.
Water in the exhale tube will be apparent because of an audible gurgling noise. If, despite
continually clearing it by closing the mouthpiece, holding the mouthpiece overhead and shaking it,
water is still apparent, it may be entering around the outside of the mouthpiece. Also confirm the
mouthpiece is fully open. As the mouthpiece is opened and closed, an O ring seal which is used to
seal the inner tube against the outer, will be seen. If the mouthpiece valve is only partially open, an
O ring will be visible when viewed through the mouthpiece and water will be allowed to enter the
loop from the water vent. Finally, ensure the mouthpiece ty-rap is secure. Incorrect tensioning
during replacement could result in a leak.
It is important to keep the unit upright if water is suspected to have entered the
scrubber. If it can’t be stood upright lie it face down on it’s counterlungs, not on it’s
back. Lying face down and upright prevents the Sofnolime and water from damaging
the oxygen sensors, shorting the batteries or corroding the wiring.
1.15 Check for Water
During a dive it is good practise to periodically check for water ingress: roll on your left side and
then roll on your right side, exhaling in each position. If gurgling can be heard when on your left, the
water is most likely located on the exhale non-return valve in the mouthpiece, and this is best moved
by rolling on your right side, and then go slightly head up. The water will then pour into the exhale
counterlung and it can stay there for the duration of the dive. Shaking the exhale convoluted hose at
the same time will help any small water drops on their way. If gurgling can be heard when on your
right side, the water is most likely in the bottom of the scrubber. Care must be taken at this stage not
- 15 -
to go head down as this will allow water to flood through the sofnolime, dumping a Calcium
Hydroxide and Salt/chlorine water combination over the oxygen sensors, batteries and wiring which
will need careful cleaning before further use. Momentarily swimming on your right whilst exhaling
and listening for gurgling is a good test to do as you swim back to the boat, gurgling when on your
right means you have water in the bottom of the scrubber and you will need to advise the crew to
NOT lie the rebreather down.
1.16 Flooding and Clearing Drills
Small quantities of water stuck in the exhale hose may be moved into the exhale counterlung using
the technique in the paragraph above (rolling on your right and tipping up). A more thorough
technique is to remove the closed mouthpiece, hold it above your head and either shake the hoses or
simply stretch them slightly to get any water out of the convolutions.
During training it is necessary to conduct flooding and clearing drills. Do these at the end of a pool
session. During these drills, try not to allow water into the scrubber but if water is allowed in STAY
upright, get out and drain the scrubber BEFORE lying it down.
Something to remember during the drill: the water trap in the exhale counterlung cannot do
its job if the counterlung is sucked flat, so always leave some gas in the exhale counterlung.
If you don’t, water coming in from the mouthpiece will go straight into the scrubber instead
of the exhale counterlung.
1.17 Water Management
Firstly drain all the water from the rebreather prior to the dive. Particular care should be taken just
after disinfection. Any disinfectant must be fresh water rinsed from the rebreather prior to diving and
particular attention must be paid to ensure the inhale counterlung is dry. It’s a bit disconcerting to
inhale water as soon as you do a duck dive.
Try not to allow water into the loop at all. This is best achieved by ensuring the rebreather is leak
proof before getting in the water, ensuring the mouthpiece is not removed when it’s open, ensuring
the mouthpiece is fully open when breathing from the loop and ensuring you don’t allow water in
around the mouthpiece.
If water is allowed in, it needs to be moved out of harms away into the exhale counterlung. The
exhale counterlung can take quite a lot of water without impeding the breathing. Once you have
water in the exhale counterlung though, avoid swimming head down as this will allow water to work
around the water trap and enter the scrubber.
Although it is quite okay for a small amount of water to sit in the bottom of the scrubber it can start
to impede breathing, gurgling will be heard particularly when swimming on the right side (the bottom
opening of the side tube is covered with water). It is important for the scrubber’s side tube to be
against the diver’s back, so it does warn the diver of the water presence.
If the quantity of water in the bottom of the scrubber needs to be reduced slightly you could lean
forward slightly and slowly and allow the used Sofnolime at the bottom of the scrubber to soak up
some of the excess water. Never tilt forward far enough for the water to run downhill through the
Sofnolime.
Is there too much water in the loop? – water increases the breathing resistance, if you are finding it
hard to breathe you have to either bail out to open circuit or clear the water.
If In doubt – bail out.
- 16 -
Notes:
1) Try not to allow water in.
2) If you allow water in move it into the exhale counterlung and try to keep it in there.
3) Try not to allow it to go further round the loop into the scrubber.
4) If water gets into the scrubber, ensure it is not allowed into the top of the scrubber, stay upright
preferably or lean slightly forward and allow the water to soak into the used Sofnolime.
5) Under no circumstances go head down.
6) If large quantities of water continue to enter the loop, eventually it will be virtually impossible to
breathe and this is indicated by the exhale counterlung being completely inflated and the inhale
counterlung being completely deflated.
1.18 System Integrity - Indications
Know your ppO2 at all times! Learn how to evaluate the information provided by the oxygen
controllers - Section 3.5 to 3.5.6, Sections 6, 7 and 9.
Listen out for the solenoid. It should be operating in short bursts. If you think it has been open
longer than normal or it has not been heard for a long while - it is time to take a look at the ppO2
display.
Compare the cell readings. While breathing, the cell readings change. Bearing in mind that these
oxygen cell readings are shown in real time, the ability to see all three sensors simultaneously is a
great diagnostic aid. If one is failing to react as quickly as the others, there may be water on the
cell’s sensor face. The modifications made to the sensors prevent large quantities of moisture
reaching the face and affecting the internal circuitry. It is, therefore, essential to use only oxygen
cells supplied by Ambient Pressure Diving.
1.19 Batteries
Each oxygen controller has its own battery and circuitry. However, both
batteries share the same battery box door, so it is imperative to ensure this door
is fastened properly. The 6 volt Lithium batteries - Fujitsu or Energiser CRP2
are readily available. The battery life varies from diver to diver due to the
frequency of use of the backlight and the brightness setting. Assuming you
follow the sensible procedure of always using one handset as Master and
discarding the battery in the Master’s slot when the low battery level is reached, replacing it with the
battery from the Slave’s slot and inserting a new battery into the Slave’s slot, you can expect to put
one new battery into the Slave’s slot approximately every 17 hours.
The controllers do not automatically power down when not in use. It is, therefore, very important
to ensure that both controllers are switched off after use to preserve battery life.
1.20 Surface Swimming
When swimming forward, face down, on the surface, only partially inflate the BC. Over inflation
will cause increased body angle and extra drag. Deflate the BC and adopt a horizontal, head down,
streamlined swimming position.
1.21 Surface Buoyancy and Trim
By rotating the counterlung’s pressure relief valve to the high pressure setting, and with the
mouthpiece closed the counterlungs can be inflated and used for additional surface buoyancy. The
volume of gas admitted to the BC must be regulated to ensure an upright floating position.
1.22 Quick Post-Dive Checks
Check the exhale counterlung for residual water by unscrewing the oxygen inflator, see Section 4.6.
If water is present, drain and check the downstream side of the first water trap. If water is present,
- 17 -
remove the scrubber and check the Sofnolime at the bottom of the scrubber. If it is soaked replace
the Sofnolime before the next dive.
It is important to keep the unit upright if water is suspected to have entered the
scrubber. This prevents the Sofnolime and water from damaging the oxygen sensors,
shorting the batteries or corroding the wiring.
1.23 Practise
Learn to ascend without adding diluent. This enables you to surface normally, even in the event of
having lost your diluent gas for some reason, perhaps you’ve given it to your dive buddy?
Learn to operate the system with the solenoid failed in the closed position. This may be achieved by
manually adding O2 to reach a ppO2 of 0.9 when a ppO2 of 0.7 is selected.
Learn to operate the system with the solenoid failed in the open position. Practice this in the
swimming pool by selecting a high set point of 1.5 and controlling the injection of O2 by opening and
closing the cylinder valve.
- 18 -
1.24 Solenoid operation and the main oxygen risks during the dive
PHASE
NORMAL
SOLENOID
OPERATION
Surface breathing
Closed 6 secs, Open < 1
sec when the ppO2 is
close to and below the
setpoint
Jumping In
Closed 6 secs, Open < 1
sec when the ppO2 is
close to and below the
setpoint
On the surface
OXYGEN RISKS
POSSIBLE CAUSES
CONCLUSION
Hypoxia – HIGH risk
Hypoxia – oxygen cylinder valve
closed, oxygen cylinder empty,
solenoid jammed shut, oxygen
controllers switched off.
Before the decent there is only one oxygen risk –
Hypoxia or low oxygen pressure. Hypoxia can
occur within a minute or so when on the surface.
Look often at the ppO2 displays! Listen for the
oxygen injecting.
Hyperoxia – NO risk
Closed 6 secs, Open < 1
sec when the ppO2 is
close to and below the
setpoint
Hypoxia – No risk
Descending
Closed
* Hyperoxia – SLIGHT
risk
Bottom portion of
dive
Ascending
Closed 6 secs, Open < 1
sec when the ppO2 is
close to and below the
setpoint
Hypoxia – LOW risk
Closed 6 secs,
Open > 1 sec
Hypoxia – HIGH risk
Surface swimming
Closed 6 secs, Open <
1sec when ppO2 is close
to and below the
setpoint
Hypoxia – LOW risk
Closed 6 secs, Open < 1
sec when the ppO2 is
close to and below the
setpoint
Hypoxia – High risk
Hypoxia – oxygen cylinder vale
closed, oxygen cylinder empty,
solenoid jammed shut, oxygen
controllers switched off.
Hyperoxia – manual addition of
oxygen or solenoid jammed
open.
Hypoxia – the ascent is potentially a very
dangerous time. Check your ppO2 BEFORE the
ascent and then often during. Listen for the
solenoid, you expect long bursts of oxygen
addition – the opening time will vary with your
ascent speed but at normal ascent speeds it will be
approx. 4 or 5 seconds followed by 6 seconds
closed. This can rise to 17 seconds open, 6
seconds closed! Hyperoxia – there is a reducing
risk of hyperoxia as you ascend.
Hypoxia is a low risk simply because it takes so
long to happen and you should be looking at the
ppO2 displays, ensuring your ppO2 is close to the
(HIGH) setpoint to ensure you don’t suffer
decompression stop – ensure you stay within the
NO AA CNS guideline.
Hyperoxia – MEDIUM
Hyperoxia – NO risk
The main risk during the descent is the diluent. Is
the diluent switched on? – Check this before you
get in the water! Are you pressing the diluent
button or the oxygen button? Left hand is diluent.
(LEAN – left, RICH – right) Listen for the
solenoid, it shouldn’t be opening. If it does,
check the ppO2 displays.
Hypoxia is a low risk simply because it takes so
long to happen and you should be looking at the
ppO2 displays, ensuring your ppO2 is close to the
(HIGH) setpoint to ensure you don’t suffer
decompression sickness. Listen for the solenoid,
you expect short bursts with 6 closed periods. If
it is adding oxygen for longer than a fraction of a
second then check your ppO2 displays.
Hyperoxia – HIGH risk
Hyperoxia – MEDIUM
risk
Decompression
Stop
* Hypoxia – No risk, providing
the oxygen content of the diluent
is suitable for the shallows.
Hyperoxia – manual addition of
oxygen or solenoid jammed open
Hypoxia – oxygen cylinder valve
closed, oxygen cylinder empty,
solenoid jammed shut, oxygen
controllers switched off.
Hypoxia can occur within a minute or so when on
the surface. Look often at the ppO2 displays!
Listen for the oxygen injecting.
Do use the checklists at the back of this manual to aid preparation.
- 19 -
- 20 -
Danger of High O2
Bigger Star = Bigger
Risk
Listen for
Solenoid
Set/Check
High Setpoint
Cells Moving?
Cells Moving?
PO2 =
2.55?
Listen for
Solenoid
Listen for
Solenoid
Keep
checking
Did I check?
CNS limit?
1.3 bar-3 hours, 1.4
bar-2½ hours
Did I check?
Graphics original by Lynda Weller
Check Display
Check Displays
every minute
Listen for
Solenoid
Danger of Low O2
Bigger Star = Bigger
Risk
EMERGENCY DRILL!!
Check Display
Listen for Solenoid
PO2?
PO2?
OXYGEN DANGER POINTS
SECTION 2
DEFINITIONS
AMBIENT PRESSURE:
That pressure surrounding the diver/rebreather. Rough values are 1.0
bar at the surface, 2 bar at 10m, 3 bar at 20m, 4 bar at 30m etc. When
calibrating the cells prior to diving, the ambient pressure is the
atmospheric pressure on the day. This varies with altitude and weather.
BAILOUT:
An emergency breathing system.
BREATHING LOOP:
The entire breathing gas pathway including the diver’s lungs and
airways; the mouthpiece; the counterlungs; the convoluted hoses; and
the scrubber.
CALIBRATION:
All the oxygen cells have to be calibrated before use. This is a fairly
simple procedure; it takes about 25 seconds to complete and is done on
the complete unit prior to the dive.
CARTRIDGE:
Sofnolime is retained in a diver-refillable container/cartridge which is
inserted into the scrubber.
CCR:
Closed Circuit Rebreather.
CNS OXYGEN TOXICITY: Central Nervous System Oxygen Toxicity. Oxygen toxicity is a
combination of oxygen pressure and time. The exposure limits are
shown later in this manual.
CELL WARNING:
This is displayed when the ppO2 reading of one oxygen cell deviates by
more than 0.2 bar from the average of the other two. On the
INSPIRATION a Cell Warning is given if any or all of the three oxygen
readings are invalidated and so excluded from the ppO2 calculation.
CNS OXYGEN TOXICITY: Central Nervous System Oxygen Toxicity. Oxygen toxicity is a
combination of oxygen pressure and time. The exposure limits are
shown later in this manual.
CO2:
Carbon Dioxide gas, a constituent of the exhaled gas mixture,
poisonous if inhaled.
DILUENT:
Gas used to dilute the oxygen in the breathing circuit to reduce the ppO2
and allow dives below 6m. Usually air for dives to 40m.
E N D:
Equivalent Nitrogen Depth, used for determining the narcotic element
of Trimix and critically determines the density of the gas in the
breathing circuit.
HELIOX:
Gas used as a diluent consisting of Oxygen and Helium.
HIGH OXYGEN:
This is displayed when the ppO2 in the loop is 1.6 bar or higher.
HYPERCAPNIA:
An excess of carbon dioxide.
- 21 -
HYPEROXIC:
For the purposes of this manual, hyperoxic is classed as all breathing
mixtures with a ppO2 greater than 1.6 bar.
HYPEROXIC MYOPIA:
Short sight requiring corrective lenses, as a result of exposure to
elevated oxygen pressures over time.
HYPOXIC:
When the ppO2 is less than 0.16 bar.
LOOP:
The Breathing Loop, or breathing circuit, includes the diver’s lungs, the
mouthpiece, all convoluted hoses, counterlungs and scrubber.
LOW OXYGEN:
This is displayed when the ppO2 in the loop is 0.4 bar or less.
OTU:
Oxygen toxicity unit.
OXYGEN CELLS:
Cells or sensors used to monitor the ppO2 in the breathing circuit
(loop).
ppO2/PO2:
Partial pressure of oxygen in the breathing gas - this you have to
understand. It is the pressure of O2 in the breathing gas that keeps you
alive, you have to ensure the oxygen pressure is kept within life
sustaining levels. To calculate the O2 pressure (ppO2) multiply the
oxygen % by the ambient pressure.
Air(21%
O 2)
10/52
O2
Depth(m)
0
ppO2
0.21
ppO2
0.1
ppO2
1
1
0.231
0.11
1.1
2
0.252
0.12
1.2
3
0.273
0.13
1.3
6
0.336
0.16
1.6
10
0.42
0.2
2
20
0.63
0.3
3
30
0.84
0.4
4
60
1.47
0.7
7
80
1.89
0.9
9
100
2.31
1.1
11
The ppO2 is shown here for three gasses, Air,
10/52 (10% O2 + 52% He + 38% N2) and pure
oxygen. It can be seen that when breathed open
circuit these gasses are un-respirable at some
depths: Air, from a ppO2 perspective, exceeds 1.6
bar at about 66m. The 10/52 will not support life
in the shallows – you wouldn’t want to breathe
from this gas, with a moderate work rate
shallower than 10m. Pure oxygen exceeds 1.6 bar
at 7m and becomes increasingly toxic the deeper
you go.
PULMONARY OXYGEN TOXICITY:
Whole Body oxygen toxicity from long dives over multiple days
exposed to high oxygen pressures, see Hyperoxic Myopia.
SCRUBBER/CANISTER:
The complete, back mounted, canister used for CO2 removal and, in this
rebreather, oxygen analysis and oxygen addition.
- 22 -
SETPOINT:
The pre-selected setting about which the oxygen controller attempts to
maintain the actual ppO2 in the breathing loop.
SOFNOLIME:
The absorbent used in the scrubber to remove CO2 from the exhaled
gases.
TRIMIX:
Gas used as a diluent, consisting of oxygen, helium and nitrogen. See
Appendix 7.
LUBRICATION:
Any approved oxygen compatible grease. DO NOT USE silicone or
hydrocarbon based grease or oil on high or medium pressure oxygen
fittings.
- 23 -
SECTION 3
OPERATIONAL CONSIDERATIONS
3.1
General
The INSPIRATION is a closed circuit rebreather (CCR) in which the exhaled gases are recirculated
within the apparatus so the diver can breathe them again and again. A CO2 scrubber chemically
removes the CO2 whilst the oxygen controller monitors the exhaled gases and, when necessary,
injects oxygen to maintain the oxygen partial pressure (ppO2) at preset levels, known as setpoints.
Oxygen is supplied directly from a cylinder containing pure oxygen. As the diver descends, gas
needs to be added to maintain the breathing volume. Providing this gas has a lower oxygen content,
this gas dilutes the oxygen and is known as a dilutant or diluent. By diluting the oxygen the diver
can go deeper than the 6 m limit set for pure oxygen closed circuit rebreathers.
The INSPIRATION’s depth limit is governed by three factors. The first is the gas used as the
diluent, the second is the volume of bail out/emergency breathing gas and the third limit is the
greatest depth at which the rebreather has been formally tested - 100m, (depth is a significant factor
affecting the duration of the scrubber). If air is used as a diluent then the INSPIRATION can be used
at all depths down to the air diving limit, normally 40 to 50m. Air is the diluent of choice for normal
sport diving depths. Normal diving-quality compressed air is used.
Beyond 40m, Heliox or Trimix are preferred diluents. Deeper than 50m a diluent of Heliox or Trimix
(with a max. END of 30m at 70m, reducing to an END of 24m at 100m, see Appendix 7) is essential.
If Trimix or Heliox is used as a diluent then, as with open circuit diving, the gas mixture limits the
depth. It is not the intention of this manual to teach the diver how to dive using a pre-mixed helium
based diluent, a separate course should be undertaken for that, but it is essential to prepare a diluent
with a suitable Equivalent Nitrogen Depth (END) and a ppO2 lower than setpoint if the diluent were
to be breathed open circuit on the bottom or manually flushed through the breathing circuit.
The volume and type of bailout gas carried is extremely important in determining the depth range. It
must be sufficient in order to breathe at depth and bring you back to the surface. Some deep mixes
will not be respirable near the surface when breathed open circuit and in these circumstances an
additional means of breathing life support gas must be provided. See Appendix 7 for Trimix and
HeliAir mixes.
Refer to “Depth Limitations, Technical Data, Section 15.
The INSPIRATION is CE approved to 40m using an air diluent and 100m using an Heliox diluent or
Trimix (with a max. END of 30m at 70m, reducing to an END of 24m at 100m).
The INSPIRATION is designed to be used only with a separate face mask and mouthpiece. It must
not be used with an oral/nasal full face mask. If experimenting with full face mask configurations the
diver must ensure the INSPIRATION’s original mouthpiece is retained and inserted in the diver’s
mouth.
