CCR Diver Course

1. CCR Diver Course Sentinel

2. Sentinel Rebreather Layout

3. Sentinel CCR

4. Sentinel Key Features

5. System Layout

6. Sentinel Safety Features

7. Sentinel Safety Features CDM (Canister duration monitor). CDM comprises TPM (Temperature Profile Meter) and O2 injection counter. Auto-breathe breathing detection will turn unit on or; Auto turn on at 1.3 absolute pressure Manual turn on CO2 sensor option on Expedition Sentinel

9. Electrical Oxygen Sensors Critical components - redundancy Galvanic fuel cells Lead anode - gold plated cathode - potassium hydroxide solution Lead is oxidized producing small voltage between anode & cathode Individually calibrated Affected by humidity and temperature

10. Sentinel Oxygen Cells

11. Sentinel Oxygen Controller

12. SentinelPower On Screen

13. SentinelInterpreting the PO2 Display The PO2�s from the 3 Oxygen Cells are the most important data you have to monitor Do It Regularly! Compare the PO2 displays to each other and to the Set-point and the Backup Display Note the speed at which the PO2 changes a slow reacting cell probably indicates moisture on that cell�s sensing face If in doubt confirm with Diluent flushes

14. SentinelControlling Set-point Minimum Set-point System will maintain a minimum of 0.4 at all times with the unit turned on even on an open circuit bailout Auto breathe ensures automatic turn on at less than 0.17 PO2 Changing Set-point Set-point can be changed Automatically or manually underwater Auto Set-point modes can be set for bottom and deco PO2�s Set-point range 0.4 to 1.6 is allowable

15. Sentinel Primary Dive Screens

16. Sentinel Rebreather HUD

17. CCR Design and Functionality

18. Cylinder Considerations Diluent primarily used only during descents Oxygen is more likely to limit dive duration Larger cylinders can be added or off-board cylinders attached

19. The Counter lungs Necessary for free breathing Empty bottle vs. paper bag Constant Buoyancy Exhale: lung volume decreased & bag volume increases Inhale: lung volume increases & bag volume decreases Compare to Open-Circuit Scuba Position to minimize pressure differential between lungs and counter lung

20. Hydrostatic Effect Chest mounted bag - diver horizontal inhale less effort exhale more effort

21. Hydrostatic Effect Back mounted bag - diver horizontal inhale more effort exhale less effort

22. Hydrostatic Effect Shoulder mounted bags. Most positions: Inhale & exhale have a more balanced effort.

23. Resistive Work of Breathing. Gas flow within a unit Size of hoses and orifices generate a resistance to breathing Includes design of mouthpiece, mushroom valves, hoses, counter lungs etc Gas density and depth dependent: deeper dives net denser gas, net higher resistive WOB Workload also affects resistive WOB-more gas flow equals more obstructions and turbulence CE Test data important to review

24. Breathing Loop Absorbent canister for CO2 removal Exhaled gas passes through this and is filtered for CO2 Efficiency and work of breathing is related to size / types of granules Duration affected by temperature and gas density Design also affects the efficiency

25. Absorbent Canister Design Gas exposed to sufficient surface area of absorbent to remove CO2 Gas flow rate across absorbent allows sufficient time (dwell time) for chemical removal of CO2 Simple & correct packing to prevent �channeling� of absorbent Prevents excess moisture from reaching absorbent

26. Absorbent Canister Types

27. Axial Canister

28. Cross Flow Canister

29. Absorbent Canister Radial Flow System - gas enters center of �doughnut� cross section & radiates outwards through the absorbent (or from the outside inwards).

