Minimising Rebreather Deaths / Fatalities

Ivon

Must spread some about a bit, one in the bag!

CharlieT

Stuart

Thank you for the article which I see has produced a lively discussion.

You should be complimented for taking into account the many concerns that have been expressed on Rebreather World recently about Rebreather deaths and doing something constructive about this.

Have lots of green.

Charlie

sensor330

Great article Stuart. Although I disagree with you on flying a ECCR manually. BTW if anyone is interested here is a poll the has to do with this point. http://www.rebreatherworld.com/gener...your-eccr.html

Scott

schford

Thanks for the feedback - let me explain a little bit more about why I put that in.

Firstly when examining all the Information I had on fatalities I was unable to discover a single one where the Rebreather was being flown manually.

Now what I think this means is that by flying a unit manually you are FORCED into checking your PPO2 very regularly. So you notice if something is wrong and take corrective action.

If you rely on the leccies to keep your PPO2 one might get complacent and not check them regularly enough to notice when something goes wrong.

If you are disciplined enough to check your PPO2 very regularly and make sure you notice things like a frozen display then it should be just as safe.

Unfortunatly evidence suggests that 100% of us do not check the PPO2 regularly enough perhaps because they have always worked for those hundreds of hours until they dont.

I think the act of flying the Rebreather manually forces you to be much more alert to your PPO2 and ensures you do not become complacent whilst still having the eCCR as a safety net.

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Mike

Anyway - I find it ludicrous that people dive an ECCR as a MCCR all the time. If you don't trust the electronics to maintain setpoint for you normally, then how the hell do you trust them as a parachute?
Either you kind of trust them (ie let them do their thing but watch them) or you don't - in which case there is no valid argument for saying;
"I don't trust my electronics to work normally, but I do trust them in an emergency when I've stuffed up and if they don't work I'll die"

Backup systems should be more reliable than primary systems.

Sure - fly manual from time to time to make sure you can do it. (Yep, I can read a guage and press a button every now and then - whoo hoo I'm a rebreather master ) But if you're going to dive an ECCR, why not use it?

If you want to fly manual, save a bunch of cash and get a MCCR.

Mike

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bletso

Personally, If one isn't comfortable diving CCR shallow, they shouldn't be taking it to depth. After all, you have to go and return through shallow depths to get deep.

I dive my MCCR all the time and at any depth. I have no misgivings what so ever taking it where ever. I dive OC only when I have to. i.e. teaching


Dale

01RMB

The trouble with running a ECCR as a MCCR is that the KISS valved units actually are designed to maintain a continuous level of O2 injection without any intervention. The danger for users manually flying their units with the assumption that when you get distracted the electronics will cut in - is if the setpoint controller does not work and you are not aware of it because you have not been making the unit electronically add O2 (eg if the batteries are too low to fire the solenoid but enough power to run the display) then there will not be ANY O2 injection when you need it.

Practicing manually controlling your PPO2 and continuously monitoring your PPO2 should not be any less safe than manually flying a ECCR.

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Rod

Gilles

Flying eCCR manually is not a 100% solution, but it adds significant incremental value for very little cost. By cost, I mean effort in learning and building technique and habit!

I will argue that it is worthwhile having eCCR, even if your technique is manual flight. I (amongst others) mistakenly applied the acronym mCCR to the technique of eCCR manual flight. eCCR with correct monitoring is safer and better than an mCCR because a functioning SP controller will maintain SP over a wider range of O2 consumption and should allow greater task loading (amongst other considerations)!

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Gilles
http://www.dirrebreather.com

silent running

Um yes, good obvious point Mike-you either trust the E or not, shouldn't matter whether primary or seconary. On top of that, I'm not only trusting my electronics, I'm trusting my ears, listening for the solenoid, it's frequency of firing and quality of the inject. When mine blocked up, I knew imediately. And I'm pretty sure the solenoids on all ECCRs are audible. If I heard the solenoid firing frequently, say at the bottom of a descent, I would know something was wrong and check the 2dry right away. And if you bother to check your 2 dry, you'll know if the Es are hanging or not. Do all HUDs flicker/pulse like the Prism? They ought to.

And so to the next question-how many ECCR controller have hung and which ones? And if they did, wouldn't the PO2 start dropping, not so life threatening as climbing. Who doesn't bother listening for the solenoid AND never checks their 2drys? A person who is too careless for CCR...

RonMicjan

Flying a rig manually helps keep the diver focused on the workings of the rig, watching po2, seeing the sensors respond during injection, etc. When the diver gets busy for a few minutes, the solenoid firing is a poke in the ribs to wake up and get focused again.

If you never run manual, its much easier to get complacent and let the unit run itself, so the diver is in la-la land, trusting the unit and when it quits, there is one extra layer of attention that is missing, IE: manual operation. This also prepares the diver for the time when the primary fails and solenoid operation quits, if you run manually a lot, then having the solenoid fail is no longer an OMG, its a minor inconvienence.

I generally hear my solenoid fire about 3-5 times during a dive, which means I neglected it for maybe 3 minutes at most, it takes a bit longer than that to get me hypoxic, unlike a K-CCR (kiss style) which can go a whole dive w/o becoming hypoxic due to the constant bleed. (if set up perfect) I thought about taking along a small o2 cylinder plumbed to the loop with an orfice, to have the best of both worlds. Would save batteries too.

Having cut my teeth on K-CCR (why not adopt K-CCR as the official term for leaky valve CC rebreathers?) I am used to keeping good track of displays, its the folks who just strap on the rig and swim merrily away who are going to get in trouble more often than the ones with a healthly dose of paranoia. Im guessing that these would be the folks who tend to neglect proper maintainence also.

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