- 24 -
3.2
Gas Consumption
Only a fraction of the air we inhale, approximately 4% at the surface, is used, most of which is
converted into CO2 and exhaled along with the 96% of the gas not used. By recirculating the exhaled
gases, removing the CO2 waste product and replenishing the oxygen, we can limit the gas removal
from the oxygen cylinder to the same volume that we consume for metabolism, between 0.5 and 3.5
litres per minute depending on the person and work rate. Mr. Average consumes approximately 1
litre of oxygen per minute, women generally less. This means the 3 litre cylinder filled to 200 bar
contains 600 litres of oxygen and will last 10 hours, not allowing for extra O2 used during ascents or
reserves.
The other incredibly significant benefit for the diver is that the amount of oxygen consumed is the
same at all depths as shown in Table 1.
Table 1. Comparison of Gas Consumption between Open Circuit and Closed
Circuit Apparatus (for a diver with a breathing rate of 25 litres per min)
Depth (m)
0
10
20
30
40
50
60
70
80
90
100
Absolute
Pressure (bar)
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10
11
Gas consumption (litres/min.)
Open Circuit
Closed Circuit
25
50
75
100
125
150
175
200
225
250
275
1.11
1.11
1.11
1.11
1.11
1.11
1.11
1.11
1.11
1.11
1.11
Diluent is used for volume make-up during descent phases. Once at the target depth no more diluent
is used unless the breathing volume is reduced by gas wastage such as mask clearing or exhaling
through the nose at which time more diluent will need to be added to the counterlungs to enable the
diver to breathe without restriction. Diluent usage therefore, for the rebreather, is minimal.
Typically, if the diluent is used for BC inflation, dry suit inflation as well as counterlung inflation a
diver will only use 30 bar from the 3 litre cylinder per dive.
Diving with a full 3 litre cylinder, filled to 232 bar, it is clear the remaining 200 bar of this 3 litre is
available as emergency reserve or open circuit bailout.
Diluent usage should be monitored and recorded during the training dives to use for future gas
planning.
Oxygen usage varies with diver work-rate, but is independent of depth, and is approx. 0.044 times the
diver’s Respiratory Minute Volume (RMV).
Extra oxygen is injected into the breathing circuit during ascent phases to maintain the ppO2. and
must be allowed for. Again 30 bar is a typical consumption rate for a one hour dive and 50 bar for a
two hour dive. However, your own O2 usage should be monitored and recorded during the training
dives to use for future gas planning.
- 25 -
3.3
Oxygen Benefits
Background:
Air at the surface is approximately 21% oxygen, 79% Nitrogen. The Absolute Pressure at the surface
is approximately 1 bar. According to Dalton the partial pressure of oxygen (ppO2) is 0.21 bar and
the partial pressure of the Nitrogen (ppN2) is 0.79 bar: 0.21 + 0.79 = 1.0 bar. Referring to Table 2
you can see the ppO2 and ppN2 at the different depths when breathing open circuit SCUBA. The ppN2
is simply derived from multiplying the ppN2 at the surface by the ambient pressure, i.e. at 10 m, the
ppN2 = 0.79 x 2 = 1.58. The ppO2 is calculated in exactly the same way, at 10 m the ppO2 = 0.21 x 2
= 0.42.
The oxygen partial pressure in the INSPIRATION is monitored by three oxygen cells. As the diver
is consuming the oxygen through metabolism, the partial pressure drops. Once it drops below a
predetermined level, known as the setpoint, a solenoid valve is opened and oxygen is added.
By controlling the pressure of oxygen in the loop we have the opportunity to maintain higher ppO2
levels than that experienced on open circuit, decreasing the decompression obligations and giving us
either increased no-stop time or an increased safety margin.
Table 2 shows a comparison between a diver on SCUBA, breathing air, and a diver on closed circuit
rebreather with a setpoint of 0.70 bar on the surface and a setpoint of 1.3 bar for the dive. Comparing
the ppN2 of open circuit AIR and the ppN2 when on closed circuit it can be seen that the closed circuit
diver has a lower nitrogen loading at all depths down to 50m. But it can also be seen that the
breathing mixture becomes richer in oxygen whilst ascending, reaching 100% oxygen at 3m. This
has the positive effect of giving the diver oxygen-rich decompression on every dive, resulting in
quicker off gassing of nitrogen.
- 26 -
Table 2
Comparison of Open Circuit and Closed Circuit Apparatus
Depth
(m)
Absolute
Pressure
(bar)
ppO2
(bar)
0
3
6
10
20
30
40
50
1.0
1.3
1.6
2.0
3.0
4.0
5.0
6.0
0.21
0.273
0.336
0.42
0.63
0.84
1.05
1.26
3.4
Open Circuit (AIR)
O2
ppN2
N2
%
(bar)
%
21
21
21
21
21
21
21
21
0.79
1.027
1.264
1.58
2.37
3.16
3.95
4.74
79
79
79
79
79
79
79
79
Closed Circuit
ppO2
O2 ppN2
(bar)
% (bar)
0.70
1.3
1.3
1.3
1.3
1.3
1.3
1.3
70
100
81
65
43
32
26
21
0.3
0
0.3
0.7
1.7
2.7
3.7
4.7
N2
%
30
0
19
35
57
68
74
79
Decompression
A constant ppO2 dive computer such as the Buddy Nexus can be used to take full advantage of the
INSPIRATION’s reduced-deco potential.
Alternatively: Constant ppO2 decompression can be calculated using a software program such as
DDPlan.
A set of tables, showing no-stop times, is at Appendix 4 of this manual. These have been calculated
on DDPlan for the standard 1.3 bar setpoint. It can be seen that the no-stop time for 20m with a
setpoint of 1.3 bar is 140 mins. This compares to 51 mins on AIR on a Bühlmann table.
Alternatively, a standard Nitrox dive computer can be adjusted to the oxygen percentage at the target
depth with the planned setpoint. With a setpoint of 1.3 bar the oxygen percentage in the rebreather at
30m is 1.3 divided by 4 = 0.32, i.e. 32%. Setting the dive computer to 32% would be a very
conservative way of calculating the decompression requirements because the dive computer would
assume a constant gas percentage at every depth, whereas much higher oxygen percentages would be
breathed during the shallower phases of the dive. In practical terms though this is a very easy
method to achieve long duration dives with all the benefits of breathing Nitrox. Using a Nitrox dive
computer is of most use when 3 or 4 dives are scheduled per day or multi-level dives are conducted.
3.5
Oxygen Controller
The controller consists of three oxygen cells, two control units with their own displays and batteries
and one solenoid valve for oxygen addition. Whichever control unit is switched on first becomes the
Master control unit and the second unit becomes the Slave. The status of the control unit, whether it
is a Master or Slave, is shown at the top of the display next to the setpoint. The Master unit controls
the oxygen solenoid and hence the breathing mixture whilst the Slave purely acts as a secondary
display but ready to take over if the Master controller’s power should fail. You can simulate this by
switching off the Master controller - the Slave becomes the Master within 1 second.
3.5.1 Accuracy of the Oxygen Controller
The oxygen controller displays the ppO2 as measured by all three cells. The accuracy is ± 0.05 bar
and this should be taken into consideration when dive planning. If the setpoint is 1.3 bar, assume
1.25 bar when calculating decompression and 1.35 bar when calculating oxygen toxicity time limits.
See section 6 for further information.
- 27 -
3.5.2 Oxygen Cell Life
The cell manufacturer does not guarantee the cell life, as it varies with usage. In the INSPIRATION
it is expected that the cells will last between 12-18 months. This largely depends on their treatment
and importantly the ppO2 the cell is stored in. Vibration, excess temperature, excess moisture and
direct sunlight can adversely affect the cells. It is not recommended to store the oxygen cells in a
sealed bag or in an inert gas but simply return the gas around the cells to Air (i.e open the scrubber
lid). When travelling to remote spots it is advised to take spare oxygen cells and batteries. However,
oxygen cells will be consumed even in their storage bag and eventually will be unusable. They will
last longer inside the bag than out but only marginally so.
3.5.3 Interpreting the ppO2 Displays
On initial power up, the output from the cells is compared. If they are outside the expected range,
cell failure warnings are displayed and the oxygen controller will not proceed to dive mode.
The oxygen controllers display the ppO2 measured by all three oxygen cells and display in the range
0.0 to 2.55 bar. Remember that the ppO2 level must remain between 0.16 and 2.0 bar to sustain life.
If 2.55 bar is seen on the display - do not hesitate - perform a diluent flush immediately and consider
reverting to open circuit. 2.55 bar on the display could indicate either a malfunction in the
electronics or a very high ppO2. In the latter case the ppO2 level could be very high indeed e.g. 6 bar
at 50m ! (The maximum displayable value is 2.55 bar)
MASTER 1.30
1.28 1.29 1.31
MASTER 1.30
1.35 1.33 1.30
MASTER 0.70
0.35 0.37 0.35
During the dive the oxygen controller controls the oxygen partial
pressure in the breathing loop by averaging the nearest two cell
output readings, i.e. if you have one cell reading 1.28, another 1.29
and the other 1.31, the cell displaying 1.31 will be ignored
and the ppO2 assumed to be 1.285. As it is below the setpoint, the
solenoid will open for a fraction of a second.
In this example the ppO2 is assumed to be 1.34 bar, i.e. above the
setpoint, so the solenoid will not open.
In this example the ppO2 is assumed to be 0.35 bar. Here it is a long
way below the setpoint so the solenoid will open for a number of
seconds.
The advantage of measuring the ppO2 in this manner is that if one cell is faulty it is ignored, that is
until the difference is greater than 0.2 bar in which case a cell error warning will be displayed and the
buzzer sounded. The oxygen controller will continue to control the ppO2 because it only needs two
functioning cells to work properly. Because all three cells are displayed simultaneously you can
assess the warning and see if it was just a pocket of oxygen affecting one sensor or the problem is
ongoing. Although the controller will function normally with one faulty cell and continue to
maintain the ppO2, if the problem persists, the diver should abort the dive.
- 28 -
Warning
Because the system averages the nearest two cells, it is important to be aware
that in the unlikely event of two cells failing simultaneously then the only good cell will be
ignored. Remember though, once one cell shows a difference greater than 0.2 bar a cell error
warning will be displayed. See Section 6.12 (Verification of ppO2) and 9 (Warnings and Remedies)
for more details.
By displaying all three cells simultaneously it allows you to instantly diagnose the problem. Any
slow reacting cells can be spotted, along with any physical faults such as a faulty connection to a cell.
If a cell reads 0.0 bar then a wire or connector has become disconnected. If a cell is inoperative abort
the dive and consider manual operation or bailing out. Excess oxygen in the loop may be prevented
by controlling the oxygen cylinder’s valve. If more oxygen is required, press the oxygen inflator.
See Section 11 - Emergency Procedures.
3.5.4 Effect of Moisture on the Cells
In use the atmosphere in the scrubber is virtually always humid. When the scrubber lid is removed,
after the dive, condensation and moisture will be evident. This cannot be avoided due to the moisture
created by the Sofnolime reacting with and removing the CO2 from the atmosphere in the loop.
Humidity levels have been considered when determining the accuracy of the information provided to
the diver, in the same way an allowance has been made for the effects of the inherent ± 1% accuracy
of the cell outputs. The accuracy of the oxygen controller’s reading is ± 0.05 bar, allowing for all
normal use errors.
However, large drops of water either on the front cell face or in the back of the cell may affect the
readings. Water on the cell’s sensor face tends to slow down the reaction of the cell to changing
ppO2 and water in the back of the cell tends to push the ppO2 read out higher. The cells used on
the INSPIRATION have been modified to help eliminate both of these problems.
When fitting replacements ensure onl y original parts are used.
3.5.5 Setpoint Selection
There are two setpoints. A low setpoint used when on the surface and for the descent and a high
setpoint used when on the bottom and for most of the ascent. The switch from low to high and back
again is done manually with the centre push button on the display (see Section 5 for details).
The setpoints are user selectable to match the type of diving planned. However, begin by using the
default values: a low setpoint of 0.70 bar and a high setpoint of 1.3 bar. With a ppO2 in the loop of
1.3 bar, the maximum duration of the set is 3 hours per exposure or 3.5 hours per day, when using the
NOAA oxygen toxicity limits.
The Absolute Pressure at the surface is approximately 1.0 bar, if a higher setpoint than this is selected
whilst still at the surface, the unit will continually inject oxygen, trying to reach the setpoint. Since
this cannot be achieved the result would be a waste of oxygen and battery power. Look out for this
and make sure a low setpoint is selected when at the surface.
In your Nitrox training you will have learnt about CNS oxygen toxicity and the NOAA exposure
limits. When selecting setpoints be sure to consider the oxygen toxicity limits as this is the primary
factor affecting the dive duration with the INSPIRATION, see Table 3.
- 29 -
Table 3
NOAA - CNS oxygen toxicity exposure limits
ppO2 (bar)
Exposure Limit per Dive
1.6
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.7
Exposure Limit per Day (mins)
45
120 (2 hours)
150 (2 ½ hours)
180 (3 hours)
210 (3 ½ hours)
240 (4 hours)
300 (5 hours)
360 (6 hours)
570 (9 ½ hours)
150 (2 ½ hours)
180 (3 hours)
180 (3 hours)
210 (3 ½ hours)
240 (4 hours)
270 (4 ½ hours)
300 (5 hours)
360 (6 hours)
570 (9 ½ hours)
3.5.6 Pulmonary Oxygen Toxicity
Prolonged exposure to oxygen in excess of 0.5 bar can lead to pulmonary toxicity which affects the
whole body. Normally sport divers would never achieve such high exposures. However, with a
rebreather such high levels may be achievable and it is necessary to ensure the limits are not
exceeded. As a rough guide - if you stay within the NOAA CNS guidelines then pulmonary oxygen
toxicity is only of concern during long duration dives over multiple days. e.g. 6 hours diving per day,
every day, (using a ppO2 of 0.9) for 14+ days. Check your dive times for risk of pulmonary oxygen
toxicity by consulting one of the technical diving organisations’ (IANTD or TDI) work books. Using
the higher ppO2 levels of 1.35, 1.45 and 1.55 the CNS clock is the limiting factor in all cases.
HYPEROXIC MYOPIA
WARNING! There have been instances of Myopia (near sight) occur as a result of diving,
every day for 2 weeks on rebreathers. Some reports have indicated that corrective spectacles
are required for three months. Some have reported a long-term shift to corrective lenses,
while others have reported a return to normality within 2 weeks. Anecdotal evidence suggests 3 to 4
hours of diving per day for 14 days is sufficient to cause Myopia. Divers over the age of 40 seem to
be more susceptible.
3.5.7 Oxygen Limits for Diving Operations
ppO2 LEVEL
EFFECT
0 - 0.10
0.10
0.12
0.16
0.21
0.40
0.70
1.30
1.40
1.60
COMA OR DEATH
Unconsciousness
Serious signs of Hypoxia
Minor signs of Hypoxia
Normal air environment at the surface
INSPIRATION LOW OXYGEN warning
INSPIRATION Default Low Setpoint
INSPIRATION Default High Setpoint
Recommended recreation limit
INSPIRATION HIGH OXYGEN warning
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
- 30 -
3.6
Duration of the CO2 Scrubber
The CO2 duration was determined using the DERA/QinetiQ unmanned test facility at Alverstoke.
Test conditions: Water temp: 3 to 4oC, Breathing rate: 40 litre/minute, CO2 rate: 1.6 litres/min. These
rates have been previously determined by QinetiQ, as an average breathing rate, averaging out work
and rest cycles.
Rule No 1 - Dive Planning The Sofnolime must be replaced after 3 hours of use for CO2 produced
at a rate of 1.6 lpm
Multiple Dives
The INSPIRATION’s scrubber can be used for multiple dives, providing the Sofnolime is not soaked
during a dive, bearing in mind the total timed used must not exceed 3 hours (for CO2 produced at
1.6 lpm ).
Effect of Depth
In trials depth has proven to significantly reduce the scrubber’s CO2 absorption capability.
Rule No 2 - For dives deeper than 20m, the diver must leave the bottom when the total time
breathed from the unit reaches 140 minutes (for CO2 produced at 1.6 lpm). e.g. If dive 1 is for
100mins and the 2nd dive is deeper than 20m, the bottom time of the 2nd dive must not exceed 40
mins. Check the decompression times for the 2nd dive to ensure the dive durations, when added
together, do not exceed 3 hours!
Rule No 3 - For dives deeper than 50m the diver must leave the bottom when the total time
breathed from the unit reaches 100 minutes (again this applies to CO2 produced at 1.6 lpm.). e.g. If
dive 1 is for 90mins and the 2nd dive is deeper than 50m, the bottom time of the 2nd dive must not
exceed 10 mins. Check the decompression times for the 2nd dive to ensure the dive durations, when
added together, do not exceed 3 hours!
Warning
1)
2)
3)
4)
5)
6)
7)
8)
9)
This information is based on using the 1.0 - 2.5 mm diving grade Sofnolime and tested using a water temperature of 40C and an
average CO2 production rate of 1.6 litres per minute.
Some people produce more than 1.6 litres per minute of CO2 and usage times must be shortened. Conduct personal oxygen consumption
trials at work and rest to determine your own CO2 production before use. Calculate your approximate CO2 production by multiplying your
oxygen consumption by 0.9 .
Never expect the Sofnolime to last longer because you are in warmer water but do expect it to last for a shorter period if used in colder
temperatures than 4 oC.
The design of the scrubber, not just the weight of Sofnolime, is a major factor in the duration, so these performance figures cannot be used
for determining the duration of another make of scrubber.
If other scrubber materials are used, such as 2.5 - 5.0mm Sofnolime, then these duration figures are invalid.
The performance of the scrubber was tested at the QinetiQ test centre on a fresh batch of material, taken straight from the manufacturer’s
packaging.
Material that has been left exposed to the atmosphere can appear to be satisfactory but in reality may only work for a short period.
The efficiency of the material may vary slightly from batch to batch.
The information given applies to Air, Trimix (with a max. END of 30m at 70m, reducing to an END of 24m at 100m) and Heliox diluents.
- 31 -
3.6.1 How do I know when the CO2 absorbent can no longer absorb CO2?
If fresh Sofnolime of the correct grade is used, then the time used can be recorded and compared to
the three rules above. Recording the time used is most important! It is the only practical way of
predicting the remaining absorbent life.
Warning DO NOT RELY ON COLOUR CHANGE
Some Sofnolime changes colour as it is used but this is only a guide as the material returns to
the natural colour after a time and is also temperature dependent.
Replace the Sofnolime if the material is soaked, do not attempt to dry it out.
3.6.2 Extra CO2 Considerations
If you intend to use the absorbent for subsequent dives, leave the absorbent in the scrubber and seal it
using the convoluted hoses. Do not remove and repack partially used absorbent, as CO2
breakthrough will occur much earlier than expected. When absorbent is removed from the CO2
cartridge, dispose of it immediately.
The CO2 cartridge is easily refilled by the diver. The normal weight of Sofnolime required is 2.45 kg
of 1 - 2.5mm (8-12 mesh) granule size, 797 diving grade, Sofnolime.
Some settling of Sofnolime will occur. A small amount of settling will be taken up by the spring
loaded base plate. Care must be taken if a long journey is undertaken between packing the cartridge
and diving with it. Always inspect the cartridge before the dive.
Warning
Hypercapnia, an excess of CO2 at cellular level, can become a problem in any
form of closed circuit rebreather diving. Reduced efficiency of the absorbent, channelling of
breathing gas through the absorbent due to poor packing of the absorbent during refill or if
the absorbent becomes wet, can lead to increased CO2 levels which can result in Hypercapnia. Other
possible causes include damaged or misplaced scrubber components or inverted non-return valves in
the mouthpiece. Be aware of an increased breathing rate, symptoms of confusion. If you don’t
remove yourself from the breathing circuit to an open circuit bail out for instance the following
symptoms or signs will ensue very quickly: severe tremors, loss of balance, dissociation or
unconsciousness.
