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BSAC Rebreather Diving. Rebreather Fundamentals. Try-dive outline. Theory Rebreather Fundamentals Marshalling Rebreather Divers (optional) Dry Session Unit configuration & operation 2 students per instructor Own mask & fins Tee-shirt / pool suit recommended Be ready on pool side - PowerPoint PPT Presentation
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BSAC Rebreather Diving
Rebreather Rebreather FundamentalsFundamentals
Rebreather Rebreather FundamentalsFundamentals
Rebreather Fundamentals
Rebreather Fundamentals Try-dive outline
Theory Rebreather Fundamentals Marshalling Rebreather Divers (optional)
Dry Session Unit configuration & operation
2 students per instructor Own mask & fins Tee-shirt / pool suit recommended
Be ready on pool side
Try-dive Unit start-up & functional checks Try-dive (20 minutes) Shut down procedures
Rebreather Fundamentals
Rebreather Fundamentals Aims
Why Dive a Rebreather?
Rebreathers in Practice
Simple Rebreather Semi-Closed Rebreather Closed Circuit Rebreather
Buddying a Rebreather Diver
What If?
Rebreather Fundamentals
Rebreather Fundamentals Why Dive a Rebreather?
Gas extender Breathing rate independent
Decreased gas usage Easier Logistics in remote locations
Nitrox benefits Longer bottom times, i.e., increased no stop times Reduce potential for DCI
Warm, moist breathing media Reduced chilling No dry throat Less dehydrated
Reduced breathing effort
Reduced effect on the environment Reduced bubbles Reduced noise Get closer to marine life
Rebreather Fundamentals
Rebreather Fundamentals Longer Gas Duration
0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51
0
20
40
60
80
100
120
140
160Consumption
rate (l/m)
Depth (m)
CC
SCR
OC (25)
Metabolic Consumption 1 litre of oxygen / minute CCR 20 bar oxygen per hour (3 litre cylinder) SCR <= 10 l/min supply gas independent of depth OC depth & workload dependent
Rebreather Fundamentals
Rebreather Fundamentals PO2 Advantage
0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60PO2
Depth (m)
OC
SCR
CC
Inspiration Maximises PO2
SCR as per Nitrox
Rebreather Fundamentals
Rebreather Fundamentals Decompression limits
Longer decompression no stop limits
12 15 18 21 24 27 30 33 36 39 42 45
0
50
100
150
200No stop time (mins)
Depth (m)
Air
Nitrox
PO2
Rebreather Fundamentals
Rebreather Fundamentals
Meticulous attention required to: Unit maintenance & preparation Personal dive skills
Additional procedures Initially daunting Become normal diving practice
Non-rebreather buddies Need to know what to expect Need to understand implications
Rebreathers in Practice
Rebreather Fundamentals
Rebreather Fundamentals Simple Rebreather
Counterlung
OxygenScrubber
Dump Valve
Breathing Loop
Rebreather Fundamentals
Rebreather Fundamentals Simple Rebreather
Simple RebreatherSimple RebreatherSimple RebreatherSimple Rebreather
Semi-closed Semi-closed Circuit RebreatherCircuit Rebreather
Semi-closed Semi-closed Circuit RebreatherCircuit Rebreather
Closed Circuit Closed Circuit RebreatherRebreather
Closed Circuit Closed Circuit RebreatherRebreather
Difference is in the way that the addition of oxygen is effected
Rebreather Fundamentals
Rebreather Fundamentals Semi-Closed Rebreather
Nitrox
Metering flow orifice (jet)
Bypass
Vent Valve
Off-board Bail–out
On-board Bail-out?
Rebreather Fundamentals
Rebreather Fundamentals Closed Circuit Rebreather
OxygenDiluent
Handsets
Buzzer
Oxygen sensors
(3)
Oxygen inject valve
On-board
bail-out
OptionalAuto
Demand Valve
Rebreather Fundamentals
Rebreather Fundamentals
Definition: Pressure imbalance between the
counterlungs and diver’s lungs in different body positions
Counterlung position higher
Compromise is over the shoulder! Example, APD Inspiration
Easier to exhale Harder to inhale, e.g., Dräger Dolphin
Easier to inhale Harder to exhale
Counterlung position lower
Static Lung Loading
Rebreather Fundamentals
Rebreather Fundamentals
Redundant gas supply
DSMB / surface detection aids
Both divers conduct most conservative dive profile
Must be familiar with how to rescue a rebreather diver:
CBL of rebreather diver Rebreather mouthpiece
implications
Buddying a Rebreather Diver
Rebreather Fundamentals
Rebreather Fundamentals
GasGaugeGag
Post entry & bubble checks
Swim around not
over
Vent loop
Buoyancy Buoyancy
Unit shut down
Monitor Gas
Supply & FO2
SCR Rebreather Diving
Rebreather Fundamentals
Rebreather Fundamentals
Start-up& function checks
Post entry & bubble checks
Set point change
Add diluent
Swim around not
over
Vent loop
Buoyancy Buoyancy
Set point change
Unit shut down
Monitor handsets
CCR Rebreather Diving
Rebreather Fundamentals
Rebreather Fundamentals What if………
If in doubt… Close mouthpiece then Bail-out!
Something goes wrong with the unit……
Rebreather Fundamentals
Rebreather Fundamentals Summary
Why Dive a Rebreather?
Simple rebreather Semi-Closed Rebreather Closed Circuit
RebreatherBuddying
What If…
Rebreather Fundamentals
Rebreather Fundamentals Questions?