TDI Inner Space Sytsems Megalodon Closed Circuit Rebreather Course

1. TDI Inner Space SytsemsMegalodonClosed Circuit Rebreather Course

2. Overview of Course Structure TDI Megalodon Closed Circuit Rebreather Diver Course • 1 - Introduction and Welcome • 2 - The History and Development of Rebreathers • 3 - Mechanics of the Megalodon • 4 - Electronics • 5 - Physiology - A Reflection for the CCR Diver

3. Overview of Course Structure continued TDI Megalodon Closed Circuit Rebreather Diver Course • 6 - Let’s Go Diving the Rebreather - Preparation • 7 - Let’s Go Diving the Rebreather - In the Water • 8 - Avoiding Rebreather Incidents - Safe Diving • 9 - Mod 2 Extension (Optional extra course) • 10 - Mod 3 Extension (Optional extra course)

4. TDI ISC Megalodon Rebreathers Diver Course Section 1: Introduction and Welcome

5. Introduction and Welcome • Welcome to a new way of thinking about diving • Understand that you are ALL novices again • You will develop new skills for CCR diving including: • Attitudes • Disciplines • Awareness

6. Introduction and Welcome Who the course is for and what you can expect to get out of it. • COURSE PREREQUISITES • 18 years of age • Logged 100+ dives • Nitrox and Advanced Nitrox training • COURSE CREDENTIALS • To become qualified to dive the Inner Space Systems Megalodon on Air Diluent up to 40m/132ft with safety stops and 5 minutes max deco at 6m/ 20ft

7. Introduction and Welcome • Why CCR Diving • Longer dive durations possible with very little equipment • Almost silent and bubble free unless ascending • Extremely efficient use of breathing gas • Optional Nitrox mix for all depths according to user-selectable PPO2 setpoint • Warm and moist comfortable breathing gas reducing risk of hypothermic tendencies

8. Introduction and Welcome • What else can you expect to experience on this course? • Many new terms for CCR not used in OC or SCR diving • Change from a constant percentage Nitrox mix in OC to a variable percentage Nitrox mix with constant partial pressure in CCR mode • Computer controlled gas injection system on ascent causes accelerating bouyancy characteristics • We need to think differently • Jump a billion years of evolutionary development • An opportunity to almost evolve into a sea-going mammal with hours of sub-surface capability, and be back on land again for another fun filled experience

9. TDI ISC Megalodon Rebreather Divers Course Section 2: The History and Development of Rebreathers

10. The History and Development of Rebreathers • Rebreathers in basic form have been around for over a century underwater, and longer for mine rescue work • The earliest makes were pure oxygen devices • The Englishman Henry Fleuss achieves a major milestone covering over 300 meters (1000 feet) underwater in the construction of the Severn railway tunnel a century ago • Military rebreathers developed and used-Stealth

11. The History and Development of Rebreathers • The advent of readily available Nitrox to the recreational market fuelled the development of recreational nitrox SCR rebreathers • Progress and need in the military theater saw the development of a number of electronic controlled CCR machines over the last two decades • Some cave divers opted for passive mechanical SCR with no electronics • Makes include the Electrolung; Cis Lunar; Drager Atlantis, Dolphin and Ray and Inspiration/Evolution. • We see the advent of recreational CCR’s with the Inspiration in 1997, followed by Prism, Megalodon,Ouroboros, Optima and Kiss, and in 2005 the Evolution

12. The History and Development of Rebreathers CONCEPTUAL REBREATHER DESIGN • All need a scrubber for CO2 removal • Pure Oxygen rebreather – no need for electronics in basic form just keep manually adding gas when loop volume falls • Semi Closed SCR uses a known nitrox for loop addition • Mechanical rebreathers use a fractional volume technique to refresh gas • Either Passive by sucking in fresh gas when oxygen in the loop volume is depleted and a diaphragm regulator re-injects to bring loop volume back up, or • Active – Constant flow rate of Nitrox to loop-vent excess

13. The History and Development of Rebreathers Megalodon Rebreather • Closed Circuit rebreathers (CCR) • State of the art electronic controls • Onboard sources of air and oxygen, scrubber, computer controlled variable Nitrox mixing • Everything the recreational and technical diver needs