Warning Early CO2 warnings, such as respiratory distress, are often not detected when
breathing oxygen at pressures higher than 0.21 bar and in particular, rebreathing CO2 in 1.0
to 1.3 bar of oxygen is known to offer virtually no physical warning to the diver and escalate
quickly to severe tremors and unconsciousness! - a good reason to remain within the scrubber times
stated earlier, do proper pre-breathes and to not dive alone.
Maintenance of the apparatus, including disassembly of the scrubber, is detailed in Section 10.
- 32 -
3.7
Symptoms Associated with Low and High Oxygen Levels, High
CO2 Levels and Oxygen Toxicity
The following is intended to be a brief overview. For further information we recommend studying
the IANTD, or similar, training organisation manuals.
Hypoxia Symptoms (Lack of oxygen)
Hypoxia is extremely dangerous and is potentially fatal. The warning signs are very slight and
hardly noticeable. Once the ppO2 drops below 0.1 bar, the diver will become unconscious. It is,
therefore, essential to monitor the oxygen controller at all times. Oxygen should be administered to a
victim as soon as possible but may not always be successful.
Hyperoxia Symptoms (excess ppO2)
Spastic Convulsions are not always preceded by warning symptoms. It is, therefore, essential to
monitor the oxygen controller at all times.
Central Nervous System (CNS) Oxygen Toxicity Symptoms:
Visual problems (focus, tunnel, spotty etc.)
Ears (ringing, abnormal)
Nausea (spastic vomiting)
Twitching (facial)
Irritability
Dizziness
Whole Body Oxygen Toxicity Symptoms:
Dry cough
Shortness of breath
Increased breathing resistance
Discomfort in chest
Hypercapnia Symptoms ( excess CO2)
CO2 convulsions are easily confused with oxygen convulsions and in an elevated ppO2 (above 0.21
bar) convulsions and unconsciousness are rarely preceded by warning symptoms. It is therefore
essential to change the sofnolime regularly and ensure correct assembly and operation of components
such as scrubber cartridge O ring, spacer and mouthpiece non-return valves.
Rare warning signs
Shortness of breath *
Headache *
Dizziness *
Onset of these symptoms can occur very
quickly and without warning:
Severe Tremors
Loss of Balance
Dissociation
Unconsciousness
* Warning: The first symptoms are not always evident when breathing oxygen above 0.21
bar. Wartime testing by the Admiralty’s Experimental Diving Unit proved that oxygen
breathed at 1.0 bar whilst exhaled CO2 was rebreathed resulted in severe respiratory distress
in only 3 out of 18 tested. The remaining 15 subjects suffered acute nervous symptoms or
signs i.e. severe tremors with loss of balance, dissociation & unconsciousness. These all
occurred between 200 and 380 secs from commencement. Don’t take risks with CO2!!!
- 33 -
SECTION 4
APPARATUS COMPONENTS
- 34 -
4.1
Counterlungs
Two sizes of counterlungs are available: medium and large. Both have sufficient volume for
breathing.
Select the breathing bags/counterlungs according to your body size. When wearing trousers with a
belt and a T-shirt, measure from the lower edge of the belt at the front over your shoulder and down
to the lower edge of your belt at the back. Take the measurement on inhale.
Under 115cm - Medium Counterlungs
Over 115cm - Large Counterlungs
This is only a rough guide. For expert advice please contact the factory, stating your height, chest and
waist measurements.
It is essential to keep the breathing bags/counterlungs down on your shoulders. They are prevented
from floating upwards by the Fastex buckle located on the lower edge of each counterlung. These
can be fastened to the special connection points on the INSPIRATION Harness. If these do not allow
the counterlungs to remain on the shoulders then either a smaller breathing bag, or the use of crutch
straps, must be considered.
4.2
Over-Pressure Exhaust Valve
This is a two-position valve with an additional manual override. In both the fully open (dive) and
fully closed (pre-dive) positions there is a mechanical stop and “click” lock. Fully closed (clockwise)
is the high-pressure setting, used for detecting leaks on the system and for providing positive
buoyancy when at the surface with the mouthpiece closed. Fully open (anticlockwise) is the lowpressure setting, used throughout the dive. On this setting the loop pressure is kept below the
maximum lung overpressure of 40 mbar. During the ascent, this setting may be too high for
comfortable exhalation so the valve has a pull cord exhaust fitted which can be either operated
intermittently or continuously during the ascent. The latter option has the advantage of keeping the
breathing loop volume at a minimum eliminating the possibility of the expanding gas in the loop
from adversely increasing the buoyancy. The other alternative is to exhale around the outside of the
mouthpiece during the ascent or to breathe out through your nose. If this hands free approach is
preferred then it is best to exhale around the outside of the mouthpiece as this exhausts gas from your
lungs and the counterlungs simultaneously.
It is essential to keep the counterlungs down on the shoulders to prevent the over-pressure valve
operating continuously.
Low Pressure Setting - DIVE
High Pressure Setting: for leak testing
- 35 -
4.3
Mouthpiece Valve
If the mouthpiece is removed while in the water, either underneath
or at the surface, water may enter the loop. The INSPIRATION is
tolerant of small quantities of water entering but excessive
quantities should be avoided by closing the mouthpiece before
removing it from the mouth. When re-inserting into the mouth,
blow out to remove the water from the water vent and, while
continuing to blow, open the mouthpiece valve. The opening and
closing of this valve is very important and must be practised on the
surface prior to diving. Unlike any other mouthpiece on the
market, the central body section rotates and moves independently
of the two outer sections which move together with the inner tube
of the mouthpiece valve. It is easier to hold the mouthpiece still, as
this is often in your mouth, and rotate the outer rings. They are
prevented from unscrewing by the two cross-head screws located
underneath. When servicing, do not attempt to unscrew the outer
sections without first removing the screws. Attempting to do so
may damage some components.
Located at each end of the inner tube is a non-return valve. These
are keyed to prevent incorrect assembly. However, it is good
practice to check the direction of gas flow and check the proper
operation of the non-return valves prior to using the rebreather.
This can be easily carried out by disconnecting the hose connectors
from the T piece and gently blowing and sucking against the
connector. The direction of gas flow for the INSPIRATION
rebreather is clockwise when looking down on the unit. i.e. you
exhale over your right shoulder. Therefore, when blowing into the
right hand side hose connector the non return valve will close and it
should open when air is sucked from the connector. The non return
valve on the other end of the mouthpiece inner tube should close
when air is sucked from the left hand connector and open when air
is blown into the connector. After reassembling the hose to the unit
check for correct operation by alternately squeezing the inhale and
exhale tubes as you inhale and exhale. Gas must come from the
left and go out to the right. You must not be able to inhale gas
from the exhale side and exhale gas into the inhale tube.
4.4
Breathing Hose Connectors
The hose nuts are simply unscrewed. The connections to the
scrubber and the T pieces are piston type seals and seal even when
slightly loose. These connections should be hand tightened onto
the shoulder to prevent accidental unscrewing. Ensure the O rings
are lightly lubricated and not damaged before re-assembly.
Each hose nut is fastened to the convoluted hose using screw on
connectors. These are larger versions of the connectors used to
clamp the convoluted flexible rubber hose on the range of BUDDY
Buoyancy Compensators.
They allow easy removal for
maintenance, they allow the hose to swivel at these joints and they
provide an extremely secure connection.
- 36 -
4.5
Colour Coding of Convoluted Hose Connections
The blue rings all signify fresh oxygenated gas from the scrubber. The left shoulder T- piece located
on the inhale counterlung has blue identification rings, as do the hoses connecting to it and the
connection in the centre of the scrubber lid. The non-return valve in the inhalation side of the
mouthpiece is also coloured blue.
1
3
2
5
4
4.6
Diluent and Oxygen Inflators
All inflators, oxygen, diluent and Buoyancy Compensator, are low
pressure inflators, sometimes referred to as medium pressure
inflators. They are designed to work with a maximum feed
pressure of 15 bar. See the First Stage Interstage Pressures,
Section 10.3. The inflator hoses connect to the low pressure ports
on the first stages.
It is essential not to confuse the oxygen components with their
diluent counterparts. See Section 10.7, Precautions When Using
High Pressure Oxygen. Both the diluent and oxygen systems must be checked for leaks prior to the
dive and this is best done by dipping the valve in a water bath.
The oxygen inflator has special lubrication and seals and has undergone special cleaning to make it
suitable for use with oxygen. It must only be connected to a hose supplying oxygen. As the
apparatus is worn the oxygen inflator must be on the right hand, on the exhale counterlung and the
diluent inflator must be on the left hand, on the inhale counterlung.
Both inflators are secured into a base fitting with a large, hand tight, moulded ring. By unscrewing
this ring slightly the inflator can be rotated to best align the feed hose.
- 37 -
The identification badge can also be rotated clockwise to ensure the writing is up the right way. If
these identification labels are lost over time, the type of inflator can be identified by the markings on
the underside. After any adjustment, tighten the outer ring.
By unscrewing the outer ring completely the inflator valve can be
removed. Care must be taken when removing it, as there is a large
O ring seal underneath it.
Removing the inflator reveals a very useful drain valve which
should be used after every dive to drain any water that has entered
the counterlungs. This port can also be used to help with washing
and disinfecting the inner bags of the counterlungs.
4.7
Automatic Diluent Valve (ADV)
The ADV is an optional feature. It replaces the inhale Tee piece on
the left shoulder counterlung and is usually fitted with the diaphragm
facing the diver’s head. The ADV is activated by a pressure
differential across the diaphragm and it supplies gas to the loop
(breathing circuit) whenever a substantial negative pressure is
experienced within the inhale counterlung.
The gas supply hose connects with a 3/8”UNF thread to the low
pressure port on a first stage or into the diluent portion of the
INSPIRATION’s manifold and connects to the ADV’s 300o swivel.
The swivel allows for the hose to be fed from the rear e.g. from the
manifold, or from the front, from a side mounted diluent cylinder. If
the side mounted cylinder needs to be removed in water the optional
in-water quick release connector is available. The ADV is an
upstream valve and can be used with 1st stages delivering 7 to 11 bar
(nominal 9.5 bar) above ambient and requires no adjustment. The
elastomeric diaphragm cover allows manual operation.
During descents it is normal for the ADV to add gas on nearly every inhalation. However, this is
most abnormal during all other phases of the dive. Normally the ADV adds gas to make the
counterlung volume breathable and then stops.
WARNING: If the ADV operates on every inhalation this is an indication of either poor
rebreather diving practice like exhaling through the nose or is a sign of some other leak from
the loop. Any extra diluent addition usually has the effect of reducing the ppO2 within the
breathing circuit and would be countered by the oxygen controller adding oxygen to regain the
setpoint. The danger of inadvertently using excess gas from both diluent and oxygen cylinders is
higher when using an ADV and extra monitoring of cylinder contents gauges should take place.
Located on the left shoulder, rolling left side down may force the ADV to add gas to the loop as will
rotating head down, when the gas in the counterlungs migrates upwards away from the ADV and
causes a negative pressure on the inside of the diaphragm. Whenever these manoeuvres are
undertaken you may need to run the counterlungs with a higher gas volume than normal.
- 38 -
4.8
Weight Pocket
When swimming along horizontally on open circuit inhale fully, hold your breath, and lie still. You
will notice that you are brought into an upright position. This is exactly what happens on a
rebreather. As we breathe in and out of the counterlungs, the buoyancy at the chest area is constant
which means you may find that you are constantly being brought into an upright position. To
counteract this effect, up to 3kg of lead can be inserted in the weight pocket on the top of the
rebreather. Normally, removing 2 kg from your weight belt and putting it on the top of the unit is
sufficient.
4.9
Buoyancy Compensator and Harness
A Buoyancy Compensator must be used with this rebreather. Do not use the counterlungs to control
your buoyancy.
A choice of 16 and 22kg wings have been developed for the INSPIRATION, in conjunction with the
INSPIRATION harness. The harness has 25mm Fastex buckles located low down at the front which
are used to hold the counterlungs down on the diver’s shoulders. Holding the counterlungs down is
extremely important and care must always be taken to ensure they are not allowed to float above the
diver’s shoulders. If this happens, breathing resistance will increase dramatically, probably causing
the diver some discomfort - if not immediately, certainly after a time. Increased breathing resistance
means increased CO2 retention, which is believed to make the diver more susceptible to oxygen
toxicity and nitrogen narcosis. If the counterlungs are floating off the shoulders, ensure the waist
band of the harness is not riding up. This is usually cured by simply adjusting the waist band. If it
cannot be secured, you may have to add a crutch strap or it may be necessary to change to a smaller
size counterlung.
See Section 4.1.
4.10 Auto Air
The Auto Air is fitted as standard to the buoyancy compensator. It is a multi-function valve, not only
is it the BC inflator, it can also be used for BC deflation as well as emergency breathing from the
diluent. Most importantly the Auto Air is also a pressure relief valve:
Should the 1st stage leak, the rise in intermediate pressure will automatically be relieved through the
Auto Air.
Note: normally, diluent is not used during the ascent. This means that the intermediate pressure
increases in relation to the ambient pressure as the diver ascends. The Auto Air will bleed off this
excess pressure automatically. It may appear that the Auto Air is leaking but all it is doing is
relieving the excess intermediate pressure. A simple purge is all that is needed to stop the gas
dribbling out or it can be simply left alone.
- 39 -
WARNING: it is essential that the Auto Air feed hose is not disconnected. If the Auto Air
continues to leak after a purge then simply close the cylinder valve, opening it whenever
you need diluent and then after the dive, check the intermediate pressure before adjusting
the Auto Air.
WARNING: disconnecting the Auto Air hose during a dive may result in an intermediate
pressure hose bursting – DO NOT DISCONNECT, simply close the cylinder valve.
WARNING: if the Auto Air is replaced with a conventional inflator and a conventional 2nd
stage, be sure to fit a downstream 2nd stage. If an upstream 2nd stage is fitted or a flow
control device such as the AP “Flowstop” is used then be sure to fit an additional pressure
relief valve to the intermediate pressure. The RB17 (14bar) is an example of a suitable
automatic pressure relief valve.
4.11 Audible Warning Device
The audible warning device or buzzer is located on the left shoulder T-piece
and is directed towards the divers head. This is only a secondary device, the
primary warning device being the ppO2 displays, and is not to be used as the
diver’s only warning system. All warnings: High O2, Low O2, Low Battery,
Cell Warning have the same sequence - 1 second on, 1 second off and
continue while the fault is occurring. The only exception to this is the Cell
Warning is deactivated when the solenoid is open. When the buzzer is heard
it is then the diver’s responsibility to assess the problem by interpreting the
ppO2 displays.
4.12 Oxygen Solenoid
In DIVE mode the oxygen solenoid is activated ONLY when the ppO2 is below the setpoint. The
oxygen solenoid is opened for a variable time, from 0.2 to 17 secs, depending on how far the ppO2 is
below the setpoint. Larger pressure drops, such as during the ascent, prompt longer solenoid opening
times to regain steady state setpoint as soon as possible. This variable open time is then always
followed by a 6 seconds close period, hence a slight delay (up to 6 secs) may be noticed before
expected solenoid activity but this is quite normal.
The “solenoid” consists of two major components:
The solenoid itself which is black and the chromed oxygen valve, the stem of which is inserted
through the solenoid and held in place by a circlip. The solenoid is a simple coil requiring an input
of 6 volts for activation. The solenoid draws approx. 350mA and as such is the largest power
consumer, the backlight being the 2nd heaviest power drain.
The oxygen valve is an “upstream” design. The gas pressure closes the gas outlet and holds it closed.
The gas pressure is critical for proper operation of the solenoid.
On the outlet of the oxygen solenoid a chromed restrictor buffers the oxygen flow into the scrubber
lid to prevent oxygen surges when the solenoid initially opens. This is particularly necessary during
deep dives. The restrictor should not be removed for diving. Occasionally the restrictor should be
unscrewed and checked for blockage. If the flow is restricted too much then calibration times will be
extended and solenoid activity will be increased to maintain a constant ppO2 , reducing battery life.
- 40 -
SECTION 5
POWER ON
Before you switch the electronics on, open the oxygen cylinder valve. The battery test is more
effective if there is gas supplied to the solenoid valve.
5.1
General
The INSPIRATION has two oxygen controllers, located in separate handsets, with separate batteries.
Whichever controller is turned on first becomes the Master controller. It is the Master controller
which controls the ppO2 in the breathing loop by monitoring the oxygen partial pressure and opening
the solenoid when necessary.
During the dive the setpoint can be changed from low to high and back to low ONLY on the
Master controller. The Menu mode can only be entered from the Master controller when in
LOW setpoint dive mode.
The flow charts detailed in Appendix 1 should be used in conjunction with this Section.
5.2
Switching On and Off
Switch On
Switching on requires two actions : Firstly push the lever switch towards the screen. Then push the
left slider towards the screen. This starts the display.
Switch Off
There are two techniques for switching off a handset, both hardware. If the centre and the right
sliders are pushed towards the screen and held for a second, the handset will switch off.
When switched off like this though, there is still a power drain of 5mA, so the lever switch should be
used if the unit is not going to be used for a few hours. Pushing the lever away from the screen
isolates the display from the power supply.
Screen Display -
A.P.DIVING
INSPIRATION
When the unit is first switched on, the screen display shows INSPIRATION and the buzzer gives two
quick beeps. This is the quick confirmation that the buzzer is functioning so listen out for it - your
life may depend on it.
At this stage switch on the Slave controller.
- 41 -
5.3
Oxygen Cell Check
Screen
Display -
CELL n FAILURE
REPLACE
CELL n FAILURE
MISSING
NO DIVE
The health of the three cells is checked on start up. If a fault is detected the screen will display CELL
n FAILURE, MISSING or CELL n FAILURE, REPLACE, where n is the particular cell in which the
fault has been detected. An open circuit or failed cell will result in the screen displaying the message
NO DIVE.
More extensive cell analysis takes place during calibration.
5.4
Battery Check
If the oxygen cells are functioning correctly the apparatus then carries out a check of the Master’s
battery. If the voltage is insufficient a low battery warning is shown. The Slave checks its own
battery when switched on.
Screen Display-
BATTERY WARNING
REPLACE
DIVE NOW?
Yes
No
On switch on, there are two levels of battery warning. At approx. 5.1 volts -BATTERY WARNINGis displayed with an option to dive requiring a YES or NO decision. It is recommended that if a near
the limits dive is planned, or if the apparatus had been stored at a low temperature, the battery should
be replaced.
If the second battery level warning - LOW BATTERY - is displayed during power up, the oxygen
controller will not continue into dive mode and the dive could not commence. This 2nd warning
comes in at approx. 4.7 volts.
Screen Display -
LOW BATTERY
REPLACE
NO DIVE
For low battery warning when in dive mode and temporary cure, see Section 9, Warnings and
Remedies.
5.5
Elapsed On Time
Screen Display -
ELAPSED ON TIME
nnHRS nnMINS
DIVE NOW?
CONFIRM
The display indicates the length of time, in hours and minutes, that the unit has been switched on
since the timer was last reset to zero. This elapsed time is reset from the menu system once the
controller is in DIVE MODE. This elapsed timer can be used to time any one of a number of events,
such as time since last battery change, or time since last scrubber change. This timer must only be
used as a guide, as the elapsed timer relies on the user resetting it. Also, as it may be reset at any
time, care must be taken to ensure that no-one inadvertently resets the timer without your knowledge.
The system requires confirmation, by pressing the middle button, to proceed to the next stage,
CALIBRATION.
- 42 -
5.6
Check Diluent
Screen Display -
CHECK DILUENT
CONFIRM
The controller then prompts Check Diluent. Open the diluent cylinder valve fully and press the
diluent inflator whilst watching the diluent pressure gauge. This checks all connections and that you
actually have gas to that valve. If the HP gauge needle moves when you press the diluent inflator
then the cylinder valve is closed and should be opened.
