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Wishlist: how can rebreathers be improved to make them even safer ?

Discussion in 'Rebreather Diving' started by Roger Hobden, Sep 2, 2018.

  1. Roger Hobden

    Roger Hobden Barracuda

    # of Dives: 50 - 99
    Location: Montreal
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    What technological changes do you wish were introduced into rebreathers to make them even safer then they currently are ?

    Edit: adding another question:

    Do you believe that in the future rebreathers will eventually become so safe that carrying bailout gas will never be necessary, only optional ?
     
  2. giffenk

    giffenk Great White

    # of Dives: 500 - 999
    Location: toronto
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  3. RainPilot

    RainPilot CCR Instructor Staff Member

    # of Dives: I just don't log dives
    Location: UAE
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    Genuinely accurate O2 sensors. The solid state ones seem to be doing it but time will tell.

    An accurate measurement of CO2 in the loop.

    Those 2 should cure the 3 H’s eventually.
     
    Doppler likes this.
  4. tbone1004

    tbone1004 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
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    that's about it. Not a whole lot else to them really.... Poseidon seems to have the O2 sensors sorted and we shall see if/when they really go fully out to the market, and CO2 is still in the works so we'll see if/when that comes
     
    Doppler likes this.
  5. northernone

    northernone Great White Rest in Peace

    # of Dives: 1,000 - 2,499
    Location: Currently: Cozumel, from Canada
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    I'd like it fully automated, redundant l and intigrated.

    No mouthpiece hold, no gauges to monitor, no loop to clean.

    Think pacemaker. Swap it out every few decades.

    At that level of dependability, a bailout would be silly. Like carrying a defibrillator in addition to a pacemaker.
     
  6. Roger Hobden

    Roger Hobden Barracuda

    # of Dives: 50 - 99
    Location: Montreal
    376
    110
    43
    I was thinking more about the near future ... :wink:
     
  7. northernone

    northernone Great White Rest in Peace

    # of Dives: 1,000 - 2,499
    Location: Currently: Cozumel, from Canada
    3,793
    3,394
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    As above, CO2 and o2 monitoring with better reliability.

    Also, rigorously tested designs. R&D to the quality standards of other industries. (A wish, yet making them prohibitively expensive so unrealistic)

    Cameron
     
    Roger Hobden and Fibonacci like this.
  8. hroark2112

    hroark2112 Tech Instructor

    # of Dives: 0 - 24
    Location: Raleigh, NC
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    I don't think it will get to the point where bailout is not necessary. Even if CO2 monitoring was in place and O2 sensors were perfect, there are still things that can happen. Loops can be compromised, hoses can tear, bad stuff happens.
     
    Roger Hobden likes this.
  9. Fibonacci

    Fibonacci Manta Ray

    # of Dives: 500 - 999
    Location: Melbourne, Australia
    571
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    Design Failure Modes and Effects Analysis (DFMEA) is a standard part of any modern Product Development activity... IF properly implemented as part of the early PD process (esp Design Brief stage!) it should not lead to excessive development costs vs unexpected catastrophic failures or even just recalls. However I agree unless volume is shared with the military, unit costs are likely to be much higher... and of course the military would be unlikely to allow the release of the same model onto the civilian market!

    Quite a good FMEA summary here:
    http://effectivefmeas.com/uploads/Failure_Mode_and_Effects_Analysis__FMEA__for_publication.pdf

    Let me stress I am NOT a rebreather diver, but interested in these systems from a design and engineering POV.

    According to a study by Dr Andrew Fock 'Killing them Softly':
    With the caveat that they are “best guess numbers,” Fock concluded that rebreather diving is likely five to 10 times as risky as open circuit scuba diving, accounting for about four to five deaths per 100,000 dives, compared to about 0.4 to 0.5 deaths per 100,000 dives for open circuit scuba. This makes rebreather diving more risky than sky diving at .99/100k, but far less risky than base-jumping at 43 deaths/100k.

    He found that there was no difference in fatality rates among manual or electronic units, or specific brands of rebreathers; accidents were roughly proportional to market share. Fock also pointed out that while the data suggests that deeper dives carry greater risks, a large number of rebreather fatalities occur in shallow depths within the recreational envelope.

    As far as the causes or “triggers” that precipitated accidents, Fock concluded that the source of most problems was the human-machine interface, or so-called “pilot error,” involving assembly and pre-dive preparation, maintenance, training, and high risk behaviours that include ignoring checklists, carrying insufficient bailout and diving beyond one’s limits. “The question,” posed Fock,” is whether the risk can best be mitigated by training (reinforced by dive culture), or engineering out potential problems, or both.”
    Rebreather diving: ‘Killing Them Softly’ | DIVER magazine

    Currently, one of the biggest safety issues surrounding rebreathers is the fact that divers become complacent and don’t rigorously adhere to a pre-dive checklist in assembling and preparing their unit for diving as they (presumably) learned in class, and also neglect required post-dive maintenance. (Some experienced rebreather divers don’t follow checklists either.) Even worse, some divers choose to dive knowing that there are problems with their unit such as a faulty sensor or small leaks.
    Creating A Safety Culture | DIVER magazine

    So will creating new expensive high-end fully integrated 'fly by wire' rebreather technologies for the recreational dive market make the situation better or worse... if the diver feels they can then rely 100% on it?
     
  10. joshk

    joshk Barracuda

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    I don't think open circuit is so safe that I'd only dive a single tank. Why would I dive a rebreather with no alternative system?
     
    Roger Hobden likes this.

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