14. TDI ISC MegalodonRebreather Diver Course Section 3: Mechanics and basic functioning of the Megalodon rebreather

15. Mechanics and basic functioning of the ISC Megalodon • Diver’s Lungs • DSV and Hoses • Exhalation Counterlung • Manual Inject Buttons • Over Pressure Release Valve • The Scrubber • The Scrubber Cartridge • The Head and handsets • Three Independent Oxygen Sensors • The Handsets and Gas Control • Battery Compartments • Cell Connectors • The Oxygen Supply • Inhalation Counterlung • Diluent Gas Supply • Heads Up Display

16. Mechanics and basic functioning of the ISC Megalodon • Including Optional System Components • Auto-Diluent Additional Valve (ADV) and inline LP Flow Stop control device • Tiger Gear Mounting System • Mixed Gas Bypass • Radial scrubber • Neoprene Counter Lungs • Choice of Different Back plates and wing Sytems

17. Mechanics and basic functioning of the ISC Megalodon DIVERS LUNGS • The motor that powers the gas around the rebreather gas loop • The point of exchange for O2 rich gas to the body and CO2 rich gas from the body • When we inhale, “clean” O2 rich gas comes in from the Right. • The flow is from the divers lungs through the mouthpiece to the Left

18. Mechanics and basic functioning of the ISC Megalodon MOUTHPIECE and HOSES • Mouthpiece and one-way mushroom valves control direction of gas flow • Timing of gas flow is in sympathy with diver’s breathing pattern. • Hoses are large bore. This reduces the work of breathing (WOB) • (Always close the mouthpiece to prevent fluding)

19. Mechanics and basic functioning of the ISC Megalodon EXHALATION COUNTERLUNG • Counterlungs come from the factory as standard 5.5 ltr lungs made from highly durable cordura. (Neoprene Counter lungs can be order from ISC) • Flexible breathing bag to contain gas from body • Contains both the ADV, Mixed Gas By-pass (Additional Extra) and the Gas Loop Over Pressure Release Valve

20. Mechanics and basic functioning of the ISC Megalodon THE CO2 SCRUBBER (or Stack) • Gas path is from the exhalation counterlung, through the T-piece down to the bottom of the CO2 scrubber • It fans out to a large bore axial flow through the scrubber to reduce gas velocity and increase “Dwell Time” for CO2 removal • The scrubber can is clear allowing the diver to see the Internal Dive Sorb.

21. Mechanics and basic functioning of the ISC Megalodon THE SCRUBBER CARTRIDGE • Designed to remove CO2 from the gas loop. • Situated on a spacer fitted with moisture pads to maintain air gap at bottom and soak up an moisture from the canister

22. Mechanics and basic functioning of the ISC Megalodon The Scrubber Cartridge – continued • Different scrubber makes can give different duration times due to different granule sizes • Only designed to remove CO2, not any other toxic compounds or contaminants in the breathing gas

23. Mechanics and basic functioning of the ISC Megalodon SCRUBBER MATERIALS • Have a defined shelf life time and in use up to 3 hours • Effectiveness altered by time, temperature and moisture • Sofnolime 797 grade recommended ( Other makes include Dragersorb and Sodasorb) • Sofnolime is primarily a Sodium Hydroxide compound • Needs proper packing to prevent CO2 channeling • Efficiency is reduced by high gas flow rates (fast or skip breathing) or focused “channeling” characteristics • In a properly assembled and properly functioning CCR system the CO2 scrubber is the “Achilles Heel”

24. Mechanics and basic functioning of the ISC Megalodon SCRUBBER MANAGEMENT • No partial filling of the scrubber. New full canister every time • Do not empty scrubber into a bag and re-pack the scrubber later- new and used granules are then mixed • Do not store partly used scrubber for more than a few days. The material absorbs CO2 and grows mold

25. Mechanics and basic functioning of the ISC Megalodon CONTROLLERS GENERAL • Power On • Primary and Secondary Electronics • Switch on manually • Self testing electronics. • (hear solenoid firing, HUD Flashing) • 2 control buttons. • Sleep mode to conserve power ELECTRONIC WORKSHOP

26. Mechanics and basic functioning of the ISC Megalodon HANDSET CONTROLLER GENERALITIES • Handset controllers are electronic – handle carefully • There are two independent handset “controllers” on the ISC Megalodon and a HUD • The main function of the primary controller is to control oxygen injections and display real time information to the diver • The main function of the secondary controller is to provide the diver with a totally independant PO2 reading. • Can be switched on and off separately

27. Mechanics and basic functioning of the ISC Megalodon CONTROLLER FEATURES • User Selectable Setpoints • Built in System Monitor (Mv, Battery output, Temperature) • Back light feature • User Selectable Oxygen Injection Time • Metric - Imperial / Fresh - Salt water • User selectable O2 % for Calibration.