5.7
The Slave Oxygen Controller
This must be on at this time. The Slave’s battery and oxygen cell connections will be checked and
the same screen messages as shown in 5.2 and 5.3 will be displayed in the event of an error.
Whichever controller you turn on first is the Master, and the Master controls the oxygen level in the
loop. If the Master is not yet in dive mode and you turn the Slave on - the Slave checks the oxygen
cells and battery and then displays:
Screen Display -
SLAVE
WAITING FOR DATA
When the Master enters DIVE MODE and the solenoid is closed, the calibrated cell readings are
taken from the Master by the Slave. The Slave then uses these figures as the reference to selfcalibrate. The ppO2 for all three cells is displayed on the bottom line with SLAVE 0.7 on the top line.
The Slave simply takes the mVolt outputs from the same three cells as the Master controller. It
calculates the ppO2 values for itself, so it is common to see the Slave display varying from the Master
by ± 0.01 bar. If at any time the Master is switched off or powers down, the Slave recognizes this
and automatically becomes the Master, taking control of the solenoid.
Warning
The Slave MUST display “Waiting for Data” BEFORE the Master goes into
DIVE MODE. If the Master is already in DIVE MODE when you turn the Slave on, the
Slave will not perform the following vital checks: oxygen cells, connections and battery
checks. It will simply take the calibration figures from the Master and enter SLAVE MODE. (The
reason why the designers have allowed the Slave to skip these checks is to allow the Slave to be
activated whilst underwater, even if a fault like a low battery or faulty cell exists. The diver then has
the chance to verify which cells are giving accurate readings and which ones aren’t and to add
oxygen or diluent manually to maintain a life supporting breathing mixture.)
- 43 -
SECTION 6
CALIBRATION
The mVolt outputs from the cells vary with the ppO2. If the ppO2 is higher, the voltage will be
higher.
Even in storage a cell is continually working, measuring the oxygen partial pressure. This gradually
and continually lowers the output voltage. Consequently, the oxygen cells need to be calibrated at
regular intervals. On the INSPIRATION this is a simple procedure, taking about 25 seconds. Every
time it calibrates, the calibration factors are stored for future analysis of cells. Eventually the output
voltage of the cell is too low and it will need to be replaced. Calibrate every day of use. The
calibration sequence involves surrounding the cells with oxygen at a known pressure.
It is normal to calibrate before every dive. Valuable cell checks are included in the automated
calibration procedure.
6.1
Must Calibrate!
Screen Display
MUST CALIBRATE
YES
NO
-
The stored calibration coefficients of the cells are used to compare the current cell outputs. If
calibration is required the screen displays-MUST CALIBRATE! YES or NO. Normally, YES is
selected by pushing the button under YES. There are occasions though when NO would need to be
selected. For instance, if both controllers were switched off underwater and then back on again, unit
calibration would be disastrous. The calibration routine involves flushing the loop with pure
oxygen. Feeding pure oxygen into the loop at depth would result in a catastrophically high ppO2!
Calibrate on land, never in the water and never underwater. If you do switch the handsets off
underwater and turn them back on, you will be asked whether you want to calibrate. Always select
NO. If you accidentally press YES, then switch the handsets off immediately and start the switch on
sequence again.
6.2
Calibrate?
Screen Display -
CALIBRATE?
YES
NO
If the cell outputs were very close to the previously stored values then the screen display shows CALIBRATE? YES or NO. If the apparatus had only recently been calibrated then there would be
little point in recalibrating, but the option to calibrate is given. It is essential though to recalibrate at
least every 3 hours of diving.
- 44 -
6.3
Ambient Pressure
Screen Display -
AMBIENT PRESSURE
DOWN 1000mB UP
On selecting YES, the AMBIENT PRESSURE in mbars is requested. The default value is 1000
mbar ( 1 bar) every time the apparatus is switched on. The value may be increased or decreased
using the UP and DOWN buttons respectively. To accept the displayed figure press the centre button
once.
Warning
It is important to understand the implications of the selection. If an ambient
pressure of 1000 mbar is selected when the ambient pressure is really 850 mbar (0.85 bar),
for instance when diving at altitude, then the oxygen controller would be displaying a ppO2
of say 1.3 but the actual ppO2 in the loop would be 1.10 with the consequent effect of increasing the
Nitrogen loading. If this error was added to worst case accuracy of -0.05 the ppO2 level would be
only 1.05 bar! If the decompression times were calculated assuming a ppO2 of 1.25 bar
decompression sickness could result!
The opposite is also true. If the ambient pressure is 1050 mbar (1.05 bar) and the default value of
1000 mbar accepted then, in the worst case, this error together with the system tolerance of ± 0.05
bar, an indicated value of 1.3 bar in the loop could in reality be as much as 1.37 bar. At the lower
ppO2 settings this is not as critical but if a setpoint of 1.5 bar was selected, for which the CNS
Oxygen toxicity time limit is 2 hours, but there is actually 1.6 bar in the loop, for which the time limit
is 45 minutes, oxygen toxicity problems could arise.
6.4
Oxygen %
Screen Display -
OXYGEN %
DOWN
99%
UP
On accepting the ambient pressure value, the OXYGEN % is requested. It is requesting the oxygen
% in the scrubber lid after the oxygen inject takes place during calibration. This is as important as
the ambient pressure. If there is 80% oxygen in the lid and 100% is entered, then the oxygen
controller will always display the ppO2 1.25 times higher than its actual value. Again, a bend is
likely to occur. Typically a value of 98% would be entered when the oxygen cylinder contains 100%
O2 , the exact value can be determined- see section “Verification of ppO2 .”
Warning
The INSPIRATION is designed to be used with 100 % oxygen. Buying
100% oxygen is not too difficult in the UK. Diving oxygen is guaranteed by BOC or Air
Products to be 99.99% pure and is certified as such. Welding oxygen is not analysed. Care
must be taken with Medical oxygen as its oxygen content may vary depending on whether it will
used by midwives or by paramedics, or for other uses. There are grades of medical oxygen which
contain CO2! Specify diving oxygen. To determine the oxygen purity (when the gas quality is not
certified) - see Appendix 3
- 45 -
6.5
Open Mouthpiece
Screen Display
OPEN MOUTHPIECE
CONFIRM
Once the oxygen percentage has been selected and confirmed by pressing the centre button, the
controller prompts OPEN THE MOUTHPIECE valve. The reason for this is to enable the cells to
calibrate to ambient pressure and this would not be possible if the mouthpiece was closed.
Ensure the mouthpiece is open then confirm by selecting the centre button.
6.6
Open O2 Valve
Screen Display -
OPEN O2 VALVE
CONFIRM
The controller then prompts OPEN OXYGEN VALVE. Ensure the oxygen cylinder valve is open by
turning anticlockwise one or two turns then confirm with the centre button.
6.7
Flushing Bag
Screen Display -
FLUSHING BAG
0.34
0.27
0.40
The displayed ppO2 readings from the three cells will be seen to climb as the solenoid is opened and
oxygen is fed into the loop. Do not worry that all three are different - they will not be the same until
they are calibrated. The oxygen controller makes a number of checks during this phase:
6.8
No Oxygen - Check Valve
Screen Display
NO OXYGEN
CHECK VALVE
If the oxygen cylinder valve has not been opened then the mVolt outputs will not climb up to the
expected values and the controller would display the following warning: NO OXYGEN, CHECK
VALVE, NO CALIBRATION, NO DIVE. Opening the valve will allow the calibration to proceed.
Warning
Be aware - it is possible to fool the oxygen controller! After use there is a
high oxygen content in the loop. If the oxygen valve has been turned off and a second
recalibration is selected, the oxygen controller will recalibrate despite the fact that the
oxygen cylinder valve is closed. This will give an inaccurate calibration. What is more, the dive is
about to be commenced with the oxygen cylinder valve closed! You must ensure the gas mixture in
the loop is close to 0.21 bar before calibration! This is easily done by either breathing from the loop
or by flushing with diluent.
- 46 -
6.9
Cell Stuck
CELL STUCK
Screen Display -
This is displayed if the oxygen controller has seen no change in millivolt reading from a cell during
calibration. Flush the loop with air and then do the calibration again. If the same error message is
displayed the cell must be replaced before diving.
6.10 Out of Range
OUT OF RANGE
Screen Display -
This is displayed during calibration if one or more cells’ output voltages are too low or too high.
This prevents diving with cells with abnormal readings at atmospheric pressure and also prevents
inadvertent calibration whilst underwater.
CELL n FAILURE
OUT OF RANGE
REPLACE
NO DIVE
CELL n FAILURE
NO CALIBRATION
Should this occur, DO NOT dive, check the O2 % in the oxygen cylinder with a separate analyser,
check the atmospheric pressure and check the cell output in air by placing a digital DC voltmeter
across the outside two connector pins. The output should be in the range 8 to 13.5 mV.
6.11 Flushing Bag
Screen Display
FLUSHING BAG
0.34
0.27
0.40
The flushing bag process lasts until the cell outputs are stable.
Once the controller is satisfied with the cell outputs then the CALIBRATING message is shown.
Screen Display
CALIBRATING
6.12 Master
Screen Display:
MASTER 0.70
0.71
0.69
0.70
Once calibrated the display shows MASTER 0.70 on the top line and the three calibrated outputs
from the three cells below. These should all agree within ± 0.02 bar. This is called ‘DIVE MODE’.
- 47 -
6.13 Slave
Once the Master is in DIVE MODE and the solenoid is closed for 5 seconds, the SLAVE Oxygen
Controller changes from “Waiting for Data” to SLAVE MODE.
Screen Display:
SLAVE
WAITING FOR DATA
0.71
SLAVE 0.70
0.69
0.70
Once in SLAVE MODE it behaves as an independent, self-powered, secondary display. It calculates
the ppO2 using the data it takes from the oxygen cells. It is common to see the Slave display varying
from the Master display by as much as 0.01bar because of calculation rounding.
6.14 Verification of ppO2
Rule No.1 with any rebreather is “KNOW YOUR ppO2 - know what you are breathing”. Never,
ever, breathe from a rebreather unless you know what you are breathing.
There are three ways of knowing your ppO2 when diving a Closed circuit system.
i) Breathe from a pre-analysed open circuit supply. i.e. don’t use a rebreather
ii) Look at a ppO2 display
or iii) Flush the loop with fresh gas, usually a known diluent that is life sustaining at your depth.
Methods (i) and (iii) we can use in emergencies, so in normal use we have to use the ppO2 display to
warn of changes in ppO2 . The ppO2 you breathe is important not just for keeping you alive but slight
reductions in ppO2 may cause you to suffer decompression sickness ( you’ll get a bend).
Hopefully by now, you understand the importance of looking at the ppO2 display, so now it is
important to verify that the display is giving you accurate information.
6.14.1 Indicators to look for during calibration
i) Cell Reaction time?: Start with air in the loop. As oxygen is injected during calibration compare
the three cell displays to see whether they are all changing value at the same rate. If you have a slow
reacting cell, then it will result in a “cell warning” during the dive, especially during diluent flushes.
ii) Cell values prior to the “calibrating” message shown on the display: The cell readings must
be stable for a calibration to occur. Just prior to “calibrating” being shown on the display, read off
the values for all three cells and make a note of them - perhaps in the back of this manual. The cell
values are likely to be different and should lie between 0.7 and 1.35. When you do the calibration,
compare these “end” values with those recorded in your manual. In this way you can see whether the
sensor face is occluded or if the cell is starting to deteriorate (as we expect them to near the end of
the cells life).
iii) Cell Evaluation During Calibration: When they are new, the Oxygen cells used in the
INSPIRATION have an output of between 7.6 and 13 mVolts. With the Inspiration’s cell validation
routine, the calibration will be discontinued if the cell’s output is outside the range 7 to 13.5 mVolts.
If you see “cell out of range” on the display, the cell MUST be changed prior to diving.
If both handsets are switched off, accidentally or on purpose, whilst underwater, an option to
calibrate will be displayed. Either - “Calibrate Y or N” or “Must Calibrate Y or N” - you MUST
select “No”. If you accidentally say “Yes”, simply switch off and then switch back on again, go
through the selections until you reach the option to calibrate again. This time select “No”. If you
leave it to do the calibration the “Cell out of range” message will be shown, “No calibration”. This
- 48 -
prevents accidental calibration whilst underwater. At this point you should shut the handsets down
and either go onto open circuit or go through the switch on routine again, being sure to select “No” to
the calibration question. Please be aware though that during all this the oxygen pressure is not being
maintained by the oxygen controller, the ppO2 is dropping in the loop as you breathe - so do not
spend too long adjusting, get the display back into dive mode where Master 0.7 is displayed on the
top line.
The reason why you MUST NOT calibrate underwater :
During calibration a quantity of pure oxygen is flushed into the loop. If you are at 50m you will be
breathing 6 bar ppO2! Convulsions will occur quite quickly. Do the calibration procedure only when
you are on land, mouthpiece open, and NOT breathing from the loop.
The previous versions of electronics do not have the software to actually stop you doing a calibration
underwater so on these models, it is a limitation of use that you must understand. - YOU MUST
NOT CALIBRATE UNDERWATER !
iv) Time taken to calibrate: Due to the fact that the cell readings must be reasonably stable for a
calibration to take place, the time taken to calibrate will vary depending on the ppO2 in the loop prior
to calibration. A lower ppO2 at the start (0.21) will result in a longer calibration time than when
starting with a higher ppO2 in the loop. It is best to start with air in the loop and so you get a good
indication of how the cells are reacting to changes in ppO2 .
6.14.2 Periodic Calibration Check
During constant depth phases of the dive the ppO2 at the mouthpiece is held within a very tight band,
typically within ± 0.02 bar of the mean. (You will see bigger swings on the displays because they
show the oxygen pressure in the mixing chamber (the scrubber lid)). However, the accuracy of the
mean ppO2 depends on the calibration information you give it. If you enter the wrong values, the
ppO2 will still show that the oxygen level is around the setpoint (1.3) but the true O2 pressure will be
offset from the displayed value and this could be dangerous. The degree of danger depending on the
value of the offset and on the type of dive you are doing. If you are doing a “push it to the limits”
decompression dive, then you may get bent.
The accuracy of the calibration depends on the percentage of oxygen in the cylinder and the injection
rate of O2 into the scrubber lid. The oxygen injection varies slightly from rebreather to rebreather but
is something that is easily checked. After calibration open the mouthpiece slightly and operate the
oxygen inflator. Keep pressing the button until the ppO2 stops rising. Release the button and wait for
5 seconds before reading the values on the display. These should be reading the same as the
atmospheric pressure. Often, the readings will be slightly higher than that, so switch off the handsets,
flush the system with air and do the calibration again, this time entering a lower oxygen % than you
did last time. Repeat until you find the correct oxygen % to enter for your rebreather. Once you find
the correct oxygen% to enter for your rebreather, use that value from them on. Test it again at
monthly intervals and test whenever you change oxygen supplier or have any reason to doubt the
percentage of oxygen in the mixing chamber.
Important: the oxygen % asked for is the oxygen % in the mixing chamber (the scrubber lid), NOT
the oxygen % in the cylinder.
This method improves the accuracy of the ppO2 display but you should continue to use values of
setpoint ± 0.05 bar for calculating decompression and oxygen toxicity. e.g. If the setpoint is 1.3, use
1.25 for deco planning and 1.35 for oxygen toxicity planning. This takes into account other factors
that affect the accuracy, such as humidity.
- 49 -
6.14.3
Linearity Check
The oxygen cell output is linear at the oxygen pressures we normally breathe in the rebreather, but
nevertheless it is prudent to check the linearity periodically and especially after a scrubber flood and
clean up. Flush with oxygen, see if the ppO2 reaches the atmospheric pressure and then flush with air
and see if the display reads 0.21 bar. Any variation outside the range 0.19 to 0.23, the cells should be
considered faulty and should be removed for further analysis.
The output of all cells is non-linear above a certain ppO2. After that point you can increase the ppO2
as much as you like but the cell’s mVolt output will not increase. When the cell is new, this occurs at
approx. 4 bar ppO2. As the cell is used the lead anode is consumed and the ppO2 at which the cell
becomes current limited reduces. Once you have one cell that is current limited then it can affect the
oxygen controller. If you have two cells that become current limited below the setpoint (e.g. 1.3 bar)
then they will dominate the oxygen control system causing oxygen to flow into the loop unabated.
The best way to avoid this scenario is to simply insert new cells at 18 months from the date of
manufacture, which is on every cell in a simple coded format (e.g. D9 = April 2009). To check for
non-linearity simple add manually a small amount of oxygen and verify that the ppO2 display goes
above the setpoint. If it does, the output is linear in the operating band.
6.14.4
Checks prior to each use
Prior to diving, press the diluent inflation button. The displayed ppO2 values will drop. Check that all
cells change value quickly (a slow change indicates moisture on the front face of that cell). Once the
ppO2 drops below 0.4 bar the low oxygen warning will display and the warning buzzer sounds.
After a delay of up to 6 seconds, the oxygen solenoid will open and O2 will be injected to bring the
ppO2 back up to and just over the set point of 0.70 bar. Check to ensure that all 3 sensors reach the
0.70 bar set point without any individual cell lagging behind the others.
Manually inject oxygen and ensure that all 3 cells reach atmospheric pressure without any individual
cell lagging the others, have similar values and react at roughly the same speed.
During the pre-breathe sequence ensure the ppO2 values drop as you exhale into the loop and then
ensure all cell values are brought back to setpoint as oxygen is injected.
6.14.5
Verifying the ppO2 during the dive
The computer makes the assumption that the nearest two cells must be correct - it is a simple voting
logic system. However, do not be lulled into thinking the same way as the computer.
For each of the three oxygen cells, the cell’s mVolt output is simply converted to a ppO2 and is
shown in real time. Because the INSPIRATION displays raw data in real time, the reaction time of
the display is instantaneous and this “reaction rate” is a good visual indicator as to the health of the
oxygen cells and electronics.
Remember this:
As the ppO2 in the loop changes - the display for all 3 cells SHOULD change !
Check on every dive to see if all cells are reacting to gas changes.
- 50 -
By forcing changes in ppO2 you can examine the health of the cells at any stage of the dive.
Simply add a little oxygen to bring the ppO2 0.05 to 0.1 bar above the setpoint and then add a
little air/diluent which should lower the ppO2 below the setpoint. This proves whether or not
all three cells are responding to changes in ppO2 and are capable of displaying above and
below the setpoint.
If any cell refuses to display above the setpoint, the dive MUST be aborted and the cell replaced. If
they are all the same age - replace all three.
Additionally the ppO2 values may be checked during the dive by flushing with O2 in the shallows
(less than 6m) or by flushing with air/diluent when deeper. At depth you expect the following ppO2
when you flush with air:
10m - 0.42 bar
20m - 0.63 bar
30m - 0.84 bar
40m - 1.05 bar
50m -1.26 bar.
It is advisable to write the ppO2values for your diluent for every 10m on your decompression slate.
This is used as a rough check to see which sensors are giving proper readings should you ever be in
any doubt regarding the displayed information. It can only be regarded as a rough check because of
the variations between depth gauge readings and different divers’ abilities to do effective gas flushes
but nevertheless it is still an excellent check and at the same time changes the ppO2 in the loop to a
known value.
- 51 -
SECTION 7
DIVE MODE
When first breathing on the INSPIRATION, a rapid drop in ppO2 will be seen. This occurs because
the exhaled breath contains about 17% oxygen. It will take about 3 minutes of breathing to bring the
ppO2 of both the lungs and the breathing loop to a steady state 0.70 bar. Due to the response time of
the cells there may be up to a 6 second delay before the solenoid is actuated to inject oxygen into the
loop. Once at the setpoint the controller will maintain the ppO2 very close to the setpoint. In
independent tests it is proven to be maintained within ± 0.02 bar during the dive. During ascent the
ppO2 will drop due to decreasing ambient pressure but steady state setpoint is achieved at the
mouthpiece within 20 seconds of reaching a decompression stop.
