Presentation on theme: "TDI Inner Space Sytsems Megalodon Closed Circuit Rebreather Course"— Presentation transcript:
1 TDI Inner Space Sytsems Megalodon Closed Circuit Rebreather Course
2 Overview of Course Structure TDI Megalodon Closed Circuit Rebreather Diver CourseOverview of Course Structure1 - Introduction and Welcome2 - The History and Development of Rebreathers3 - Mechanics of the Megalodon4 - Electronics5 - Physiology - A Reflection for the CCR Diver
3 Overview of Course Structure continued TDI Megalodon Closed Circuit Rebreather Diver CourseOverview of Course Structure continued6 - Let’s Go Diving the Rebreather - Preparation7 - Let’s Go Diving the Rebreather - In the Water8 - Avoiding Rebreather Incidents - Safe Diving9 - Mod 2 Extension (Optional extra course)10 - Mod 3 Extension (Optional extra course)
5 Introduction and Welcome Welcome to a new way of thinking about divingUnderstand that you are ALL novices againYou will develop new skills for CCR diving including:AttitudesDisciplinesAwareness
6 Introduction and Welcome Who the course is for and what you can expect to get out of it.COURSE PREREQUISITES18 years of ageLogged 100+ divesNitrox and Advanced Nitrox trainingCOURSE CREDENTIALSTo 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 DivingLonger dive durations possible with very little equipmentAlmost silent and bubble free unless ascendingExtremely efficient use of breathing gasOptional Nitrox mix for all depths according to user-selectable PPO2 setpointWarm 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 divingChange from a constant percentage Nitrox mix in OC to a variable percentage Nitrox mix with constant partial pressure in CCR modeComputer controlled gas injection system on ascent causes accelerating bouyancy characteristicsWe need to think differentlyJump a billion years of evolutionary developmentAn 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 andDevelopment 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 workThe earliest makes were pure oxygen devicesThe Englishman Henry Fleuss achieves a major milestone covering over 300 meters (1000 feet) underwater in the construction of the Severn railway tunnel a century agoMilitary 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 rebreathersProgress and need in the military theater saw the development of a number of electronic controlled CCR machines over the last two decadesSome cave divers opted for passive mechanical SCR withno electronicsMakes 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 DESIGNAll need a scrubber for CO2 removalPure Oxygen rebreather – no need for electronics in basic form just keep manually adding gas when loop volume fallsSemi Closed SCR uses a known nitrox for loop additionMechanical rebreathers use a fractional volume technique to refresh gasEither 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, orActive – Constant flow rate of Nitrox to loop-vent excess
13 The History and Development of Rebreathers Megalodon RebreatherClosed Circuit rebreathers (CCR)State of the art electronic controlsOnboard sources of air and oxygen, scrubber, computer controlled variable Nitrox mixingEverything the recreational and technical diver needs
14 TDI ISC Megalodon Rebreather Diver Course Section 3:Mechanics and basic functioning of the Megalodon rebreather
15 Mechanics and basic functioning of the ISC Megalodon Diver’s LungsDSV and HosesExhalation CounterlungManual Inject ButtonsOver Pressure Release ValveThe ScrubberThe Scrubber CartridgeThe 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 ComponentsAuto-Diluent Additional Valve (ADV) and inline LP Flow Stop control deviceTiger Gear Mounting SystemMixed Gas BypassRadial scrubberNeoprene Counter LungsChoice of Different Back plates and wing Sytems
17 Mechanics and basic functioning of the ISC Megalodon DIVERS LUNGSThe motor that powers the gas around the rebreather gas loopThe point of exchange for O2 rich gas to the body and CO2 rich gas from the bodyWhen 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 HOSESMouthpiece and one-way mushroom valves control direction of gas flowTiming 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 COUNTERLUNGCounterlungs 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 bodyContains 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 scrubberIt fans out to a large bore axial flow through the scrubber to reduce gas velocity and increase “Dwell Time” for CO2 removalThe scrubber can is clear allowing the diver to see the Internal Dive Sorb.
