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Rebreather safety protocols

Discussion in 'Rebreathers Closed and Semi Closed Circuit' started by Wibble, Mar 10, 2015.

  1. Wibble

    Wibble Fish don't talk
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    As an open circuit diver I am curious as to how rebreather systems and protocols are in place to mitigate failures. For instance, I would have expected bailouts to be heavily practiced.
     
    #1 Wibble, Mar 10, 2015
    Last edited by a moderator: Mar 11, 2015
  2. furryman

    furryman hmmmm
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    As as mere foetus in the RB world, there are two mantras that I have already committed to heart just from reading the manuals. "Always know your pO2" and "if in doubt, bail out".
    I anticipate learning more when I start my training journey.
     
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  3. becky9

    becky9 Diving bore!

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    Whilst not protecting against failures as such, checklists are used to try and mitigate human error x
     
  4. Wibble

    Wibble Fish don't talk
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    Lets take bailouts. What's the protocol?
     
  5. becky9

    becky9 Diving bore!

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    At first sign of impending doom, bailout................

    .................. Actually he'll prolly be sitting on the boat next to jb., so no real need to worry ;) x
     
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  6. Doomanic

    Doomanic Dinosaur Wrangler
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  7. Wibble

    Wibble Fish don't talk
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    What I meant was.... as an open circuit diver, I just pull the dead reg out and shove another (live reg) back in the whole, then breathe.

    With a breaver, don't you have to chant the right spell, stroke a rabbit's foot, then put another reg in? Or less obtuse, don't you have to shut down the mouthpiece and slacken off a necklace, then get the (correct for the depth) bailout regulator shoved in the gob? Then breeeaaathhee...
     
  8. Zubar

    Zubar Active Member
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    As I understand it, the traditional way is kind of as you say which is close the mouthpiece, take it out (I would think no gag strap in use this way) then go onto appropriate OC reg.

    Or If you have a BOV fitted then one just flips a lever and the mouthpiece goes from CC to OC and breathes off whatever you have plugged into it. With this some peeps use a gag strap to hold the mouthpiece in in the event of a tox or some such bad shit happening.
     
  9. Wibble

    Wibble Fish don't talk
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    Dumb question time; are bailouts something that one would be intimately familiar with, in the same way as swapping from your primary to backup reg would be? Also, are there any issues with bailing out and bailing back? I.e. Does a bailout mean you're on your way back to the surface immediately?
     
  10. furryman

    furryman hmmmm
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    An RB diver I met recently described having to bailout onto a trimix blend, and "watching the pound notes rise to the surface with every breath" so yes, he was on his way up soonest to minimise the pain in his wallet.
     
  11. Joe

    Joe Active Member

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    I'm new to RB diving about 18 months now and about 55 hrs the deepest dive 43mts and the longest 105min, I have never dived open water without my stage. If computer says Bail I push lever 1/4 turn and I'm on my dil then onto the stage its just like switching to a stage on OC so not that hard.
     
  12. Badknees

    Badknees Meg Pilot (retired) and Forum KGB

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    Bailout cylinders are just that. once you've bailed then you need a bloody good reason to go back on to CCR.

    Bailout has the same protocols as deco gas ie know what's in the cylinders. Bottom and accelerated deco. But unlike deco mixes on OC, bailout is there for the oh shit moments.
    Once you've bailed you are going up. But now your run times will start to match OC because you aren't running fixed ppo2.


    My personal preference is rich on the right lean left. That's to say if I'm shallow then bail right. if deep bail left.

    All so my deep bailout is plumbed into a bailout valve (BOV) so if required it's a flick away. Depending on the mix (if it's hypoxic ) then I have the facility to switch which mix is feeding the BOV.

    Depending on depth and bottom time carrying enough bailout can become challenging. This must be discussed and planned pre dive. Anything below 80m then it's a team bailout. Even with 4 ali 80s having enough gas isn't always an opion. Where the team carry enough gas to get 2 members up.

    Add a CO2 hit and your bottom gas is going very quickly.

    An Ali 80 at depth with CO2 hit will go in a matter of minutes.

    BK
     
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  13. Wibble

    Wibble Fish don't talk
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    From experience with rebreathers, would it be reasonable to say that a fault normally develops before the dive, or is noticed in the first couple of minutes, i.e. when they're working, they tend to stay working. So would a bailout on the bottom mean it's something pretty catastrophic and also fairly uncommon?

    I'm also curious as to the protocols. I've seen a RB class with their pretty long checklists. Once you've gained some experience, can complacency kick in and skipping checklist items becomes common? Sort of directing this at BK - with all your experience, do you still go through a rigid checklist? (This isn't in any way accusative nor looking for admissions of anything, it's purely a general question from a simple OC diver!!)
     
  14. Badknees

    Badknees Meg Pilot (retired) and Forum KGB

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    Check lists are followed on most units.pre dive and post dive.. And yes the pre dive and pre breath tests MUST be done missing them and it's a whole world of shit comING your way.
    If you dive CCR then you must be prepared to sit a dive out. Going in with an issue is madness. If you dive a sentinel then you will be sat out more than you dive. ;)

    The meg is a good solid unit but I've sat dives out because of an issue. Once had a loop hose tare at the end of the pre breath... that could have gotten interesting. Same as finding a fly stuck under the BOV valve so it wouldn't seal.

    A pre breath of about 5 mins does two things 1) ensures the unit can hold ppo2, positive and negative pressures (no leaks) and to get the lime working.

    Most issues occur on the surface. But issue do a raise at depth. Solinoid staying open, Scrubber break through. Flooding. Cell failure. Golden rule know your ppo2 and flush With dil.

    BK
     

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