7.1
High/Low ppO2 Setpoint Switch (Master Oxygen Controller only)
By selecting a LOW setpoint (0.70 bar) the diver can descend with less risk of the ppO2 spiking high.
By switching to a HIGH setpoint (1.30 bar) decompression obligations can be minimised.
When in dive mode, pressing and holding the middle button of the MASTER for two seconds will
switch the Setpoint from LOW to HIGH. Releasing and pressing for another two seconds will switch
back to the LOW setting. This 2 second hold time is to help prevent accidental operation during the
dive.
MASTER 0.70
0.71
0.69
0.70
Low setpoint dive mode
(press and hold the centre button for two seconds)
MASTER 1.30
0.71
0.69
0.70
High setpoint dive mode,
when first switching
over.
(oxygen is now injected until the ppO2
reaches 1.30 bar)
MASTER 1.30
1.29
1.30
1.29
(press and hold the centre button
for two seconds)
MASTER 0.70
0.71
0.69
0.70
High setpoint dive mode
(The ppO2 will only reach the
1.3 bar setpoint, providing
you are deeper than 3m.)
Warning:
As mentioned
earlier selecting the HIGH
setpoint when at the surface,
will result in oxygen being
injected to bring the ppO2 in
the loop up to meet the HIGH
setpoint. If the HIGH setpoint
is set above the ambient
pressure the controller will
continue to inject oxygen until
either the LOW setpoint is
selected, the power is switched
off or the INSPIRATION runs
out of oxygen or battery
power! i.e. 1.3 bar in the loop
cannot be achieved until the
apparatus is deeper than 3 m!
Low setpoint dive mode
When surfacing the low setpoint should be
selected between 6m and the surface,
depending on the value of the high setpoint.
- 52 -
7.2
Slave Oxygen Controller
SLAVE 0.70
0.71
0.69
0.70
In Dive mode, the slave, independent of the Master, calculates the ppO2 from its own readings of the
oxygen cells and the master displays the ppO2 in real time.
The slave monitors the master and takes control of the solenoid operation should the Masters
Processor stop e.g. if the Master is switched off or the power to the Master fails.
The white slider buttons on the Slave ONLY activate the backlight and the Slave switch off. The
setpoint cannot be changed using the Slave buttons.
7.3
Backlight
Backlight activation is done by pushing any white slider towards the screen and releasing it. By
pushing the left slider the backlight is activated for 5 seconds. By pushing either the centre slider or
the right slider (NOT BOTH) towards the screen, the backlight is active for 15 seconds.
Use of the backlight reduces the battery life.
The brightness of the backlight can be adjusted to allow for varying climatic and ambient light
conditions. Increasing the brightness reduces the contrast. Alteration of the brightness/contrast
setting has no effect on the battery life.
Turning the brightness up to maximum in some conditions will make it impossible to read the display
due to insufficient contrast between the figures and the background. Turning the brightness down to
minimum in some conditions will result in black squares being displayed making it impossible to read
the figures. A good starting point for UK conditions is to set the brightness between 20 and 40.
The Brightness is an option in the Menu Mode.
You enter the Menu Mode on the Master when the low setpoint is selected and by pushing the left and
right sliders (the outside two) simultaneously towards the screen. See Section 8.
If both Master and Slave are on when you adjust the brightness the new value will not be stored for
future dives. In order to make a permanent adjustment to the brightness, have only one handset
switched on, alter the brightness, leave for 30 seconds, switch off, switch on the other handset and set
the brightness on that one to the desired setting. Leave on for at least 30 seconds and switch it off.
The new values for each handset will then be stored for future use.
If you do use the brightness adjustment underwater, please remember oxygen is not being added when
you are in the Menu mode so the ppO2 is dropping all the time, dropping slowly but still dropping.
Do not spend too long adjusting the brightness, get it done and get out of the Menu mode. The Menu
mode has a time out, if you don’t press a button for 15 seconds you are automatically bounced out to
Dive mode, so please don’t keep pressing one button every 14 seconds. Eventually, you will just go
hypoxic.
Slave - Previously the sliders on the Slave didn’t have any purpose. Now they operate the backlight
for the slave.
- 53 -
SECTION 8
MENU MODE
By using the Menu mode you can alter the high and low setpoints and you can reset the Elapsed ON
Time timer. The default settings are 0.70 bar for the Low setpoint and 1.30 bar for the High setpoint.
Once the Master controller is in dive mode with the LOW setpoint selected, the menu system may be
entered by pressing and holding the left and right buttons simultaneously. This can be done
underwater if necessary but only when the LOW setpoint is selected.
When in menu mode, the controller is not controlling the ppO2 in the loop so there is a time limit on
this operation of 15 seconds from last button press. Exceed 15 seconds and it will automatically
switch to Dive Mode.
(press the outside two buttons
simultaneously)
Important Notes:
1)
The default settings are re-instated every time the
oxygen controller is turned off, so if you change the setpoints
for one dive and require those same setpoints for the next
dive then you will have to change the settings again.
HIGH SETPOINT
Down
1.30
Up
2)
The Slave controller takes the setpoints from the
Master automatically. So, if you change the setpoints on the
Master unit then there is no need to alter the setpoints for the
Slave.
MASTER 0.70
0.69
0.71
0.70
(adjustment range: 0.90
to 1.50 bar)
(Enter by pressing the center
button)
(adjustment range: 0.50
to 0.90 bar)
(adjustment range:
0-99, 30 recommended.
As the brightness
decreases the contrast
increases)
LOW SETPOINT
Down
0.70
Up
3)
The two outside buttons must be pressed at the same
time, within 0.5 seconds of each other. It is the action of
pressing them, not holding them down that activates the
Menu mode. So if you are unsuccessful, ensure you are in
the LOW setpoint mode, release both buttons and press them
both again, simultaneously.
4)
To prevent the unit accidentally entering the Menu
mode whilst underwater, the Menu mode is only accessible
when the controller is in the LOW setpoint dive mode.
BRIGHTNESS
Down
30
Up
5)
The advanced user can change the setpoints
underwater. The unit must be switched to the LOW setpoint.
Whilst in the Menu mode the oxygen controller is not
monitoring the oxygen level and not maintaining the ppO2.
Therefore, there is a time limit of 15 seconds for each phase.
If you have not pressed a button for 15 seconds the display
automatically reverts back to dive mode and automatic
oxygen control.
Elapsed ON Time
2 hrs 23 mins
2.5 secs.
RESET NOW?
Yes
No
Elapsed ON Time
00 hrs 00 mins
0.69
MASTER 0.70
0.70
0.69
DIVE MODE
- 54 -
6)
The timer increases only when the unit is switched
on. The timer does not reset when you switch off the unit. In
this way, the timer shows the total time that the unit has been
switched on since it was last reset by the user. The timer can
only be reset from the menu mode. If the timer is never reset,
the timer will reach a maximum of 255 hours, and stay on
255 hours, and the minutes will reach 59 and then start again
at 00.
When the timer is reset both handsets must be ‘on’ for two
minutes before switching off. The memory is updated only
once per minute, so if the handsets are switched off the timer
will not reset.
SECTION 9
WARNINGS AND REMEDIES
9.1
Low Oxygen Warning
Screen Display –
LOW OXYGEN
0.39 0.38 0.39
BEEP
The LOW OXYGEN warning is activated when the ppO2 drops to 0.4 bar. The buzzer sounds and the
display flashes LOW OXYGEN for one second, flashing back to the dive mode where the setpoint is
displayed for one second, then the buzzer will sound again and the LOW OXYGEN warning will be
displayed. The display will continually alternate until the ppO2 rises above 0.4 bar. In dive mode at
the surface, this can be tested by flushing the loop with diluent forcing the ppO2 below 0.4 bar. The
warning will be displayed and the buzzer activated until the oxygen controller returns the ppO2 to
above 0.4 bar. A
Actions to take when LOW OXYGEN is displayed and buzzer sounds:
Low oxygen can occur for a number of reasons. The most likely cause is that the oxygen cylinder’s
valve is closed. The oxygen contents gauge will register empty if that is the case. Simply opening
the valve may cure the problem. A second possibility is that all the oxygen has been consumed check the pressure gauge. If the pressure gauge shows empty and the cylinder valve is definitely
open, injecting diluent into the loop will rapidly bring the ppO2 up to reasonable levels. It is easy to
flush the loop with diluent by pressing the diluent inflator at the same time as pulling the exhaust
valve’s dump knob.
If there is oxygen in the cylinder but it is not being supplied to the loop by the oxygen controller and
solenoid, the best way to increase the ppO2 is to use the oxygen bypass/inflator located on the exhale
counterlung.
If this situation arises do not panic - there is sufficient time to recover the situation. MOST
IMPORTANTLY you should NOT ascend immediately. During ascent the ppO2 in the loop will drop
extremely quickly. Ascent from 30 m straight to the surface, starting with only 0.4 bar in the loop
would result in unconsciousness before reaching the surface!
9.2
High Oxygen Warning
b Screen Display –
HIGH OXYGEN
1.61 1.65 1.63
BEEP
The HIGH OXYGEN warning is set at 1.6 bar.
Actions to take when the HIGH OXYGEN warning is displayed
Look at the display to assess whether the ppO2 has momentarily spiked because the descent was too
rapid, or if the ppO2 is climbing rapidly. If it is climbing rapidly, close the oxygen cylinder valve and
flush the loop with diluent to reduce the ppO2, by operating the pull cord dump valve and the diluent
inflator simultaneously, then breathe again. Ensure you are pressing the diluent inflator on the left
counterlung and not the oxygen inflator on the right! When reopening the cylinder valve observe the
ppO2. If it climbs rapidly again, it is possible that the solenoid valve is jammed open and the oxygen
cylinder valve must be closed again. Open and close the valve in short bursts to manually control the
- 55 -
ppO2. When deeper than 20m too much O2 may be added using this method unless the diver is well
practised and the alternative of adding diluent to maintain the ppO2 should be considered.
The rebreather may be used in this manner for as long as necessary but open circuit bailout should be
considered.
It is advisable to only open the oxygen cylinder valve by one or two turns. It can then be closed
quickly if required. However, if you breathe from this cylinder via the open circuit 2nd stage at 6 m
and shallower, higher gas flows will be required and the valve will need to be opened more fully.
9.3
“Cell warning”, early versions called this “Cell Error”
A Cell Warning occurs if one cell deviates from the average of the closest two by more than 0.2 bar.
The Cell Warning test is disabled when the solenoid is operating. This keeps the nuisance beeps to a
minimum.
CELL WARNING
1.30 1.29 0.0
BEEP
This display would tell you that there is a faulty connection to cell 3.
This system works fine in the event of you experiencing one faulty cell. But, in the case of having
two faulty cells then it is very important to be able to interpret what the display is telling you.
9.4
Two faulty cells occurring simultaneously, resulting in low oxygen or high
oxygen risks
Low Oxygen Risk
CELL WARNING
1.31 1.00 1.30
BEEP
With a setpoint of 1.30 for example, If two cells are stuck on 1.31 and 1.30, the assumed ppO2 is
1.305 so the solenoid will not open. As you continue to breathe the ppO2 drops and the warning
buzzer will sound when the third cell is 10% adrift. The warning buzzer will sound for 1 second, then
go off for 1 second, then on for 1, then off for 1 for as long as the cell is adrift from the other two.
DO A DILUENT FLUSH. Consider bailout.
- 56 -
High Oxygen Risk
Partial
CELL WARNING
1.65 1.28 1.30
Partial
BEEP
With a setpoint of 1.30 for example, if two cells are stuck on 1.28 and 1.30, the assumed ppO2 is 1.29
so the solenoid will open. As you continue the actual ppO2 will rise and will be indicated by the one
good cell rising in value up to a maximum displayable figure of 2.55 bar, above this the actual ppO2
will depend on the depth you are in (e.g. 5 bar in 40m!).
Remembering that the Cell warning function is inoperative when the solenoid is open, the warning
buzzer will only sound when the solenoid is closed. Knowing the closing and opening sequence of
the solenoid helps here. The controller always closes the solenoid for 6 seconds before making
another decision whether to open the solenoid again, so in this instance it is only in these 6 second
closed periods that a cell warning will be displayed and buzzer activated. The fact that the solenoid is
operating too often and the fact that it is giving you a buoyancy control problem are also good
indicators that all is not well. DO A DILUENT FLUSH. Consider bailout.
9.5
Low Battery
LOW BATTERY
BEEP
Should a Low Battery warning occur on the Master during the dive it is quite in order to manually
switch off the Master unit. This would cause the Slave to become the Master and assume control of
the solenoid and ppO2 in the breathing circuit. If the original Master is switched back on, it will start
up as the Slave and act as a secondary display which requires very little power compared to the
Master which provides the power for the solenoid. You should consider aborting this dive and it is
important to change the battery before the next dive.
The best battery management technique is to simply throw away the Master’s battery when it gets to
the Low Battery Warning. Take the Slave’s battery from it’s slot and insert into the Master’s battery
compartment. Then insert a new battery into the Slave.
This way you always have a relatively fresh battery in the Slave, effectively in reserve. Providing this
technique is adopted it is quite in order just to finish the dive and change the batteries using the above
system prior to the next dive.
9.6
Master Oxygen Controller - Power Failure
BEEP
BEEP
Providing both Master and Slave are in Dive mode - If the
power to the Master fails completely, the Slave display would
automatically take over as Master. This is accompanied by a
double “Beep” as the Slave becomes the Master controller.
- 57 -
9.7
Reset other unit
RESET OTHER UNIT
This is displayed in the Slave display if the Master has failed as a Master but is still switched on and
you turn the Slave off then on again. If this occurs, follow the screen instruction - Reset other unit, by
turning it off then on again. Remember: if you are underwater select “NO” to calibrate.
9.8
Error Assessment
The display alternates every second between the error message and the Dive mode. If more than one
error exists then the display alternates between the errors and the dive mode. For instance, if there is
a cell error and a low battery at the same time the display would alternate as follows:
Master dive mode, Cell Error message, Master Dive mode, Low Battery message, Master Dive mode
etc. When the error is displayed the buzzer is active!
- 58 -
SECTION 10
MAINTENANCE
This must not be undertaken without prior training!
Warning
Do not alter or modify the apparatus in any way without prior written approval
from Ambient Pressure Diving Ltd. Any such action may affect the effectiveness of the
apparatus and may affect the warranty.
10.1 CO2 Absorbent Replacement
The CO2 cartridge is easily refilled by the diver. The normal weight of Sofnolime required is 2.45kg
of 1-2.5mm (8-12 mesh) granule size. Use Sofnolime 797-Diving Grade, preferably “non-colour
indicating”.
The procedure for replacing the Sofnolime is as follows (refer to illustrations on following pages):
a)
Remove the CO2 scrubber canister from the casing. Unscrew the 4 chromed securing nuts
and remove the lid complete with the hoses.
b)
Remove the spacer ring and the O ring.
c)
Using the retaining nut on top of the cartridge pull the cartridge from the canister.
d)
Empty the used Sofnolime into a suitable container for disposal.
e)
Ensure the filter is clean before refilling. Fill the cartridge to about halfway. Whilst filling
tap the canister gently on four sides to aid settling. Continue to fill to within 6 mm of the top
edge.
f)
Place clean/dry filter sheet next to the Sofnolime and replace the pressure spider. Screw
retaining nut on hand tight only. Tap the sides of the cartridge to settle the Sofnolime and
tighten the retaining nut until the pressure spider is flush with the top of the cartridge. Overtightening will crush the Sofnolime.
g)
Before re-inserting the cartridge check to see if the bore of the canister where the O ring will
seal is clean and damage free. Carefully re-insert the canister ensuring that you do not scratch
components.
h)
Inspect the loose, large O ring for damage and ensure it is lightly lubricated. This O ring is
extremely important it prevents CO2 bypassing the Sofnolime. Place the O ring in the
chamfer on top of the cartridge and the large plastic spacer ring on top of the O ring. Ensure
the whole assembly slides easily up and down, if it doesn’t be sure to lubricate the O-ring
- 59 -
i)
Replace the lid of the canister aligning the recess in the lid with the down pipe on the side of
the canister. Fasten the four retaining bolts hand tight so the faces of the lid and the scrubber body
are butted against each other. Over-tightening will result in damage to the body. Under-tightening
will result in the unit leaking.
Warning:
The O ring which fits between the cartridge and the pressure ring, prevents
CO2 in the expired gas from bypassing the Sofnolime. If the bore is scratched, the O ring is
damaged or not lubricated or not replaced after a service, CO2 will be inhaled!
Further Precautions:
WARNING: Do not attempt to partially fill the cartridge. It must be filled completely
otherwise the spring loaded packing system will not function which can result in absorbent
material falling out of the cartridge and most importantly will result in insufficient spring
pressure to hold the cartridge against the large O ring at the top of the cartridge. This would allow
CO2 to bypass the CO2 absorbent.
Do not leave the cartridge open to the atmosphere and expect the Sofnolime to be effective enough
for diving. Instead, seal it up by inserting it back into the canister, reconnecting all the hoses and
breathing bags, and be sure to remember to close the mouthpiece!
WARNING: Under no circumstances should partially used absorbent be emptied from the
scrubber then poured back in later. This will result in premature CO2 breakthrough.
WARNING: Under no circumstances should some of the absorbent be removed and
replaced with fresh material. If you are going to change the absorbent, change it all.
WARNING: Do not leave absorbent open to the atmosphere. The degree of contamination
will be unknown and the absorbent may dry out. Sofnolime when new contains approx. 18%
water which is essential in the CO2 absorption chemistry.
Sofnolime is alkaline so appropriate safety measures should be implemented. Protective gloves,
goggles, overalls and nuisance dust masks should be worn when handling Sofnolime granules
irrespective of whether they are in a fresh or used state.
The granules or any entrained dust should not be allowed to come into prolonged contact with the
skin and contact with the mucous membranes and the eyes must be totally avoided.
Residual or waste Sofnolime will contain some residual alkalinity but can normally be disposed of at
a suitable landfill site.
Granules will bleach boat decks, so avoid spilling and be sure to clean up afterwards.
Always inspect the cartridge prior to diving.
- 60 -
Removing the CO2 Scrubber and Sofnolime Cartridge
Unscrew the scrubber
hose fittings at the Tpiece
Unscrew the lid
securing nuts.
Remove lid by
pulling upwards
Remove spacer
Squash the hoses
to remove them
from the casing
Remove large
O ring
!
Warning:Handle With
Care & keep
safe
Remove the
cartridge
Remove scrubber,
hoses and electronic
units from the casing
Turn the cartridge
over and unscrew
the retaining nut
Remove the spring/
pressure plate
assembly
- 61 -
Refilling the Sofnolime Cartridge
Ensure the filter scrim is
clean and undamaged. Push
it into the cartridge as far as it
will go
The filter scrim must be
located properly in the bottom
with no gaps around the
edges or the centre column.
Its purpose is to retain the
Sofnolime granules and keep
water out
Ensure there is a 6mm
gap at the top
Ensure the scrim is clean
and undamaged
Store Sofnolime in the
manufacturers sealed
containers, following their
storage instructions
Fit the spring loaded
pressure spider
Fill to approximately half
way and tap gently on the
sides to level the granules
Fasten the centre hand
wheel
Do not over-tighten
Fill to within 6mm of the top
and tap gently on the sides to
level the granules
- 62 -
Mistakes to avoid when filling the sofnolime cartridge
Do not overfill.
Over-filling combined with over-tightening
makes the sides of the cartridge bulge and
prevent the springs from pushing the
cartridge against the O ring
Do not under-fill, this allows CO2 to by-pass
the whole cartridge as pressure is no longer
applied to the O ring
Do not over-tighten
If you over-tighten it the top may distort
and may come adrift from the parallel
sides. If this happens return to the factory
for repair
- 63 -
Re-fitting the Cartridge and Complete Scrubber Assembly
After inspecting the bore
for damage or dirt - Insert
the cartridge carefully
taking care not to scratch
any components
Ensure the O ring seal
on the canister lid is
undamaged, clean and
properly located
Slide the canister lid
on carefully
Push down and ensure the
cartridge is free to move up
and down and check for the
spring loading effect of the
pressure spider
Fasten the four screws
gently and evenly until
the mating surfaces join.