28. Mechanics and basic functioning of the ISC Megalodon THE PRIMARY HANDSET • Redundant controller PPO2 readings displayed to the diver • Responsible for driving the Solinoid • Requires independant Calibration. • Primary Handset has a SSI (System Status Indicator +&- ) • Must be switched on to have a chance to drive the oxygen solenoid • Will give indications of battery health (load / no load), Cell health, Loop Temp, Outside Temp. • Redundancy so that 1 controller can fail while the other allows you to safely exit the water • Need to constantly be checking PPO2 on the handset No Audio Alarm.

29. Mechanics and basic functioning of the ISC Megalodon THE SECONDARY HANDSET • Redundant controller PPO2 readings displayed to the diver • Passive Heads UP Display (All HUD functions are controlled by the secondary Handset) • Requires independant Calibration. • Will give indications of Battery health, Cell health, Loop Temp, Outside Temp. • Need to constantly be checking PPO2 on the handset No Audio Alarm.

30. Mechanics and basic functioning of the ISC Megalodon HEADS UP DISPLAY (HUD) • Three Colour Indicator powered by the secondary handset • Can be disabled by the diver • Adjustable Brightness control • The HUD works by benchmarking setpoint 1.0 in ORANGE • Cell Readings Higher than 1.0 are indicated by blinking GREEN • Cell Readings Lower than 1.0 are indicated by blinking RED • Each Cell will blink seperately with a short pause between each announcement.

31. Mechanics and basic functioning of the ISC Megalodon THE CANNISTER “ LID” • The electronic “brains” of the device • Consisting of two indipendant Battery packs, wiring for the handsets and HUD, Oxygen Sensor Pod & Solinoid • Great care should be taken when handling them • For transport fully assemble rebreather or carry lid and handsets separately in a padded bag • Treat it with the same care as a laptop

32. Mechanics and basic functioning of the ISC Megalodon 3 INDEPENDENT OXYGEN SENSORS • 3 galvanic fuel cells each with a milli-volt output proportional to the oxygen exposure across their outer faces (breathing gas) • The computers oxygen control averages all three Cells togethor to provide the PPO2 • This information is displayed to the diver both handsets • Delicate pin connections • Should never smell of “toxic” or other vapors

33. Mechanics and basic functioning of the ISC Megalodon • CONSTANT PPO2 GAS CONTROL • Remember Dalton’s Law from Advanced Nitrox Pressure gas = FO2 x Pressure • At different depths (gas pressures) for a constant PPO2 controller setting we will have a Nitrox mix that changes proportionally to pressure • At any given depth we can calculate the Nitrox mix for any given PPO2 setting

34. Mechanics and basic functioning of the ISC Megalodon

35. Mechanics and basic functioning of the ISC Megalodon BATTERY COMPARTMENT • Two independant battery compartments • Sealed to atmospheric pressure • Battery packs consist of either 2 x 3.6v Lithium cells or 5 Alkaline batterys supplied by ISC WARNING! YOUR ELECTRONICS REQUIRE BATTERY POWER FOR OPERATION, ENSURE YOU HAVE ENOUGH POWER PRIOR TO EACH DIVE. CELLS READING 5.0V OR LESS SHOULD BE REPLACED

36. Mechanics and basic functioning of the ISC Megalodon CELL CONNECTORS • These are delicate and covered with red or blue moisture caps with holes for pressure equalization • Take great care not to damage wires or connectors if changing cells • Check Mv output from cells before each dive • Repalce your cells when Mv output falls below 9mv Your Instructor will run through the correct procedure for calibrating the handsets and conducting the required linearity checks

37. Mechanics and basic functioning of the ISC Megalodon THE OXYGEN SUPPLY • Dive tank switched on • HP to SPG on front of Inhilation lung gives O2 pressure • LP hose feeds O2 to the LID for the solenoid from the first stage regulator • First stage regulator I/P is usually 10 bar with a range of between 9.0 - 10.4 bar being acceptable • You can choose dive tank size to suit your requirements • Remember:- Rich mix Right, Lean mix Left

38. Mechanics and basic functioning of the ISC Megalodon DILUENT GAS SUPPLY • Need to use diluent below 6msw (20fsw) • Manually add diluent on descent depressing the ADV “to equalize” the loop volume with pressure changes • LP feeds to both the wing BCD and ADV • Tank pressure is displayed on the SPG via HP hose over left shoulder • Do not use for Drysuit inflation – use off board gas • IP normally set to 10 Bar WARNING The Megalodon CCR does not have on-board bailout, surficient bail out gas must be carried at all times.

