GO Rebreather Diver Course

DIVE TALK GO CLOSED CIRCUIT REBREATHER STEP BY STEP • Introductions • A little bit about us and the place! • About the course • What it takes to be a Dive Talk GO CCR Diver! • Equipment requirements • What we must have for the class! • Rebreather • Get to know about rebreathers in general! • Dive Talk GO CCR • Get to know about the unit! • O2, CO2, and Other Considerations • Problem-solving and emergency procedures! • Pre-Dive & Set Up • Hands-on work! • Dive Procedures • What to monitor to stay alive! • Chemicals • How they work! • Rebreather Considerations • Understanding how the rebreather’s parts affect their use! • Rebreather Physiology • Basic understanding! • Rebreather Maintenance • How to take care of your new toy! COURSE OVERVIEW • Course schedule • Academic Sessions • Confined Water/Pool Training • Open Water Dives RISKS • The sport of SCUBA diving has some risk and potential hazards • Inform you about the risks and ways to manage risks when scuba diving • Putting a regulator in your mouth and descending below the surface of the water means you accept the risks • That one of these hazards might seriously injure or even kill you • As your skills and experience progress you accept greater risks • In the Dive Talk GO course, you will be exposed to various diving environments as part of the curriculum, the risks are relevant and can be managed. YOUR SCUBA COURSE • No one can become a truly competent scuba diver in only a few hours • Comfort in the water takes repetition and practice • Please allow your instructor to transition you into this new environment • Training divers is what your instructor and Dive Talk Academy do best CERTIFICATION LIMITS • Diver qualified on specific rebreather • Dive Talk GO Closed Circuit Rebreather • Recreational CCR Diver certification limits • Depth limit: 100 fsw • No mandatory decompression PROGRAM CONTENT • Minimum 420 minutes of confined and open water dive time • Eight in-water sessions • One to two confined water sessions • Six to Seven open water dives • Two dives at least 78 feet (24 meters) • No dives deeper than 100 feet • No dives with required decompression REQUIRED EQUIPMENT • Dive Talk GO Closed Circuit Rebreather • Exposure suit suitable for the environment • Slate and pencil • Reel and surface marker buoy • Computer or depth gauge and timer • Knife, Z-cutter, or shears • Mask and fins CLOSED CIRCUIT REBREATHERS • Gas supply • Gas control mechanism • Electronic CCR • Mechanical CCR (constant mass flow) • Counterlung • CO2 removal system • Bail-out system
 RULES FOR SAFE CCR DIVING • Avoid complacency • Avoid distraction • Be a disciplined diver • Be a thinking diver • Always know your PO2 • Do not be cheap • Make the CCR your primary diving equipment • Practice bailout options periodically • Assume that any mechanical or electrical device will fail • Accept that emergencies taught during training will happen • Do not start dives with a known system failure ELECTRICAL OXYGEN SENSORS • Critical components – redundancy • Galvanic fuel cells • Lead anode – gold plated cathode – Potassium Hydroxide solution • Lead is oxidized producing a small current between anode & cathode • Individually calibrated • Affected by humidity and temperature OXYGEN CELLS • Critical components – redundancy • Galvanic fuel cells • Lead anode – gold plated cathode – Potassium Hydroxide solution • Lead is oxidized producing a small current between anode & cathode • Individually calibrated • Affected by humidity and temperature • Calibration is extremely easy and is performed on the assembled unit. CHECKING OXYGEN SENSORS • Checking the linearity of the O2 sensors • Linearity is checked to see if the output of the cell will track the O2 increase in a linear fashion; • No "humps" or "valleys" of mV output, from 21% to 100% O2 • Checking O2 sensors for current limiting • Current limiting is done either in a pressure pot or at depth to test PPO2 at 1.6 • Critical to monitor speed at which PO2 changes • Note the speed at which the PO2 changes • A slow reacting cell can occur by: ◦ A result of cell ageing ◦ A result of moisture build-up in the sensor’s face. Check your PPO2 Frequently! PHYSIOLOGICAL CONCERNS • Hypoxia (O2 deficiency) • Hyperoxia (CNS O2 toxicity) • Hypercapnia (CO2 toxicity) • Decompression Sickness • Chemical Injury Hypoxia, Hyperoxia & Hypercapnia may cause Loss of Consciousness with little or No warning! FAILURE MODES • Bail-out Scenarios • Hypoxia • Hyperoxia • Hypercapnia • Flooded loop • Complete electronics failure For all of these, the initial response should be to bail out to open circuit SCUBA!!! HYPOXIA • Lack of oxygen at cellular level • First signs at PO2 of 0.16 • Serious signs at PO2 of 0.10 • Lack of coordination • Confusion, euphoria, inability to think clearly, unconsciousness & death Hypoxia Can Lead to Unconsciousness & Death Without Warning • Procedure ◦ Switch to Open Circuit for one or more sanity breaths ◦ Switch back to Rebreather ◦ Diluent flush ◦ Check PO2 ◦ Manually add oxygen to desired PO2 ◦ Repeat until desired PO2 is obtained ◦ If PO2 Remains Low, Switch to Open Circuit & Bail-Out • Problems that lead to Hypoxia: ◦ Failure to turn oxygen on ◦ Oxygen feed line not connected ◦ Wrong gas in oxygen cylinder ◦ Failure to calibrate ◦ Failure to do predive checks ◦ Failure to monitor PO2 ◦ Running out of oxygen supply gas ◦ Mass flow orifice clogged HYPEROXIA • Excess of oxygen at cellular level • PO2 of 0.5 to 1.0 ATA/Bar • Whole Body Oxygen Toxicity • PO2 > 1.0 ATA/Bar • CNS Oxygen Toxicity • Convulsions underwater may result in drowning Hyperoxia Can Lead to Convulsion & Drowning Without Warning • Procedure ◦ If well above desired PO2, switch to Open-Circuit for one or more sanity breaths ◦ If slightly above desired PO2, simply flush loop to bring down ◦ Switch back to Rebreather ◦ Diluent flush ◦ Check PO2 ◦ Repeat until desired PO2 is obtained ◦ If PO2 remains high, switch to Open Circuit & Bail-Out HYPERCAPNIA • PCO2 • 0.03 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 This document contains more detailed procedures and technical data, which can be explored further upon request. Would you like to dive deeper into any of these sections?