Do not use excessive
force at any time
Ensure this O ring is
undamaged, clean, lightly
lubricated and properly
located
Check the top of the
cartridge for dirt or damage
and place O ring on top,
inserting it into the
chamfered groove around
the top of the cartridge
Ensure the spacer ring is
clean and undamaged
and place carefully onto
the O ring
- 64 -
When re-inserting the
scrubber assembly ensure
the Velcro band passes
between the scrubber wall
and the down pipe
The scrubber locates on
the back frame and is
held in place by the
Velcro band. The inlet
pipe MUST sit
underneath the cylinder
against the backframe.
Squash the convoluted
hoses to insert them into
the back frame, ensuring
they spring back into shape
and do not impede the gas
flow.
Ensure the breathing
hoses are not kinked
where they pass
through the back
casing
Re-fasten the hoses. Nip
them up hand tight.
Excessive force does not
improve the sealing effect
10.2 Gas Cylinders
The two gas cylinders are each secured to the carrying frame by a single band in the centre of the
cylinder. When securing the cylinders into the carrying frame - pass the band through just one of the
slots in the buckle, tighten the band and fasten the Velcro.
Do not use cylinder mesh or other protective cover on the cylinders. The band and rubber anti-slip
pads must be in contact with the painted cylinder surface to function properly.
The oxygen cylinder is located on the right hand side of the user and the diluent on the left. The
diluent cylinder will be on the same side as the buoyancy compensator’s inflator. Both cylinders are
marked according to their contents.
From new, the oxygen cylinder and oxygen components, such as the first stage, hoses, contents
gauge and inflator, are oxygen clean and compatible.
Warning
It is recommended that the condition of the cylinder is assessed at 6 monthly
intervals. In particular, if the oxygen cylinder is contaminated with salt water then it must be
cleaned without delay otherwise corrosion will rapidly occur in an oxygen rich environment.
The diluent cylinder, first stage and components, however, are NOT oxygen clean as the diluent used
is normally compressed air. If it is intended that this rebreather is to be used with a Trimix or Heliox
diluent and the fill method is by partial pressure blending, then it will be necessary to oxygen clean
both the cylinder and cylinder valve.
Contact Ambient Pressure Diving, as some of the valve components and the lubricant must be
replaced.
- 65 -
10.3 First Stages
After closing the cylinder
valve and purging the hoses,
unscrew the DIN handwheel.
If this is difficult, ensure all
the pressure is released from
the system. In time you will
need to re-lubricate this
connection - only use an
oxygen compatible grease.
DO NOT USE SILICONE
GREASE OR OIL.
Both the oxygen and diluent cylinders use a first stage pressure reducer. Both are marked
accordingly and must not become mixed up. i.e. do not use the oxygen 1st stage on the air cylinder
and vice versa. The oxygen 1st stage has been specially prepared using oxygen compatible O rings
and lubricants - the diluent cylinder has not. It is only prepared for use with Normoxic gas (21%
oxygen). The practice of relying on the diver inserting the correct valve into the correct cylinder is
common in the technical diving communities on both sides of the Atlantic, the DIN thread being the
preferred connection. The responsibility for connecting the 1st stages to the correct cylinders is the
responsibility of the diver - YOU.
Both are adjustable diaphragm types but the following set up pressures must be adhered to when
servicing:
Oxygen 1st Stage
- Interstage Pressure:
Diluent 1st Stage
- Interstage Pressure:
7.5 bar. Under no circumstances must the interstage pressure be
increased above 8.0 bar! The interstage pressure should be adjusted
with only 50 bar in the cylinder.
9.2 to 9.5 bar. The interstage pressure of the diluent cylinder may
be altered to suit the open circuit 2nd stage fitted - maximum pressure 13 bar.
10.4 LP Oxygen Hose
Connect the low pressure (8 bar) oxygen hose to the solenoid valve in
the top of the scrubber. Finger tighten using the knurled ring. DO
NOT USE A WRENCH - It is extremely common for divers to use
far too much force. Over-tightening does not improve the seal, it
simply risks damaging other components.
- 66 -
10.5 Post-Dive Maintenance
The breathing bags and mouthpiece should not be completely stripped down after every use. You are
more likely to create problems for yourself.
10.5.1 Cleaning and Disinfecting the Unit
We advise users to disinfect their rebreather after each day of use. Only in this way can its
cleanliness be ensured. However, disinfecting involves some disassembly and if not carried out with
care, leaks may be introduced into the system during re-assembly. It is important that leaks are
rectified if the reliability and integrity of the system is to be restored. If the rebreather is shared with
another diver the system should be thoroughly disinfected before use.
After each dive the mouthpiece should be rinsed in fresh water, taking care not to allow large
quantities of water to enter the loop. Providing the rebreather is standing upright, all the water will
enter the exhale counterlung and this is easily drained. Take care not to allow too much to enter
while the scrubber hoses are still connected.
At the end of each day’s diving remove the hose and the mouthpiece as an assembly, rinse in a
disinfectant solution such as BUDDY Clean and rinse thoroughly in warm fresh water.
Warning
Do not use solutions of Milton or other baby bottle sterilising solutions.
These discolour and rot the inner and outer bags.
After every 6 hours total diving, disinfect the mouthpiece, hoses, counterlungs and inside the
canister. Inspect the counterlungs for foreign matter. The outer bag of each counterlung has a zip to
aid inspection of the inner. Do not leave components soaking in cleaning solution for more than 30
minutes.
10.5.2 BUDDY Clean Disinfectant
BUDDY Clean Disinfectant has been specially formulated for its ability to destroy a wide variety of
bacteria, viruses and fungi including Legionella, Weil's disease, Tuberculosis, HIV and also for its
very low hazard risk. See Appendix 5. BUDDY Clean is not FDA approved for use in America;
Silent Diving Systems LLC (www.silentdiving.com) should be consulted for approved disinfectant in
the USA.
10.5.3 Lubrication
It is essential when lubricating seals or O rings on the rebreather and oxygen valves, that an oxygen
compatible grease is used. Recommended greases include Fomblin RT15, Halocarbon 25-5S grease
and Oxygenoex FF250.
- 67 -
10.5.4 Washing and Disinfecting the Breathing Circuit with BUDDY Clean
Unscrew the rear
most hoses from
both T-pieces
Spray or pour
BUDDY Clean
disinfectant into
the T-piece
Repeat the process,
thoroughly
flushing the
counterlungs with
fresh water
Remove the hoses
and spray or pour
disinfectant
into
the inhalation hose
With the
mouthpiece closed,
use a clean hose to
fill both
counterlungs with
warm, fresh water
Use a clean hose to
flush through with
warm, fresh water
Unscrew the
inflators, taking
care not to lose the
O rings
Spray the
mouthpiece with
disinfectant and
thoroughly flush
through.
Do this with the
mouthpiece open
and closed to wash
the water drain
Always check the non-return valves for proper
operation after washing. (see Section 4.3)
- 68 -
10.5.5 Oxygen Sensors
If, after the dive, water is suspected to have entered the scrubber then the unit must NOT be stored
horizontally. To do so will result in the oxygen cells and the battery compartment becoming soaked.
Should this occur the cell face should be washed in warm fresh water, the batteries removed, any
residue removed and the lid air dried.
10.5.6 Exchanging Oxygen Sensors
Oxygen sensors are a consumable item and should be replaced regularly. The life of a sensor varies
with the temperature and the ppO2 it is exposed to; assuming they don’t fail due to vibration, shock,
fast pressure changes or external force. The higher the temperature or the higher the ppO2 the
oxygen cell is stored at, the shorter the life of the cell. Simply leaving the oxygen cells in the lid at a
temperature between 5oC and 25oC in AIR is sufficient to aid a reasonably long life. Typically in the
rebreather application, oxygen cells should be replaced when they are between 12 and 18 months old.
Beyond this period the diver should pay particular attention to the linearity checks above the working
setpoint. i.e. ensure the displays will reach 1.4 bar when the setpoint is 1.3 bar.
To replace the oxygen cells it is necessary to remove
the scrubber from the rebreather, remove the outlet
hose from the lid and remove the cell holder/battery
box assembly from the scrubber lid.
Remove the blue indicator ring.
WARNING: (Be sure to re-fit the blue indicator ring
afterwards; it’s not just there as a hose connection
colour guide, it also acts as a slip ring between the
hose nut and the cell holder retaining nut and
essentially helps prevent the two nuts locking
together when you tighten the hose fitting. If this is
not in place there is a risk of you unscrewing the
sensor holder from the lid when you routinely
remove the hose.)
Use the special tool (AP203) which is supplied with
each rebreather to unscrew (anti-clockwise) the cell
holder retaining nut.
- 69 -
Once the retaining nut is removed gently pull the cell
holder assembly from the lid.
WARNING: Do not attempt to unscrew the oxygen cells
without disconnecting the wires.
WARNING: Do not pull on the wires
Pull the red cover off the back of the cell, sliding it
back up the wire.
Pull out the black locking device, leaving the
connector still attached.
Hold the locking leaf moulding away from the white
connector body and gently pull on the white body, NOT
on the wires.
Once disconnected the oxygen cell is free to unscrew and be replaced. Sometimes the oxygen cells
are supplied with an O ring on the M16 thread – this is not required and could be removed. The
original oxygen cells were installed with a blue or white extension tube fitted to the front face. These
components are no longer required with the new cells and should be discarded.
WARNING: Only oxygen cells supplied by Ambient Pressure Diving should be used. Most
oxygen cell manufacturers think they manufacture a replacement for the ones used in the
INSPIRATION but no oxygen cell manufacturers have a complete understanding of the
requirements for oxygen cells in the INSPIRATION, whether it be environmental conditions,
methods of use or the static and dynamic requirements of the INSPIRATION electronics and it is
only with extra quality assurance performed at Ambient Pressure can the oxygen cells be determined
as “fit for purpose”. Several accidents have occurred due to the diver fitting non-Ambient Pressure
Diving supplied oxygen cells.
WARNING: DO NOT USE a mix of RB06/01/07 and APD6 oxygen sensors together. You
must use 3 of APD6 or 3 of RB06/01/07, not a mixture of the two types.
- 70 -
Re-assembly:
1) Carefully screw the replacement oxygen cell into the holder, taking care not to cross the thread.
2) Inspect the gold pins in the white Molex connector looking for poor connection to the wires,
discoloration of wires or pins, or misshapen pins. Only the outside two pins are used for cell voltage
measurement. Gently tug on the wires and ensure the pins are held securely in the white connector
body. If in doubt have new pins and connectors fitted. Contact the factory for details.
3) Re-attach the white Molex connector ensuring the small white lugs are around the retaining leaf.
WARNING: ALWAYS screw the oxygen cell holder into the holder prior to attaching the
white Molex connector.
4) Slide the black locking device into place using the minimum force. It is designed to only fit in one
way and when correctly positioned, the white Molex connector should stand perpendicular to the
back of the cell. If it is leaning over excess strain is be exerted on the cell’s pins and this may result
in intermittent connection!
5) Push the red cover gently back onto the oxygen cells taking care not to put strain on the wires and
their connections to the gold pins.
6) Inspect the O ring in the inside of the lid, checking for dirt or damage and replace if necessary.
Lubricate lightly with silicone grease or oxygen compatible grease.
7) Insert the holder back into the scrubber lid ensuring none of the cables are trapped between the cell
holder and the inside of the scrubber lid.
8) Line up the flat on the cell holder with the flat in the centre hole of the scrubber lid and whilst
holding the fitting firmly and squarely against the inside of the lid, replace the retaining nut – always
maintaining constant pressure to hold the cell holder against the inside of the lid.
WARNING: Ensure the two flats stay in line. If the cell holder is allowed to twist round, it
will be impossible to make this seal waterproof.
9) Tighten the cell holder retaining nut with the special tool and replace the blue indicator ring
pushing it down to the lowest visible thread.
WARNING: do a positive and a negative pressure test and check for leaks prior to diving.
10.6 Storage
The INSPIRATION should be stored upright or lying on its counterlungs. If you lay the rebreather
on its back at the end of the dive then you risk water running onto the face of the no. 2 oxygen cell.
This may result in a cell failure when you next switch the unit on and the oxygen controller will not
enter dive mode - preventing you entering the water. Cell 2 should then be removed and allowed to
dry naturally before use. Repeated or excessive soaking will reduce the life of the cell.
The oxygen cells can be stored down to -20oC without consequence, unless freezing and thawing
cycles are repeated, in which case the electrolyte seals may be damaged with the possibility of
leakage of the electrolyte. Intermittent exposure to temperatures of 45oC are acceptable, though
continuous exposure to high temperatures will shorten cell life.
- 71 -
After cleaning, store the apparatus upright, out of direct sunlight, with the BC and counterlungs
partially inflated, in a cool, (5-15oC), dry and dust free place. Avoid exposure to direct ultra-violet
radiation and radiant heat.
10.7 Precautions when using High Pressure Oxygen
Warning: Open cylinder valves slowly.
Use only oxygen clean components and oxygen compatible materials.
Ensure there is no oil or grease contamination.
See Section 10.5.3 for suitable lubricants.
10.8 Service Intervals
Maintenance is an ongoing task with all rebreathers and users must check for proper operation before
every dive. Additionally some components must be serviced at periodic intervals:
Diluent Cylinders:
As supplied from the factory these are prepared ready for normal quality diving air and as such are
NOT specially oxygen cleaned. The same applies to the cylinder valve. The inspection and
hydrostatic testing regulations for this cylinder will vary from Country to Country. In the UK, the
current requirements are for internal inspections every 2½ years with a hydrostatic test every 5 years.
Oxygen Cylinders:
Supplied from the factory, these cylinders are oxygen clean. The legal requirement in the UK is for an
internal inspection every 2½ years with hydrostatic testing every 5 years. Oxygen cylinders must be
serviced and oxygen cleaned every year.
1st stages:
The 1st stages should be dive shop serviced on an annual basis.
Auto Air:
The Auto Air should be dive shop serviced annually.
Oxygen Cells:
The life of the oxygen cells will vary from cell to cell and user to user. Between dives the loop
should be flushed with air. Leaving the cells in a high oxygen % shortens the life of the cells
dramatically. The cells should be replaced every 12-18 months. They should be replaced
immediately if signs of deterioration are present, regardless of age. Under no circumstances should
you use the oxygen cells beyond 18 months from date of manufacture. Oxygen cells constantly
deteriorate and have a finite life, even in the sealed packaging. If you hold a spare oxygen cell this
should be discarded 18 months from the date of manufacture even if unused. Oxygen cells would be
depleted in a matter of weeks if stored in an oxygen rich environment.
- 72 -
SECTION 11
EMERGENCY PROCEDURES
11.1 Bail-Out (Emergency Breathing)
Never dive without sufficient open circuit bail out
During a dive, very little diluent gas should be used. Typically only about 30 or 40 bar will be
consumed from the 3 litre cylinder. The diluent cylinder provides gas for counterlung volume during
the descent, for lung volume adjustments throughout the dive, for BC inflation and for dry suit
inflation. (If a Heliox diluent is used it is recommended that a separate cylinder is carried for suit
inflation). Because so little diluent is used, the diluent cylinder may provide sufficient gas for
bailout. To take advantage of this an Auto Air is fitted to the BC. The Auto Air is also an
overpressure relief valve should the 1st stage HP seat leak. If the Auto Air is removed it must be
replaced with a suitable open circuit breathing system and suitable overpressure valve. For
emergency breathing at 6 m and shallower, an oxygen clean 2nd stage can be used to breathe from the
3 litre oxygen cylinder. However, an isolator should be fitted in the line so that the oxygen supply to
this 2nd stage is normally switched off to prevent accidental gas leakage from this 2nd stage and also to
help prevent your diving partner from accidentally using this mouthpiece at depths greater than 6 m.
For extreme air dives and mixed gas dives the volume and type of bail out gases must be reassessed.
For instance, you may decide to carry a 5 litre cylinder containing Bottom mix or 40% Nitrox or it
may be best to carry two 7 litre cylinders hip or back mounted, one with Bottom mix and one with
80% or, depending on the dive scenario, it may be better to place bailout gas on the shot line. The
bailout is just as much a limiting factor to your dive planning as the gas mix selected. Ensure you
have sufficient volume of breathable, open circuit gas available at all stages of the dive.
11.2 Emergency Procedures
What do you do in the event of a Low oxygen warning?
What do you do in the event of a High oxygen warning?
If in Doubt –
What do you do in the event of a battery warning?
What do you do in the event of a battery failure?
What do you do in the event of a flooded loop?
What do you do in the event of a cell warning/cell error?
- 73 -
Flush with diluent
and considering
switching to open
circuit bailout.
11.3 Diluent Flush
This very simple procedure is the cure, albeit temporary in some cases, for
most of the above problems. If the O2 level is too low then flushing with
diluent will raise the ppO2 to a breathable level. If the ppO2 level is too
high, flushing with diluent will dilute the oxygen. If there is water on the cell
face the diluent flush will aid evaporation. To perform a diluent flush press
the diluent inflator, for approximately 10-15 seconds, whilst holding open the
exhaust valve.
11.4 Emergency Rescue of an Unconscious INSPIRATION Diver
DO NOT remove the mouthpiece. Flushing the system with diluent may assist in the recovery of
consciousness. A skilled and experienced INSPIRATION user should be able to assess a buddy’s
system to identify a problem and effect a cure eg. opening the O2 cylinder valve. If no probable
cause can be identified then an assisted ascent may be carried out, regularly flushing the buddy’s
system to ensure a respirable mix is present in the loop.
11.5 Flooded Loop
The INSPIRATION is very tolerant of water entry. The action to take largely depends on the
circumstances leading up to this problem and how much water has entered.
If you have just dropped the mouthpiece without closing it and then re-inserted it, you will allow
water into the exhale counterlung. Providing you stay reasonably upright you should be able to
continue the dive, leaving the water in there. If you continue to do head down descents or
somersaults, then water in the counterlung will find its way past the water trap and go into the bottom
of the scrubber. This is noticeable by a more distant gurgling noise which becomes worse when you
roll onto your right side. Depending on the quantity of water which has entered, this is not too
serious a problem. You should, though, empty the water out at the end of the dive, dry the scrubber
and change the Sofnolime.
There is a water barrier at the bottom of the Sofnolime cartridge, but eventually water will permeate
around the edge of this and be soaked up by the Sofnolime granules. Because of the water traps at
the top of the scrubber and on the top of the inhale counterlung, there is virtually no chance of getting
a “caustic cocktail”. However, if you do soak the Sofnolime excessively a faint chalky flavour may
be noticed in the inspired gas. If this flavour becomes evident in conjunction with the gurgling when
you are on your right side with an increase in breathing resistance, then the dive should be aborted,
the system dried and Sofnolime changed.
Excessive amounts of water can be vented by rotating so the overpressure valve is downwards and
pressurising the loop so the excess water is forced out. This requires practice and usually allows
water into the bottom of the scrubber. Pressurising the loop causes excess buoyancy and so the diver
must fin downwards or hold onto something substantial.
If you receive water down the inhale hose, then this is most likely to be due to residual water in the
counterlung remaining there after washing. Rotating into a head up position should enable normal
breathing to commence.
If in doubt - bail out!
- 74 -
11.6 Manual Control of ppO2
The ppO2 can be held within the life support range by adding either O2 or diluent. The gas may be
supplied by on-board or off-board cylinders connected to the manual inflators on the counterlungs.
11.6.1 Manual addition of O2 and O2 flush method
Providing the ppO2 displays are functioning and are monitored the ppO2 can be maintained easily, by
manually adding O2 in short bursts.