30. Absorbent Types Barium Hydroxide - the earliest form of absorbent used Lithium Hydroxide - long lasting and efficient, but must be carefully handled and is expensive Soda Lime - a commonly used absorbent available under trade names such as Sofnolime� and Dr�ger Divesorb�

31. Carbon Dioxide Absorption Typical diving grade soda lime absorbent 94% Calcium Hydroxide [Ca(OH)2] 4% Sodium Hydroxide [NaOH] 1% Potassium Hydroxide [KOH] <1% Silica (binding agent) Some types change color with use Do not rely on this as an indicator of use Should be slightly hydrated to ensure production of Carbonic Acid

32. CO2 reacts with water (vapor) to form weak Carbonic Acid Carbonic Acid reacts with base to produce salt (chalk), water, & heat Resultant chemical reaction produces a strong alkaline material

33. CO2 Absorbent Duration Variables Chemical composition Canister volume Temperature Exertion level (CO2 generation) Moisture level Gas density/depth Rebreather design

34. CO2 Absorbent Testing The Sentinel was tested using: 1 - 2.5 mm (797 Grade) Sofnolime granules Water temp 4�C Depth of 15m and 40m on air and 100m on Heliox CO2 production rate of 1.6l/m 40l/m breathing rate

35. SentinelCO2 Absorbent Duration At CE test rates on air at 40m, the canister will last 180 minutes At 100m on Heliox it will last 160 minutes Durations with other absorbents have not been tested and cannot be guaranteed and may vary considerably

36. Hypercapnia PCO2 0.02 ATA/Bar - doubles breathing rate (dyspnea) 0.06 ATA/Bar - distress, confusion, lack of coordination 0.10 ATA/Bar - severe mental impairment 0. 12 ATA/Bar - loss of consciousness, death CE CO2 limits and alarms on the Sentinel Expedition are at 5 milibar and 10 milibar

37. Sentinel Dive Procedures

38. Packing SentinelCO2 Absorbent Canister Empty used absorbent Remove absorbent stuck to walls Dispose of absorbent (use makers guidelines) Inspect cartridge and canister for damage Periodically flush canister with warm soapy water to clean residue. Ensure base screen slides up and down Repack canister exactly following instructions on the attached label

39. Face Masks Rebreathers have limited gas supply Well fitting mask to prevent leaks Repeated mask clearing depletes gas supply Full face mask allows U/W communications full face must have a bite mouthpiece to prevent CO2 build-up

40. Breathing Characteristics More natural breathing than Open Circuit Breathing resistance depends on location of counter lung and diver�s body position Water in loop increases breathing resistance Humid gas reduces dehydration of diver Warm gas reduces heat loss from diver Both effects should reduce the risk of DCS

41. Sentinel Pre-Dive Checks

42. Sentinel Pre-Breathe Sequence Pre-breathe 5 minutes open mouthpiece and breathe normally WITH NOSE BLOCKED. Continue breathing for at least 1 minute if the graph is still red after 5 minutes, suspect flooding if yellow/green graph is not eventually displayed

43. Basic Dive Procedures Initial in-water verification Descent - manual diluent addition Buoyancy control Monitoring PO2 Minimum loop volume Monitoring gas supplies Ascents

44. Initial in-water verification at 6 m Check for leaks Verify oxygen injection is working Verify ADV is operating Adjust buoyancy

45. Descents Counter lung collapses as ambient pressure increases Compensation by Automatic Diluent Valve (ADV) gas addition or manual bypass Rapid descents cause PO2 spikes Select low PO2 Set-point for descent or AUTO mode Switch to high PO2 Set-point at target depth or check AUTO switch has occurred.

46. Buoyancy Control No buoyancy changes during breathing cycle Buoyancy adjustments using lung volume therefore not feasible Counter lung collapses during descent & expands during ascent Buoyancy change from fully collapsed to fully inflated is considerable. Use correct counter lung counter-weighting (approx. 4kg) to ensure unit is slightly negatively buoyant.

47. SentinelPO2 Monitoring Hypoxia & Hyperoxia are real dangers in all rebreathers Frequent cross checking of Primary and Backup displays

48. Minimum Loop Volume Loop volume just enough for one normal breath Extra volume is wasted gas and added buoyancy PO2 stays closer to Set-point Test loop volume with ADV disabled.