21 Mechanics and basic functioning of the ISC Megalodon THE SCRUBBER CARTRIDGEDesigned 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 – continuedDifferent scrubber makes can give different duration times due to different granule sizesOnly 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 MATERIALSHave a defined shelf life time and in use up to 3 hoursEffectiveness altered by time, temperature and moistureSofnolime 797 grade recommended ( Other makes include Dragersorb and Sodasorb)Sofnolime is primarily a Sodium Hydroxide compoundNeeds proper packing to prevent CO2 channelingEfficiency is reduced by high gas flow rates (fast or skip breathing) or focused “channeling” characteristicsIn 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 MANAGEMENTNo partial filling of the scrubber. New full canister every timeDo not empty scrubber into a bag and re-pack the scrubber later- new and used granules are then mixedDo 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 CONTROLLERSGENERALPower OnPrimary and Secondary ElectronicsSwitch on manuallySelf testing electronics.(hear solenoid firing, HUD Flashing)2 control buttons.Sleep mode to conserve powerELECTRONIC WORKSHOP
26 Mechanics and basic functioning of the ISC Megalodon HANDSET CONTROLLER GENERALITIESHandset controllers are electronic – handle carefullyThere are two independent handset “controllers” on the ISC Megalodon and a HUDThe main function of the primary controller is to control oxygen injections and display real time information to the diverThe 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 FEATURESUser Selectable SetpointsBuilt in System Monitor (Mv, Battery output, Temperature)Back light featureUser Selectable Oxygen Injection TimeMetric - Imperial / Fresh - Salt waterUser selectable O2 % for Calibration.
28 Mechanics and basic functioning of the ISC Megalodon THE PRIMARY HANDSETRedundant controller PPO2 readings displayed to the diverResponsible for driving the SolinoidRequires independant Calibration.Primary Handset has a SSI (System Status Indicator +&- )Must be switched on to have a chance to drive the oxygen solenoidWill 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 waterNeed to constantly be checking PPO2 on the handset No Audio Alarm.
29 Mechanics and basic functioning of the ISC Megalodon THE SECONDARY HANDSETRedundant controller PPO2 readings displayed to the diverPassive 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 handsetCan be disabled by the diverAdjustable Brightness controlThe HUD works by benchmarking setpoint 1.0 in ORANGECell Readings Higher than 1.0 are indicated by blinking GREENCell Readings Lower than 1.0 are indicated by blinking REDEach 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 deviceConsisting of two indipendant Battery packs, wiring for the handsets and HUD, Oxygen Sensor Pod & SolinoidGreat care should be taken when handling themFor transport fully assemble rebreather or carry lid and handsets separately in a padded bagTreat it with the same care as a laptop
32 Mechanics and basic functioning of the ISC Megalodon 3 INDEPENDENT OXYGEN SENSORS3 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 PPO2This information is displayed to the diver both handsetsDelicate pin connectionsShould never smell of “toxic” or other vapors
33 Mechanics and basic functioning of the ISC Megalodon CONSTANT PPO2 GAS CONTROLRemember Dalton’s Law from Advanced Nitrox Pressure gas = FO2 x PressureAt different depths (gas pressures) for a constant PPO2 controller setting we will have a Nitrox mix that changes proportionally to pressureAt 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 COMPARTMENTTwo independant battery compartmentsSealed to atmospheric pressureBattery packs consist of either 2 x 3.6v Lithium cells or 5 Alkaline batterys supplied by ISCWARNING! 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 CONNECTORSThese are delicate and covered with red or blue moisture caps with holes for pressure equalizationTake great care not to damage wires or connectors if changing cellsCheck Mv output from cells before each diveRepalce your cells when Mv output falls below 9mvYour 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 SUPPLYDive tank switched onHP to SPG on front of Inhilation lung gives O2 pressureLP hose feeds O2 to the LID for the solenoid from the first stage regulatorFirst stage regulator I/P is usually 10 bar with a range of between bar being acceptableYou can choose dive tank size to suit your requirementsRemember:- Rich mix Right, Lean mix Left
38 Mechanics and basic functioning of the ISC Megalodon DILUENT GAS SUPPLYNeed to use diluent below 6msw (20fsw)Manually add diluent on descent depressing the ADV “to equalize” the loop volume with pressure changesLP feeds to both the wing BCD and ADVTank pressure is displayed on the SPG via HP hose over left shoulderDo not use for Drysuit inflation – use off board gasIP normally set to 10 BarWARNING 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 PREMISEWe 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 riskAppropriate 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 CONCEPTSAscent must be controlled at less than 9m per minute as per normal diving practice. DSC and DCI risks still applyDangers of hypoxia, hyperoxia, asphyxia and the insidious CCR carbon dioxide poisoning (hypercapnia) need examinationLets review sources of contamination of breathing loopNOAA toxicity guidelines apply for Whole Body and Pulmonary Toxicity