With practice it is possible to maintain a constant ppO2 without looking at the displays, but this
involves timing the interval between oxygen injects or counting the number of breaths. However,
this technique requires considerable practise and is only valid when the depth stays constant. This
technique is deemed too dangerous.
To do a fast oxygen flush (at 6m or shallower), press the oxygen inflator for several seconds and
purge gas from around the mouthpiece at the same time. Take a few breaths, then repeat flush. This
is a very quick method and is easily done without affecting buoyancy.
11.6.2 Manual addition of diluent
Providing the ppO2 displays are functioning and are monitored the ppO2 can be maintained easily, by
manually adding diluent in short bursts. Because you are adding inert gas to the loop, as well as
oxygen, gas should be vented from the loop to maintain neutral buoyancy.
Maintaining a life sustaining ppO2 is easy when adding diluent, even without a ppO2 display. It needs
practise to make it efficient but it is a simple procedure. Practise , whilst monitoring the ppO2
display, in a shallow swimming pool using an air diluent, start by exhaling through your nose every
third breath and then adding air to allow you to breathe from the counterlungs. Some divers may
find, by practising while watching their ppO2 displays that they can exhale less often but please bear
in mind the following warning:
Warning
It is important to find the number of breaths between exhales when in the
shallows and when working moderately hard and then use this at all depths. Do not
experiment at depth and then apply your technique in the shallows. If you are using the
INSPIRATION in this semi-closed fashion as a bail-out, it is important that the oxygen content of the
diluent will sustain life in this semi-closed manner all the way to the surface. Beware of trying to use
a diluent with only 15% or less O2 content.
- 75 -
11.6.3 Using the INSPIRATION as a pure oxygen rebreather
It is easy to maintain a high oxygen content manually by monitoring the ppO2 displays but if the
display is switched off or not functioning then at depths of 6m and shallower it is possible to use the
INSPIRATION as a pure oxygen rebreather. The technique is to flush out all the Nitrogen so there is
only pure oxygen in the breathing loop, which includes the diver’s lungs, and then add oxygen
manually as the counterlung volume diminishes.
Warning
This technique is potentially very dangerous and must not be attempted
without proper training and practise whilst monitoring the ppO2 displays. Complete oxygen
flushing of the loop must be done thoroughly. If Nitrogen is present in the loop then there is
a great risk of the diver going unconscious through hypoxia. Most Navies have accidents every year
because the diver doesn’t do an adequate oxygen flush when using a pure oxygen rebreather.
Particular attention must be paid to the oxygen flush technique.
When 5 m or shallower select a low setpoint (0.7 bar), exhale through nose until counterlung volume
diminishes - preventing the next inhale, add oxygen to counterlungs to allow next inhale. Breathe for
a few breaths, and then repeat the process again three times. After that add oxygen when the
counterlung volume diminishes enough to make breathing slightly difficult. Then add just enough
oxygen to allow breathing. While you do this monitor the ppO2 displays. After practise you should
be able to maintain a pretty constant ppO2.
- 76 -
SECTION 12
BRIEFING OPEN CIRCUIT DIVE PARTNERS
12.1 The Rebreather Diver – What to Expect, What to Do
(Author: Stephen Bird)
BASICS
Closed Circuit (CC) Rebreather diving has a number of differences from Open Circuit (OC), but also
a number of similarities.
ON THE SURFACE - In any problem scenario once back on the surface the CC diver should be
treated exactly the same as an OC diver. This includes all DCS occurrences, respiratory problems
and any other diving related ailments. Use of CC does not preclude the use of Hyperbaric treatment.
UNDER THE WATER – The CC diver will do things slightly differently to the OC diver. Things
you will notice, that are quite normal are:
·
·
·
·
Buoyancy – The CC diver will swim around objects rather than over them
Computer Checks – The CC diver will check the computers at 30-second intervals, this is
essential in monitoring the well being of the equipment.
Bubbles – There are usually none. Exceptions are mask clearing, upward buoyancy adjustments
and always on ascents.
Busy – On descent and ascent the CC diver will look busy; these are times of high task loading,
once at working depth only the computer checks may be evident.
PRE-DIVE CHECKS – For the CC diver the usual buddy checks for buoyancy, air and releases is
the same as OC, except that one source of gas (the closed circuit one) is checked as part of a unique
CC check routine. This routine involves a complete, part computer guided, systems check the final
part of which is a 3-minute breath test.
DIVE MARSHALL LOG – Again essentially the same as an OC diver, but gas consumption will be
about 1 litre / minute from the Oxygen cylinder and negligible from the Diluent cylinder which is
used mainly for buoyancy and OC back up (bailout). So the extra information to be recorded is O2
contents, diluent contents, scrubber duration and PO2 setpoint.
THINGS AN OC BUDDY SHOULD KNOW – How to open and close the CC mouthpiece, the
operation of the diluent and O2 manual inject valves, (but normally leave the latter well alone), and
recognise the terms and symptoms of hypoxia, hyperoxia and hypercapnia. This is within the skillset of BSAC Sport Diver and above, but would possibly not be appropriate for anything less than a
PADI Rescue Diver.
- 77 -
12.2 Classic Problems, Causes and Resolutions
The following table lists classic problems, the probable cause, the CC divers resolution and if
required the buddy divers assisting action. It should be noted that nearly all problems could be
resolved by a capable CC diver without switching to OC bailout, but that option always exists. For a
rescuing buddy nearly all problems can be resolved with a diluent flush, but again the option to assist
with OC bailout using on-board gas or his own OC octopus exists. The general rule is:
IF IN DOUBT, BAIL OUT.U
PROBLEM
CAUSES
CC DIVER
RESOLUTION
OC BUDDY RESOLUTION
Fast ascent
Add O2 manually or
diluent flush, slow the
ascent.
Diluent flush or offer bailout /
octopus, then diluent inject every
third breath, then rescue to the
surface.
Diluent flush or offer bailout/
octopus, check O2 cylinder valve is
on, then rescue to the surface.
Diluent flush or offer bailout /
octopus, then diluent inject every
third breath, then rescue to surface.
Diluent flush, slow the ascent,
offer bailout / octopus, then diluent
inject every third breath, then
rescue to surface.
Solenoid jammed
open
Diluent flush and
switch O2 cylinder
valve off, use valve to
control injection of O2
Diluent flush and switch O2
cylinder valve off, offer bailout /
octopus, then diluent inject every
third breath, then rescue to surface.
Accidental O2
manual injection
Fast descent
Diluent flush
Diluent flush, offer bailout /
octopus, then rescue to the surface.
Diluent flush, offer bailout /
octopus, then rescue to surface.
Full Electronics
failure
Water ingress,
batteries flat,
broken something
etc
Use diluent flush, then
go to diluent based
semi closed mode
Diluent flush or offer bailout /
octopus, then diluent inject every
third breath, then rescue to the
surface.
Scrubber flood
and caustic
cocktail
Leakage of water
into scrubber
housing
Switch to OC bailout
Offer bailout / octopus, then rescue
to surface.
Low Oxygen
Solenoid Blocked
Use O2 manual inject
O2 cylinder valve
switched off
Switch back on
O2 cylinder empty Use diluent flush, then
or no access to O2 go to diluent based
at all
semi closed mode
High Oxygen
Diluent flush and slow
the descent
- 78 -
SECTION 13
WARRANTY
The INSPIRATION is warranted for the first purchaser for 12 months from date of purchase.
Conditions:
All warranty work must be authorised by Ambient Pressure Diving Ltd. Before returning the
apparatus for any reason, please telephone the factory for advice. If it is deemed a factory repair is
required the apparatus should be returned, postage and insurance paid, with a copy of the purchase
receipt, directly to the factory, NOT TO THE DIVE SHOP.
1)
Misuse, neglect or alteration renders all warranties null and void.
2)
This warranty is not transferable.
Your statutory rights are unaffected.
Exclusions:
1)
The batteries are not covered by the warranty.
2)
The oxygen sensors are not covered by the warranty, they will need to be replaced
every 12-18 months or sooner depending on the ppO2 they are stored in.
3)
The counterlung outer bag colours, even the black, will fade in time - especially if
subjected to strong sunlight
4)
The counterlung’s inner bags are not covered against punctures.
5)
If a strong sterilising fluid is used then the inner bags may deteriorate.
Applicable Law:
All products are sold only on the understanding that only English Law applies in any and all legal
claims against the manufacturer, regardless of where the equipment is purchased or where used.
Should a claim be made the venue for this will be Truro, England. If this clause is not acceptable to
you or your family then return the product unused to your place of purchase for a refund.
Warning: It is dangerous for untrained and uncertified persons to use the equipment covered
by this warranty. Therefore, use of this equipment by an untrained person renders any and all
warranties null and void.
- 79 -
SECTION 14
IMPORTANT CAUTIONARY NOTES
DO:
Know your ppO2 at all times!
DO:
Read the instruction manual fully before using the INSPIRATION.
DO:
Carry out the pre-dive checks prior to each dive.
DO:
Use diving quality gasses.
DO:
Post-dive maintenance, particularly cleaning and disinfecting the breathing loop.
DO:
Have your INSPIRATION serviced annually by a competent person.
DO:
Insure all your dive equipment.
DO:
Keep a record of the usage of the apparatus, particularly the Sofnolime, batteries and oxygen
cells.
DO:
Ensure that only original parts are used in the repair of the INSPIRATION.
DO:
Practice in a pool to increase familiarity with the operation and adjustments of the apparatus.
DO:
Handle the Sofnolime safely and store it in a dry, airtight container.
DO:
Only use the correct batteries and dispose of them immediately they are finished.
DO:
Take spare oxygen cells and batteries when travelling.
DO:
Connect blue to blue when reconnecting breathing hoses.
DO NOT:
DO NOT:
DO NOT:
DO NOT:
DO NOT:
DO NOT:
DO NOT:
DO NOT:
DO NOT:
DO NOT:
DO NOT:
DO NOT:
DO NOT:
DO NOT:
DO NOT:
breathe from the loop without switching on electronics and checking ppO2
ignore warnings
ascend too rapidly.
descend too rapidly. The ppO2 may increase to dangerous levels.
mix up the diluent and oxygen fittings.
use silicone grease or oil on the system. Use only oxygen compatible grease.
reuse Sofnolime.
partially refill the cartridge with Sofnolime.
try to prolong the life of the oxygen cells by storing in a sealed bag or in an inert gas.
recharge the batteries.
switch off both oxygen controllers whilst submerged.
calibrate the unit whilst submerged.
fill the oxygen cylinder with Nitrox.
fill the diluent cylinder with pure gasses such as Helium or Nitrogen.
disconnect the Auto Air hose if the Auto Air leaks air, close the cylinder valve and
check the Interstage pressure.
- 80 -
SECTION 15
TECHNICAL DATA
Atmospheric Range:
Battery (6v Lithium):
700 - 1050 mbar
The preferred brand is Fujitsu Lithium 6 volt, type CRP2. In
use this battery has proven to have a greater capacity than other
brands, giving proper solenoid operation within the voltage
warnings provided by the electronics and for longer life.
Buoyancy Compensator:
CO2 scrubber:
Wing style in 16kg and 22.5kg sizes.
2.45kg of 797 grade Sofnolime
Micro-filters prevent dust from entering the breathing hoses.
Water-traps virtually eliminate the possibility of a “caustic
cocktail”.
Medium - 11.4 litres (5.7 litres per counterlung)
Large - 14 litres (7 litres per counterlung)
Counterlung Volume:
Cylinders:
Two 3-litre steel cylinders, one oxygen, one diluent. (M25 x2
cylinder thread, ¾”NPSM – USA)
Depth Limits:
40m
100m
100m
110m
150m
160m
max. Depth with air diluent.
max. Depth at which all rebreather parameters are proven: CO2 endurance, O2
control and work of breathing.
the limit of the CE approval.
max. Depth at which the work of breathing has been tested using Trimix
diluent.
max. Depth at which the work of breathing has been tested with an Heliox
diluent.
Depth at which all components are pressure tested during type approval – not
during production.
WARNING: Diving deeper than 100m carries the following additional risks:
Deeper than 100m:
Deeper than 110m:
Deeper than 150m:
Deeper than 160m:
Design:
Dimensions:
Display accuracy:
Display resolution:
First stage (Oxygen):
First stage (Diluent):
Harness:
CO2 endurance unknown.
Work of breathing with a Trimix diluent unknown.
Work of breathing with an Heliox diluent unknown.
Structural integrity of components unknown – the air cavity within the buzzer
will implode eventually, and other components may fail.
Rear mounted, with over-the-shoulder twin counterlungs
650mm (H) x 450mm (W) x 230mm depth (excluding
harness/counterlungs and BC)
650mm (H) x 450mm (W) x 350mm approx. depth (incl.
harness, c/lungs and BC)
± 5%
0.01 bar
Intermediate Pressure - 7.5 to 8.0 bar
Intermediate Pressure - 9.0 to 9.5 bar
Multi-adjustable harness in 4 sizes, Small, Medium, Large and
X-Large.
- 81 -
Hydrostatic Imbalance:
<1.0 kPa (10mbar) in all rotations.
Oxygen Control:
Two oxygen pressure setpoints, switchable from low to high
and high to low as often as required, both underwater and on
the surface.
Oxygen sensors:
3 Galvanic cells, Product Code:
RB06/01/07 (Teledyne R22-2BUD), (Pre October 2010)
or
APD6 (post October 2020)
Oxygen setpoint range (Low):
Oxygen setpoint range (High):
Oxygen warning level (Low):
Oxygen warning level (High):
0.5 to 0.9 bar
0.9 to 1.5 bar
0.4 bar
1.6 bar
Rebreather Operating Temperature Range:
+4oC to + 32oC
Short term air storage (hours): -10oC to +50oC
Long term storage:
+5oC to +20oC
The rebreather operating temperature range is determined at the cold end by the CO2 duration trials
which are done at 4oC(1). Below this temperature the duration of the CO2 absorbent has not been
empirically determined. If stored below 0oC the CO2 absorbent and electronics will need gentle preheating prior to use by placing in a warmer room or by submersing the assembled rebreather with
mouthpiece closed (loop sealed) until the temperature of the equipment matches the ambient
temperature. Below 0oC the liquid crystal displays in the handsets freeze to a solid black and are
unusable. Water is an essential part of the CO2 absorption reactions (approx. 17% of Sofnolime is
water), below freezing point the first reaction where CO2 and water react to form Carbonic acid
cannot take place. If a pre-breathing method of warming the Sofnolime is used, this must be done on
land under supervision.
Oxygen sensor life:
18 months from date of manufacture
Shelf life of unused rebreather:
When stored in accordance with BS3574 the shelf life is 7
years ( derived from the hoses and seals.)
Weight:
Medium Counterlungs and Medium harness - 29.2kg
Large Counterlungs and Large harness - 29.5kg
- 82 -
Sofnolime Data
Shelf life:
Refer to manufacturers packaging.
Grade:
1 - 2.5 mm Sofnolime 797 - Diving Grade
Storage:
Sofnolime must be stored in a sealed container within a clean dry environment at a constant
temperature (Ideally between 0 and 35oC). Storage at high temperature may cause reductions in the
efficiency and effective life span of the material. Storage at sub-zero temperatures should be
avoided.
Correctly stored sofnolime should maintain absorption capacity for up to five years.
Sofnolime must not be stored where it can become subject to the following:
i)
Strong Sunlight.
ii)
Contact with any other chemicals.
iii)
Contact with water.
iv)
Atmospheric conditions with higher than normal concentrations of acidic gases.
Transport: Sofnolime contains less than 3.5% w/w sodium hydroxide and therefore is not
classified as corrosive.1,2 Containers of Sofnolime do not need to be marked with any special hazard
warning and they can be shipped by road, sea or air as non-hazardous product.
Personal Protection: Sofnolime is mildly alkaline and care must be taken to avoid contact with skin
and eyes and to avoid inhalation of dust.
Spillages and Disposal:
If spillage occurs granules should be swept or vacuumed up and
disposed of appropriately. Any residue should be washed away with excess water. Exhausted or
waste Sofnolime will contain residual alkalinity but may be disposed of in a suitable land fill site.
Ambient Pressure Diving Ltd reserves the right to alter specifications without notice.
Notes:
1.
Recommendations on the Transport of Dangerous Goods, UN Forth Revised Edition, 1986.
2.
CPL Regulations Authorised Approved List, Health and Safety Commission, UK,
2nd edition, 1988.
- 83 -
SECTION 16
DANGERS INTRODUCED BY USER MODIFICATIONS
1) Do NOT change the 1st stages for environmentally sealed Apeks 1st stages. These sealed 1st
stages boost the Interstage pressure by more than ambient pressure when at depth. This will
stop the oxygen solenoid working and gas will also be lost through the pressure relief valve
(the Auto Air).
2) Do NOT use sealant or tape to “waterproof” the red oxygen cell covers. This prevents
adequate pressure balancing leading to incorrect readings on the ppO2 displays.
3) Do NOT attach anything to the hoses leading to the handsets. These robust hoses protect the
cables to the handsets and also keep the handsets at ambient pressure. If ty-raps (electrical
ties), are used around these hoses, the pressure balancing can be affected resulting in physical
damage during ascent or descent.
4) Do NOT change the mouthpiece for one with narrow bites. The bite determines how far
apart the teeth are held open. If your teeth are not far enough apart the induced work of
breathing is dramatic increasing retained CO2, which in turn increases susceptibility to
Nitrogen Narcosis, Oxygen toxicity, and decompression sickness.
5) If the Auto Air is removed, it must be replaced with a suitable downstream 2nd stage.
Additionally, if an isolator such as the APD Flowstop or Apeks Free-Flow Control device is
fitted in line with the 2nd stage, a suitable Pressure Relief valve, such as the RB17(14bar)
MUST be fitted to the 1st stage.
- 84 -
SECTION 17
DIVING DEATHS
“Whether divers die using open circuit equipment or rebreathers, they die for the same reason – they
are not aware of or fail to remain within the limitations of their kit!”
The easiest way to explain this is to give you some examples:
a) Many Open Circuit sport divers die because they run out of air, many struggle to the surface and
then find they can’t stay afloat and drown. So what went wrong? Was running out of air the problem
or was it simply their lack of planning/knowledge to deal with the situation from then on. The answer
is both of course, but fundamentally the real problem was lack of awareness in knowing the
equipment limitations: the gas needed to be monitored more closely during the dive and prior
planning was necessary to deal with that scenario should it occur. In this example when s/he got to
the surface it would have been a good idea to drop the weight-belt or inflate the BC from a 2nd air
source. So, the equipment choice and combination had to be correct, the diver then had to have the
ability to use the appropriate piece of equipment including the mental strength to use it. The mental
strength can be improved relatively easily: practise, practise, practise.
b) Increasingly, technical Open Circuit divers die through a combination of over-weighting and
breathing the wrong gas either in the shallows or deep.
c) Some leap over the side without turning the tank on, and then don’t have the equipment sorted or
due to lack of practise can’t deploy a 2nd mouthpiece.
The above “open-circuit” instances occur a lot, 20 to 30 times per year in the UK alone!
Rebreathers bring with them new opportunities but also new limitations of which the diver must
remain aware.
The following are identifiable reasons why divers die using rebreathers:
1) Over-use of the CO2 absorbent.
2) Improper equipment assembly, followed by inadequate monitoring of system(s).
3) Inappropriate equipment selection or combinations e.g. dry suit inlet valve hose tucked under
counterlungs making it impossible to disconnect in the event of a free-flow. New under-suit
hindering the dry suit exhaust.
4) Failure to switch on the handsets, followed by inadequate monitoring of system.
5) Use of low oxygen percentage diluents and breathing them near the surface either through an
open circuit valve or through the loop but then also failing to ensure the system is turned on &
actually adding oxygen.
6) Ignoring system warnings.
7) Failing to notice lots of bubbles, failing to monitor gas pressures, only having one bail out
method: Open circuit bailout is no use to you if you have no gas in the tank!