49. Monitoring Gas Supplies Gas supplies used at much slower rate than OC, but monitoring is still necessary Small gas supply quickly used if there are leaks in the loop, frequent mask clearing or frequent ascents / descents O2 supply not diluent supply typically limits the dive duration

50. SentinelAscents Buoyancy changes due to expansion of the counter lung, BCD, and dry suit PO2 should not be allowed to drop The Sentinel will maintain close to the Set-point during a normal ascent due to its dynamic control algorithm Oxygen can be manually added if necessary

51. Failure Modes Emergency Scenarios Hypoxia Hyperoxia Hypercapnia Solenoid/injection system failures Complete electronics failure Open circuit bailouts

52. Sentinel CCR Skills Complete Pre-dive check sequence, including the 5 minute Pre-breathe (with CDM monitoring). Complete automatic and manual calibration of cells. In water leak and function checks. Open circuit bailout (including BOV use) and open circuit bailout ascents. Manual control of PO2. CCR removal and replacement at surface. Set-point switching and automatic Set-point control.

53. Sentinel CCR SkillsSee the training video and skills list for skill detail Delayed surface marker buoy use on CCR. Diluent flush. Oxygen volume drill. Simulated Hypoxia drill. Simulated Hyperoxia drill. Metabolic rate drill. Maintenance of PO2 between deco stops. Partial flood recovery drill. Cell disabling and manual PO2 control.

54. Sentinel CCR SkillsSee the training video and skills list for skill detail HUD (Head Up Display) use. Semi Closed (gas extender drill). Electronics monitoring. Gas sharing. Various multi-part training scenarios.

55. Rebreather Maintenance Disinfecting & cleaning CO2 seal O-rings Canister Hoses Counter lungs BCD

56. Testing If the unit fails the negative test and the fault is not easily recognisable. Turn on all gases. Make sure the solenoid and ADV sliders are open Close the OPV Close the mouthpiece (open circuit mode). Fully immerse the unit (hoses, mouthpiece etc.) with the cover removed and look for leaks. If no leaks are visible but the OPV slowly vents gas, then suspect either the ADV or the solenoid. To test the ADV for leaks, close the gas block shutoff and see if the OPV stops leaking. Service as required. To test the solenoid for leaks, close the gas block shutoff and see if the OPV stops leaking. Service as required.

57. Disinfecting & Cleaning Rebreather - warm, damp environment is ideal for bacterial growth Breathing loop regularly disinfected & dried thoroughly Safe disinfectants only � Virkon is recommended Incorrect cleaning agents may affect O-rings/counterlungs/mushroom valves O2 compatible lubricants only on HP parts silicone grease on all else

58. Disinfecting & Cleaning Full disinfect once a week Use only recommended disinfectant for all parts Stand part in solution for maximum of 10 minutes Fresh water flush Allow to dry

59. After Every Days Diving Flush hoses and mouthpiece with fresh water Re-pack absorbent, fill cylinders as necessary If using absorbent again, keep sealed in the loop. If excessive moisture around the sensors, remove and dry.

60. Post Dive & Storage Rinse exterior of unit Remove/dispose absorbent Clean absorbent canister Rinse/disinfect breathing bags & hoses For storage, leave cylinders partially filled Allow unit to dry, lubricate all O-rings Remove oxygen sensors

61. O-Rings Do not disturb O-rings unnecessarily Carefully inspect prior to reassemble Replace damaged O-rings Excessive lubrication not required Check O-ring grooves for damage O2 compatible lubricants only on HP parts Factory sealed compartments - don�t tamper

62. Hoses Check for visible damage after every dive Store in a carry case Do not carry unit by hoses Do not place heavy equipment on hoses

63. Counter lungs Keep dry (vented) when not in use. Beware of bugs crawling into counterlungs Check loop interface ports for damage to threads, etc. Use loop end caps

64. BCD Vital for buoyancy control & safety Visual inspections regularly Fully inflate and check for leaks, pre-dive

65. Summary Advantages of CCR greatly outweigh the disadvantages Correct training is obligatory