42 Physiology – A Reflection for the CCR Diver CO2 and HYPERCAPNIAHumans consume O2 at a cellular level and generate CO2 as a waste productBlood transports O2 to the cells and removes CO2Blood exchanges CO2 for O2 at the lung AlveoliThe 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 SYMPTOMSMild SymptomsHeadacheAnxiety and dizzinessShortness of breathSevere SymptomsStrong anxiety bordering on panicMuscular difficulty and loss of dexterity in closing mouthpiece to bail out to OCDiluent 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 CO2CO2 normally removed by Sofnolime scrubberConditions when this doesn’t occur properlyScrubber expired or ignoring 3 hour duration ruleStrenuous activity on rebreatherIncorrect assembly of rebreatherWet or flooded scrubberDamaged mushroom valves – gas goes backwardsSkip breathing or breath holding – creates pockets of very high CO2 content in the breathing loopIncorrect scrubber packing
45 Physiology – A Reflection for the CCR Diver DEPTH VERSUS CO2As 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 HYPEROXIAToo much oxygen results in O2 toxicity riskTrack O2 toxicity per NOAA tables (see manual)At a default setpoint of 1.3, NOAA limit = 180 minutes - But 80% of that is 144 minutesDo not exceed 80% of CNS and OTU tablesNeed 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 HYPEROXIACONVENTIDCON ConvulsionsV Visual disturbances/Tunnel visionE Ears ringing (Tinnitus)N NauseaT Tingling or twitching (facial)I IrritabilityD Dizziness or vertigo
48 Physiology – A Reflection for the CCR Diver PULMONARY TOXICITYO2 causes the alveoli surfaces in the lung to dry out thus slowly reducing lung efficiencyOTUs – 1 minute of 100% oxygen breathing at the surfaceHappens above a PPO2 of 0.5 thus very real danger for CCR Divers
49 Physiology – A Reflection for the CCR Diver HYPOXIAOccurs if the PPO2 drops below 0.16 at any timeReal danger on ascent if solenoid failsReal danger if Oxygen tank is off or emptySymptoms can typically be breathlessness and panting, and lack of co-ordinationUnconsciousness resulting in drowning can be sudden and without warning
50 Physiology – A Reflection for the CCR Diver CNS TOXICITY AND OTU’sReal danger of convulsing and drowning if your CNS is not monitored properlyAlways know the PPO2 in the loop and do a diluent flush to check any odd readingsTrack your CNS % and OTU’s on the NOAA tables in your manuals
51 Physiology – A Reflection for the CCR Diver ASPHYXIALike strangulation it is caused by a shortage of oxygen and buildup of CO2Restrictions in the breathing loop like a kinked mouthpiece hose can cause itEasily noticed early in a diveIneffective or exhausted scrubber also can cause asphyxiaEventually results in unconsciousness
52 TDI ISC Megalodon Rebreather Divers Course Section 7:Let’s Go Dive the Rebreather - Preparation
53 Let’s Go Diving the Rebreather - Preparation EQUIPMENT ASSEMBLY and INSPECTIONPreparationAssemble the rebreather according to a checklist (refer to manual), initially under Instructor guidanceBe meticulous and do not get distracted
54 Let’s Go Diving the Rebreather - Preparation Pay particular attention to the following during assembly and inspection;Positive & negative pressure testsCylinder contents analysisCylinder pressure on SPGs• HUD LEDs functioning (if HUD used)• Listen for solenoid firing when handsets switched on• Switches on handsets working normally• Mushroom valve checks on the mouthpiece assembly• Wing and Auto-Air checks• Scrubber packing• Hose O-ring lubrication• Battery power levels
55 Let’s Go Diving the Rebreather - Preparation WEIGHTING AND TRIMEnsure the unit is well weighted at the top.Add to the sides on the waistband to trimMore weight needed if diving in a drysuit
56 Let’s Go Diving the Rebreather - Preparation MACHINE CALIBRATIONAbsolutely critical part of the preparation processAlways put in % of oxygen in the lid at 98% - all the air cannot be displaced from the lidIs the Mbar reading on the Megalodn handset are Automatically sensedMbar readings are critical for altitude divingWatch the cell readings rise during calibration and check for any “slow” or “limited” cellsYour Instructor will demonstrate correct calibration procedures
57 Let’s Go Diving the Rebreather - Preparation GETTING THE FEEL OF THE MACHINE ON LANDPutting on the machine for a “dry dive”Adjust straps to fit body correctly and tuck away loose endsPower up and sequence handset control through to dive mode under guidance of InstructorSelect your SetpointPut on mask to prevent breathing through noseBreathe on the machine while watching PPO2 readings on handsets listen for solenoid firing
58 Let’s Go Diving the Rebreather - Preparation Dry dive simulations (approx 30 minutes)These provide useful simulations in a safe environment for learning and troubleshooting
59 Let’s Go Diving the Rebreather - Preparation OVERFILLED BREATHING LOOPAllow loop volume to increase by injecting a little diluent.Get the feel of “over pressurized loop” inhibiting the exhale cycleRelease excess gas – repeat again
60 Let’s Go Diving the Rebreather - Preparation UNDERFILLED BREATHING LOOPExhale fully through the nose, twiceFeel the effect of too little pressure in the loop, difficulty inhaling properlyAdd gas using the ADV, for volume adjustment
61 Let’s Go Diving the Rebreather - Preparation NORMAL LOOP VOLUMEContinue normal breathing mode while seated or stationaryObserve PPO2 readings and how closely they follow the setpointListen to solenoid firing and ensure you are feeling fine on machine
62 Let’s Go Diving the Rebreather - Preparation GENTLE EXERCISEWalk about with the rebreather onSimulate moderate exerciseNotice breathing, rate increases, and solenoid firing more often than when at rest.