39. TDI ISC Megalodn Rebreather Divers Course Section 6: Physiology – A Reflection for the CCR Diver

40. Physiology – A Reflection for the CCR Diver BASIC PREMISE • We need to breathe clean (CO2 and toxic gas free), appropriately oxygenated gas at all depths at all times to sustain life and to minimise DCS risk • Appropriate nitrox mixes are delivered to the diver under software control according to the PPO2 selected by the diver

41. Physiology – A Reflection for the CCR Diver ADDITIONAL CONCEPTS • Ascent must be controlled at less than 9m per minute as per normal diving practice. DSC and DCI risks still apply • Dangers of hypoxia, hyperoxia, asphyxia and the insidious CCR carbon dioxide poisoning (hypercapnia) need examination • Lets review sources of contamination of breathing loop • NOAA toxicity guidelines apply for Whole Body and Pulmonary Toxicity

42. Physiology – A Reflection for the CCR Diver CO2 and HYPERCAPNIA • Humans consume O2 at a cellular level and generate CO2 as a waste product • Blood transports O2 to the cells and removes CO2 • Blood exchanges CO2 for O2 at the lung Alveoli • The urge to breathe is driven by the level of CO2 retained in the body (blood and cells) • With hypercapnia and elevated CO2 levels, the breathing rate is increased (panting – dypsnea) to try to vent the lungs and alveoli

43. Physiology – A Reflection for the CCR Diver HYPERCANPNIA SYMPTOMS • Mild Symptoms • Headache • Anxiety and dizziness • Shortness of breath • Severe Symptoms • Strong anxiety bordering on panic • Muscular difficulty and loss of dexterity in closing mouthpiece to bail out to OC • Diluent flush doesn’t seem to have any effect at first so divers often stop flushing when in fact they should continue flushing non-stop

44. Physiology – A Reflection for the CCR Diver RE-INHALATION OF CO2 • CO2 normally removed by Sofnolime scrubber • Conditions when this doesn’t occur properly • Scrubber expired or ignoring 3 hour duration rule • Strenuous activity on rebreather • Incorrect assembly of rebreather • Wet or flooded scrubber • Damaged mushroom valves – gas goes backwards • Skip breathing or breath holding – creates pockets of very high CO2 content in the breathing loop • Incorrect scrubber packing

45. Physiology – A Reflection for the CCR Diver DEPTH VERSUS CO2 • As depth increases, work of breathing increases to push more gas molecules around the breathing loop. More CO2 is generated as a result. • As gas density of molecules increases the efficacy of the scrubber granules to absorb CO2 across its surface decreases

46. Physiology – A Reflection for the CCR Diver HYPEROXIA • Too much oxygen results in O2 toxicity risk • Track O2 toxicity per NOAA tables (see manual) • At a default setpoint of 1.3, NOAA limit = 180 minutes - But 80% of that is 144 minutes • Do not exceed 80% of CNS and OTU tables • Need to monitor CNS% and OTU’s carefully on multi-dive days or multiple repeat dive days

47. Physiology – A Reflection for the CCR Diver SYMPTOMS OF HYPEROXIA • CONVENTID • CON Convulsions • V Visual disturbances/Tunnel vision • E Ears ringing (Tinnitus) • N Nausea • T Tingling or twitching (facial) • I Irritability • D Dizziness or vertigo

48. Physiology – A Reflection for the CCR Diver PULMONARY TOXICITY • O2 causes the alveoli surfaces in the lung to dry out thus slowly reducing lung efficiency • OTUs – 1 minute of 100% oxygen breathing at the surface • Happens above a PPO2 of 0.5 thus very real danger for CCR Divers

49. Physiology – A Reflection for the CCR Diver HYPOXIA • Occurs if the PPO2 drops below 0.16 at any time • Real danger on ascent if solenoid fails • Real danger if Oxygen tank is off or empty • Symptoms can typically be breathlessness and panting, and lack of co-ordination • Unconsciousness resulting in drowning can be sudden and without warning

50. Physiology – A Reflection for the CCR Diver CNS TOXICITY AND OTU’s • Real danger of convulsing and drowning if your CNS is not monitored properly • Always know the PPO2 in the loop and do a diluent flush to check any odd readings • Track your CNS % and OTU’s on the NOAA tables in your manuals