This list is not exhaustive but gives an indication of the importance of “Being aware”. Know the
equipment limitations; know how it is supposed to be working, know whether it is working as you
expect it to, be aware of how you feel – you are part of the loop too. Then practise and practise so
you can reach all the buckles and valves and think through the problem scenarios so you are better
mentally prepared to deal with issues as they arise.
Providing you are aware, rebreathers are safer than Open Circuit; they give you much longer to
resolve issues before they become life threatening.
- 85 -
APPENDIX 1
POWER ON
INSPIRATION
BEEP BEEP
[checks oxygen cells]
[cells okay]
[checks battery]
CELL n FAILURE
CELL n FAILURE
REPLACE
NO DIVE
[battery level < LOW]
LOW BATTERY
REPLACE
NO DIVE
[battery level LOW]
[battery ok]
BATTERY WARNING
REPLACE
DIVE NOW?
YES
NO
[Scans the communication link, looking for other unit]
[Other unit switched on and
already a Master]
[Other unit switched off]
Elapsed ON Time
nn hrs nn mins
SLAVE
Waiting for Data
DIVE NOW ?
Confirm
SLAVE 0.70
0.70
0.70 0.70
(Press the centre button to confirm)
DIVE MODE
CHECK DILUENT!
Confirm
A
- 86 -
A
[Reads the cells and checks the calibration values]
[If one cell’s output is out of range
compared to the other two]
[If all 3 cells are within range]
CALIBRATE ?
Yes
No
Ambient Pressure
Down 1000mB Up
MUST CALIBRATE!
Yes
No
OPEN O2 VALVE!
Confirm
(700mB to 1050mB)
(Pressing Centre button enters selection)
OXYGEN %
Down 96% Up
Open Mouthpiece!
Confirm
OPEN O2 VALVE!
Confirm
FLUSHING BAG
0.34 0.27 0.40
MASTER 0.70
0.70
0.70 0.70
(21% to 100%, oxygen %
in the scrubber lid during
calibration)
DIVE MODE
Note: FLUSHING BAG: The solenoid valve is opened and oxygen injected until the cells
are stable. This takes between 5 and 34 seconds, depending on initial ppO2 of the loop. Do
not worry that all three cells are different at this stage. Once oxygen is injected and the cells
become stable note the readings just before calibration. This gives a first level indication of
the health of the cells. All cells should read between 0.70 and 1.30 which is the cell
manufacturer’s tolerance specification at 1000 mbar atmospheric pressure.
(Cell analysis during calibration)
NO OXYGEN
Check valve
CELL STUCK
NO CALIBRATION
CELLnFAILURE
Replace
OUT OF RANGE
NO DIVE
CELLnFAILURE
Replace
CALIBRATING
(this takes approx.
7 seconds)
NO DIVE
MASTER 0.70
0.70 0.71 0.69
NO CALIBRATION
DIVE MODE
- 87 -
APPENDIX 2
DETERMINING THE OXYGEN PURITY (WHEN THE GAS
QUALITY IS NOT CERTIFIED)
Section A
It is possible to analyse the gas using an independent oxygen analyser which has been calibrated on
pure oxygen. However, when travelling, there is little point in taking another analyser with you
when you already have three built into the INSPIRATION. Calibrate the INSPIRATION’s cells on a
known gas source before departure and on reaching the destination, select NO to any calibration
prompts. In the event of a MUST calibrate warning, select NO but then see Section B below.
Flush with Oxygen:
Open the mouthpiece and continually press the manual oxygen inflator, located on the exhale
counterlung. When the cell readings have stabilised, which will take approx. 20 seconds of continual
injection, record the cell readings on the oxygen controller. When the system is flushed with the
available oxygen the three subsequent ppO2 readings, one for each cell, will show the product of the
oxygen percentage and the ambient pressure. If the ambient pressure at the new location is known
then the exact oxygen percentage in the gas supplied may be calculated as follows:
Ambient Pressure (bar) x Oxygen Percentage in Gas cylinder =
100
If:
Displayed ppO2
ppO2 displayed
Ambient pressure
Quality of gas supplied
=
=
=
0.85
1036 mbar (1.036 bar)
unknown
=
Z
1.036 x Z
100
Z
=
0.85
=
0.85
=
x
100
1.036
82% (at the surface)
%
A dive may be carried out using the stored calibration settings or the apparatus may be recalibrated
using the now known oxygen content of the gas supplied. To recalibrate, switch the controller off
and then on again. When diving with less than 100% oxygen, buoyancy control will be more
difficult as more gas must be injected via the solenoid valve and it may take the controller longer to
reach the desired setpoints.
- 88 -
If the ambient pressure or the gas quality is not known assume the ambient pressure is 1 bar and then
calculate the oxygen percentage of the gas supplied:
1.0 x Z = 0.85;
so
Z = 0.85/1.0 = 0.85.
Whichever method is selected, the displayed figure will be 0.85 bar which is known to be accurate
because recently calibrated cells have been used to measure it. The problem with using this last
method is that if the ambient pressure changes due to atmospheric changes (usually obvious due to
climatic changes) or if the intention is to do some diving in mountainous areas, then it would not be
possible to rely on the system’s accuracy. A validation judgement would have to be made: i.e. know
that the actual ppO2 is going to be less (in the case of going into the mountains) than that indicated
and plan the decompression accordingly remembering that for every 50 mbar. (0.05 bar) drop in
ambient pressure the ppO2 is 0.05 bar less than that indicated.
Section B
‘MUST CALIBRATE’ warnings occur if one cell has drifted too far from the other two when
compared back to the last calibration values. When you have flushed the loop with the unknown
grade of oxygen, two of the three cells are likely to agree, the third giving a spurious reading.
Ignoring the spurious reading, insert the ppO2 displayed in the above formula to find the quality of
gas supplied. Use this data to then re-calibrate the oxygen cells.
- 89 -
APPENDIX 3
SELF CHECK QUESTIONS AND ANSWERS
a.
What are the risks when you first enter the water?
The biggest danger is jumping in with the oxygen controllers turned off. A quick look at the displays
verifies that all is functional and the cell values change as you breath. It is not unknown for divers to
jump in without turning on the diluent and ensuring the inflator hose is properly connected. Just
before you jump in - always press the diluent inflator button.
b.
What risks may become apparent during a surface swim prior to the dive?
Surface swims can be hard work. If the oxygen cylinder is empty or switched off or the oxygen
solenoid valve is faulty the oxygen level can drop quite rapidly. It is essential to look at the oxygen
display every minute.
c.
During the descent what is usually seen on the ppO2 display?
The ppO2 will rise during the descent.
d.
How often do you expect the solenoid to operate during the descent?
It is very rare for the solenoid to operate during the descent. The solenoid only operates if the ppO2
drops below the setpoint. The increasing ambient pressure keeps the ppO2 above the 0.7bar set point,
effectively preventing the solenoid from opening.
e.
Once below 23m what would be the effect of staying on the low (0.7bar) setpoint?
Below 23m the diver experiences more narcosis and has a greater decompression obligation than
open circuit air! This is particularly dangerous if the diver’s decompression planning is based upon a
1.25 bar setpoint.
f.
Once on the bottom how often would you expect the solenoid to operate and for how long
would the oxygen inject?
When at a steady depth the oxygen controller only adds the oxygen that you metabolise, so you
should expect short burst oxygen injections approximately every 30 seconds. The deeper you go the
shorter the bursts and longer the interval. So if you hear a long oxygen inject look at the displays.
g.
What is the effect of the ppO2 of adding diluent to the loop, for example after mask
clearing?
Adding diluent reduces the ppO2 if the unit is running normally at 1.3 bar. The degree of reduction
will vary with depth.
- 90 -
h.
i.
If a diluent flush is carried out at: 10m what will be the ppO2 in the loop?
0.42 bar
20m what will be the ppO2 in the loop?
0.63 bar
30m what will be the ppO2 in the loop?
0.84 bar
40m what will be the ppO2 in the loop?
1.05 bar
How often should you check your ppO2 whilst on the bottom?
Once per minute
j.
Why is it important to check your ppO2 prior to the ascent?
During the ascent the ppO2 will drop. If you have a low ppO2 in the loop the simple act of rising 3m
may be sufficient to lower the ppO2 sufficiently to cause a loss of consciousness.
k.
As you ascend how often would you expect the solenoid to operate and for how long and
how would this vary with ascent speed?
During the ascent the ppO2 drops, sometimes by as much as 0.2 bar. To counteract this the solenoid
operates for longer. Typically you might hear 3 second bursts with 6 second intervals. During fast
ascents the ppO2 drops more quickly, therefore, the O2 solenoid will open for longer bursts but still
with the 6 second interval between oxygen injections.
- 91 -
APPENDIX 4
DECOMPRESSION TABLES
The table below is reproduced from Proplanner.
To purchase a copy of the Proplanner Constant ppO2 Decompression Program - contact Phoenix
Oceaneering, Ferndown Industrial Estate, Ringwood, Dorset.
Other examples of Constant ppO2 Decompression Programs are available, at time of publication:
DDPlan – www.drogon.net & V-planner – www.v-planner.com
Ascent speed - 10m/min
Bottom time = time from leaving the surface to time leaving the bottom.
Decompression is an inexact science. All formulae and tables in existence, including this one, cannot
guarantee the user will not incur decompression sickness. Do the deepest dive first and avoid yo-yo
dive profiles.
Using ppO2 setting of 1.3 bar.
Open Circuit Bail Out on Air, with
(worst case accuracy assumed – ppO2 = 1.25 bar)
a gas switch at 4.5m to 99% oxygen.
Assuming INSPIRATION fails during the
last minute of bottom time.
DEPTH
BOTTOM
TIME
20m
140
150
170
1
2
2
3
4
60
70
80
90
100
120
1
1
4
6
9
12
17
1
3
6
8
11
13
17
30
40
50
60
70
1
1
3
8
11
16
1
1
3
3
5
9
12
16
30
40
50
1
2
5
10
15
1
3
4
6
10
15
25m
30m
35m
9m
1
6m
- 92 -
4.5m
9m
1
4
6m
4.5m
APPENDIX 5
BUDDY CLEAN DATA SHEET
Section 1A – Product Identification
Trade Name:
Buddy Clean Disinfectant/ Cleanser
Product Use:
Hard Surface Disinfection and Cleaning
Chemical Type:
Halogenated Tertiary Amine
Section 1B – Supplies Identification
Name and Address:
Ambient Pressure Diving Ltd.
Water-ma-Trout Industrial Estate
Helston,
Cornwall, UK.
TR13 0LW
Telephone No.:
01326 563834
Fax No.:
01326 573605
Section 2 – Hazardous Ingredients
Hazardous Ingredients:
None
Percentage by Weight:
N/A
LD50 of Material:
>4000mg/kg
Section 3 – Physical Data
Physical State:
Liquid
Appearance & Odour:
Colourless, slight natural colour, Available green with citrus fragrance
Evaporation Rate:
As Water
Boiling Point:
110oC
Freezing Point:
-20oC
% Volatile (by weight):
>95%
Solubility in Water (20oC):
Soluble
pH:
5 approximately
Specific Gravity:
1.02 @ 20oC
Section 4 – Fire & Explosion Data
Flammability:
Non-Flammable
If Yes, Under Which Conditions:
None
Section 5 – Reactivity Data
Chemical Stability:
Stable
Incompatibility:
If mixed with strong Alkalis, may neutralise or reduce disinfectant qualities
Hazardous Decomposition Products:
If burnt may produce
irritating fumes
Section 6 – Toxicological Properties
Exposure Route:
Degree of Hazard
– Skin Contact:
– Eye Contact:
– Inhalation Acute:
– Inhalation Chronic:
– Ingestion:
Low: Concentrate may act as a mild degreasant to sensitive skin
Low: Will Cause Irritation but no serious damage
Low: No significant hazard
Low: No significant hazard
Low: Substantial ingestion may cause irritation to mouth, throat and digestive tract
- 93 -
Section 7 – Preventative Measures
Personal Protective Equipment:
None required
Eye Protection:
Avoid contact with eyes
Leak & Spill Procedure:
Soak up onto inert material or may be flushed to drain with copious amounts of water
Handling Procedures:
Ensure good industrial hygiene
Storage Requirements:
Store between 0-30oC in dry conditions
Section 8 – First Aid Measures
State of Caution
Inhalation:
Non-Toxic: avoid long term inhalation of neat liquid. Remove to fresh air.
Eye Contact:
Rinse eyes with water. Seek medical advice if necessary.
Skin Contact:
Wash affected area with soap and water.
Ingestion:
Do NOT induce vomiting. Give copious milk or water. Seek medical advice where necessary.
Section 9 – Concentration
Buddy Clean is a neat solution and should be diluted:
Dilution rate:
Light soiling - 1:100
Heavier soiling - 1:50 with 20 minutes soak period.
If used in breathing circuits, rinse thoroughly with fresh water and allow to dry.
BUDDY Clean is not FDA approved for use in America; Silent Diving Systems LLC
(www.silentdiving.com) should be consulted for approved disinfectant in the USA.
- 94 -
APPENDIX 6
SOFNOLIME TRANSPORTATION DECLARATION
MOLECULAR PRODUCTS LTD
MILL END
THAXTED
ESSEX CM6 2LT
ENGLAND
We hereby certify that the Soda Lime (Sofnolime) manufactured by
Molecular Products Ltd contains less than 4% (Four Per Cent) Caustic Soda (NaOH)
is classified as non-hazardous and that it is not restricted for transport.
The label showing the corrosive symbol is a label for use of the product – not for
transport.
A Harding, Despatch Co-ordinator
For Molecular Products Ltd
- 95 -
Intentionally Blank
- 96 -
APPENDIX 7
TRIMIX IN THE REBREATHER
This is a guide ONLY, pointing out the limitations of the equipment. It is not the intention of this
manual to teach the diver how to dive using a pre-mixed helium based diluent, a separate course
should be undertaken for that, but it is essential to prepare a diluent with a suitable Equivalent
Nitrogen Depth (END) and a ppO2 of between 1.0 and 1.2 bar if the diluent were to be breathed open
circuit on the bottom or manually flushed through the breathing circuit.
Setpoint Considerations:
The maximum setpoint should be 1.3 bar. Avoid using a higher setpoint. If a higher setpoint
is used the high O2 alarm will be triggered occasionally – the deeper you are the more
oxygen molecules are injected per solenoid inject, giving slightly larger spikes per injection than
would be experienced at shallower depths. Additionally, a higher setpoint during the “bottom” phase
of a dive gives minimal benefit in decompression times but significantly reduces the oxygen toxicity
safety margin.
Diluent Considerations:
There are three considerations when choosing the diluent:
1) the ppO2 of the diluent at the deepest planned depth, must not exceed 1.3 bar to allow
effective diluent flushing. 1.0 to 1.2 bar ppO2 is common.
2) the ppN2 of the diluent affects the Narcosis and affects the density of the gas within the loop.
The increased density increases the work of breathing and reduces the scrubber duration.
Increased work of breathing increases retained CO2 which in turn increases the effects of
Narcosis, oxygen toxicity and decompression sickness. A ppN2 of 3.16 bar is suitable to
70m. Beyond 70m the ppN2 must be reduced: e.g. a ppN2 of 2.68 bar is suitable to 100m.
The table below shows suitable Trimix and possible HeliAir mixes.
Depth
END
Max.
PN2
PO2
Trimix, (O2/Helium)
HeliAir,
(O2/Helium)
50
60
70
80
90
100
30
30
30
28
26
24
3.16
3.16
3.16
3.002
2.844
2.686
1.3
1.3
1.3
1.3
1.3
1.3
“21:26”
“18:36”
“16:44”
“14:52”
“13:59”
"11:64"
"15:29"
"13:37"
"11:45"
"10:52"
"9:58"
"7:67"
3) the diver must carry a diluent that is life supporting (respirable) when breathed open circuit at
the surface. The deeper mixes are NOT respirable at the surface so it is clear an additional
cylinder with a higher oxygen content must be provided and care needs to be taken in
configuration and marking to ensure the diver doesn’t use the deep diluent’s 2nd stage when
close to the surface.
- 97 -
APPENDIX 8
EXPORT LICENSE REQUIREMENTS
The Inspiration rebreather is a dual-use product and whether new or 2nd hand requires an export
license if shipped outside the Country of use.
Critically there is an exception to this requirement, detailed as a footnote in Category 8A002q.
At September 2003 the UK’s Department of Industry specified the following:
Section 8A 002q: self-contained, closed or semi-closed circuit (rebreathing) diving and underwater
swimming apparatus. Note: 8A002q does not control an individual apparatus for personal use when
accompanying its user.
For the latest information see: http://www.dti.gov.uk/export.control/
Individual Countries may have alternative export license requirements and user’s should establish
these requirements for themselves.
- 98 -
APPENDIX 9
Pre Dive Check List
Perform the checks and tick the appropriate box prior to diving
Analyse diluent and O2 cylinder
Check diluent supply and oxygen cylinder pressures, and assemble into unit
Confirm correct operation of non-return valves
Assemble breathing hoses and mouthpiece, checking for any leaks
Check operation of mouthpiece and direction of gas flow through convoluted hoses, it should exhale
towards the diver’s right shoulder.
Carry out positive and negative pressure tests (see Section 1.14)
Turn on gas supply and check function of valves and bailout regulator systems
Check the Oxygen’s Interstage Pressure (it should be 7.5 bar). If the pressure is higher the solenoid may
not open, if the pressure is lower the solenoid may not close.
Switch on one Oxygen Controller ( Master )
Verify sufficient absorbent time remaining
Switch on second Oxygen Controller and verify proper function
Verify proper computer function
Verify correct calibration of O2 sensors
Check display for battery warnings.
Flush with air and check for low oxygen warning display and buzzer
- 99 -
Pre-Breathe Sequence
Prior to immersion the following pre-breathe check should be conducted to confirm the correct operation of the
Rebreather.
Select the LOW setpoint
Ensure the ppO2 drops rapidly as you exhale into the loop and check for slow changing cell values
Confirm the O2 control system properly maintains the setpoint for a minimum of 3 minutes
Verify ppO2 values using backup display (Slave Controller)
Confirm CO2 absorbent is functioning properly (pay attention for symptoms of hypercapnia)
Confirm operation of diluent and oxygen inflators (and ADV, if fitted)
Confirm operation of bailout systems
Ensure both counterlungs are fastened down with the Fastex buckles
Check the mouthpiece valve is fully open. Partially open will allow water in.
In-Water Checks and Important Procedures
After entering the water and before descending, ensure the oxygen controller
is functioning.
Ask your buddy to do a “bubble check” at 6m (20ft) on your equipment. It is easier to
abort the dive at 6m (20ft) and surface to fix any leaks.
Add DILUENT during the descent. It is dangerous to confuse the diluent
and oxygen inflators. Adding oxygen will cause a high ppO2 in the breathing loop
Once on the bottom, or below 20m, switch the setpoint to the HIGH setpoint.
Ensure the HIGH setpoint is maintained throughout the dive and is appropriate for the planned
decompression schedule.
During the ascent, dump the expanding gas by pulling the exhaust valve override or by exhaling around
the mouthpiece, or through the nose. No later than 4m, switch back to the low setpoints.
KNOW YOUR ppO2 AT ALL TIMES !
- 100 -
Post-dive actions
Stand the unit upright or lean gently forward onto the counterlungs. DO NOT lay
down on it’s back.
Remove the mouthpiece and hose assembly by unscrewing from the T-pieces, drain
and if required, rinse with fresh water, ensuring the non-return valves work properly
prior to storage
Check the scrubber for water and drain off excess
Dry the scrubber lid shaking off (gently) excess water and leave to air dry. Once
dry, re-assemble to the scrubber.
Remove the unit from direct sunlight (put a towel over it, if there is no shade)
Leave cylinder valves open until all the day’s diving is finished
Conduct post-dive maintenance:
Rinse counterlungs, valves and BC with fresh water.
- 101 -
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