63 Let’s Go Diving the Rebreather - Preparation INCREASED WORK LEVELJog in place for a couple of minutes, or do a few squats with the machine on to raise heart and respiratory ratesObserve PPO2 tracking, hear solenoid firing and notice little or no change in loop volumeThe student should still feel fine and have no CO2 problems
64 Let’s Go Diving the Rebreather - Preparation SETPOINT CHANGESSwitch Setpoint when the PPO2 rises observe PPO2 on handset to ensure fuctionalityTest how long it takes to breathe the loop back down to a PPO2 of 0.4 at restREMEMBER! There or no audio alarms for High or Low Oxygen on the Megalodon the diver should be monitoring the handsets at all times.
65 Let’s Go Diving the Rebreather - Preparation OPEN CIRCUIT BAIL-OUTClose mouthpiece and come off the loopSwitch to OC bailout – take 3 breaths, return to the loop and open mouthpieceObserve loop volume increase as O2 is injected to bring PPO2 back up to setpoint because of the air you introduce to the loop
66 Let’s Go Diving the Rebreather - Preparation DILUENT FLUSHInject diluent using the ADVVent gas through by exhalingRepeat three times and observe reduction in PPO2. Listen to solenoid firing.
67 Let’s Go Diving the Rebreather - Preparation MANUAL GAS ADDITIONGive a small squirt of O2 with the manual addition button and observe the PPO2 readingRepeat the exercise with diluentRepeat to get a “feel” for the addition buttons
68 TDI ISC Megalodon Rebreather Divers Course Section 8:Let’s Go Dive the Rebreather– In the Water
69 Let’s Go Diving the Rebreather – In the Water Rule No 1If in doubt – bail out!Rule no 2If something feels wrong – it is!
70 Let’s Go Diving the Rebreather – In the Water DIVE PLANNINGSelect depth and time for a safe no-deco timeScrubber monitoring and planning (2.5 – 3 hour rule)Gas volume planning – enough for a bail-outOxygen planning – CNS% and OTUsIs this a repetitive dive?Thermal protection appropriate for conditions and duration of diveBrief team, do ABCs and enter the water underguidance of your Instructor
71 Let’s Go Diving the Rebreather – In the Water FIRST IMPRESSIONS IN THE WATERSilenceBubble-freeListen for the solenoid firingCheck PPO2 on the handsets every minuteDynamic bouyancy change caused by computer- controlled oxygenUnit is bouyant at shoulder level due to air volume in counterlungs and hosesAdd weight at the top for trimRemember – no matter how experienced you are on OC, you are now a beginner again
72 Let’s Go Diving the Rebreather – In the Water EARLY TECHNIQUE POINTERSDo not expect to get it right first timeTry to keep the loop volume at a minimum for comfortKeep a steady depth levelTry to maintain a horizontal, neutral bouyancy, attitude while swimmingUse vertical attitude only when testing skills under instructor guidanceBe generous with weighting (1 or 2kg over)
73 Let’s Go Diving the Rebreather – In the Water BASIC WATER SKILLS DEVELOPMENTMouthpiece opening and closing techniquesOpen Circuit bail-outDiluent flushes and checking PPO2 dropCheck diluent flush predictionsBouyancy normalisation while swimmingConstant checking of PPO2 on handsetsUnderstanding and reacting to alarm conditions (mostly simulated while on course)Loop volume control
74 Let’s Go Diving the Rebreather – In the Water BAD – DAS DRILLSIn the event of in-water problems, rely onBAD-DAS drillsB Bail-out to open circuitA Anxiety breaths (3)D Decide what to doIf returning to the loop, then:D Diluent flush – breathe fresh gasA Always know your PPO2 – check handsetsS Skills. Apply appropriate skills gained during training to overcome the problem
75 Let’s Go Diving the Rebreather – In the Water LOW O2 DRILLSManual flight1 Using O2 inflator2 Adding oxygen using O2 tank valve3 Using machine in semi-closed circuit modeLow oxygen danger1 Solenoid stuck closed2 O2 tank empty or switched offHandset failure or switched offIf both are blank, go open circuit or if gas volumes dictate, switch to semi-closedcircuit mode
76 Let’s Go Diving the Rebreather – In the Water HIGH OXYGEN DRILLSOpen circuit bailoutUse of diluent flush to drop PPO2Closing oxygen tank if solenoid fails open
77 Let’s Go Diving the Rebreather – In the Water MENU MODE DRILLSSequencing through menu commands in water to become familiar with functionalityChanging SetpointsObserve System MonitorObserve SSI indicator
78 Let’s Go Diving the Rebreather – In the Water HYPERCAPNIA DRILLSOpen Circuit BailoutDiluent flushesPractice/Practice/Practice
79 Let’s Go Diving the Rebreather – In the Water ELECTRONICS MALFUNCTIONSHandset and controller problemsCell errors or missing cellsPoor PPO2 tracking to setpointPossible Loop Floods
81 Avoiding Rebreather incidents – Safe Diving All the training in the world is useless if you do not adopt the following as your personal mantra for CCR Diving:Safe AttitudeSafe and enhanced AwarenessSafe and structured Discipline
82 Avoiding Rebreather incidents – Safe Diving OPERATIONAL MAINTENANCECheck battery connections are clean and dryEnsure handsets are cleaned in fresh water,Keep O-rings well cleaned and lubricated to prevent abrasion and other damage
83 Avoiding Rebreather incidents – Safe Diving REMEMBER DURING PRE-DIVE PREPARATIONProperly assemble and check according to a check listDo not get distracted during calibrationDo all the pre-dive checks and then “go live” for a short “dry-dive” to pre-breathe prior to entering water in order to ensure dynamic functionality of the machine
84 Avoiding Rebreather incidents – Safe Diving DIVE PLANNINGBreak dive into logical “waypoints” to do checks and flushes for safetyUsual waypoints_ 6msw (20fsw) bubble leak checkOn descent - switch to high setpointsOn reaching bottom - diluent flush and check guages and handsetsAfter pre-set time or leaving bottom - diluent flushOn ascent (10msw or less) - gas venting to control bouyancy
85 Avoiding Rebreather incidents – Safe Diving REMEMBER ON THE DESCENTDo a shallow (6msw/20fsw) bubble checkDescend slowly to control breathing loop volumeWatch the PPO2Switch to high setpoint according to plan
86 Avoiding Rebreather incidents – Safe Diving REMEMBER ON THE ASCENTPPO2 will drop, solenoid should fire, and oxygen should come into the loop quickly – rapid bouyancy increaseCheck PPO2 closely on ascent to reduce Hypoxic risk if there is insufficient O2 in the loopCarefully control ascent rate3 potential bouyancy devices – drysuit, wing and loop counterlungs
87 Avoiding Rebreather incidents – Safe Diving REMEMBER AT THE SURFACENEVER switch off the handsets or tanks at the surface above deep waterOnly shut down after equipment has been taken offYou still need to watch your PPO2 if you breathe on the loop at the surfaceIt’s the best snorkel you ever bought!!!
88 Avoiding Rebreather incidents – Safe Diving REMEMBER AFTER THE DIVEGas up again for the following diveCheck and replace batteries/scrubberas necessaryDisinfect and clean as necessaryConduct all other system checks to ensure correct functionality of cells and handsetsLog your dives
89 Avoiding Rebreather incidents – Safe Diving TDI Training and Manufacturers ManualsErrors and troubleshooting are well documented for referenceMaintain your own service log for batteries/scrubber and other service needsDocument your rebreather experiences