mCCR Training Regarding Total Electronic Failures

Garth

Garth

Tunnel Vision
Are people getting trained to deal with a total electronic failure with an mCCR with the possibility of staying on the loop?

This sounds rather hard core for me but I heard it still goes on and wonder what others thought about this. I'm not trying to be controversial here by bringing this up but I do admit there will probably will be strong opinions potentially on both sides.

I don't want to just know eCCR or just mCCR so whenever I meet someone diving rebreathers I always try to ask them what type of training they got on their unit? I think this could lead to healthy discussion with the intent to learn more. I want to be a thinking diver and right now I just don't know enough about everything.

Oh, lastly the environment in which the training occurred was in a cave.

Thanks,
Garth
 
I was trained to run the unit for SCR in this eventuality in my MOD1 a few months ago, I believe it's still pretty standard training.

Pretty simple, though: switch the gas I'm not using off (in case of stuck open O2 solenoid, for example), throw away every 5th breath below 10m or 3rd breath above it, maintain minimum loop with top ups of diluent below 6m or oxygen above it.

Edit: sorry, just re-read your bit about not caring about eCCR. But with the electronics packed in how is it different? If you can't monitor your loop oxygen, surely the only safe way to "know your PPO2" is to disable the bypass and proceed as above?
 
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no training other than scr , (EDIT i do have rebreather training ) wrecks inside and out not caves ,

so i just went and got a shearwater its running off the 3 cell,s on my unit , main unit hand sets and bat,s can crap out , i can still run unit with SW and MAV ,S

Id not go as far as saying you need training ,, its called backup plus (the plus is i get real time deco and a 2nd computer )


ps
stuck open O2 solenoid

turn off inboard 3l , feed in o2 from back up 2l off board o2 v MAV ,, backup plus (i get all most 5l of o2 to play with if iv got to bail out ) and it trims out my unit as iv a 2l suit feed on the other side . my buddy has the same set up so all most 10l or o2 ,
just the job for a bit of OC deco , when your units full of water ,

maybe when i do mod2 ill know better , :shrug:
 
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Mr fish said:
no training other than scr ,

so i just went and got a shearwater its running off the 3 cell,s on my unit , main unit hand sets and bat,s can crap out , i can still run unit with SW and MAV ,S

Id not go as far as saying you need training ,,
Click to expand...

Although you and many others might be able to dive a RB successfully without official training, please remember that these forums or open to the general public and some newbie might learn the fatal way that there is something that they needed to know after it is too late for them.
 
DSix36 said:
Although you and many others might be able to dive a RB successfully without official training, please remember that these forums or open to the general public and some newbie might learn the fatal way that there is something that they needed to know after it is too late for them.
Click to expand...


im still not going to say you need training to use a shearwater computer , as back up for when a unit craps out, or as a back up computer ,

if they want to dive to depth or use a breather, well by all means go do some training , i have a mod 8 , its one of them internet learning courses
18 quid . 2hr a week 6 weeks in all lol

may do the deeparmchair guru next its 18 weeks tho , and 30 quid .:hehehm:
 
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Define total electronic failure.
On my rEvo rMS, 3 cells are read by the Predator, another two by two Dreams (one each). If the predator fails (battery? Cracked screen? Severed cable?), I still can check my pO2 on the two remaining Dreams, and there is no reason really for me to bailout (although I probably would. At the time, I bought into my instructor's argument "if you travel and your SW dies, you still can dive").
If I lost ALL cells, I would get worried about the integrity of the loop and probably bailout, just to stay on the safe side.
A failed solenoid doesn't belong to that scenario (it's not a "total electronic failure").
SCR was taught to me as a remediation for lost O2 and specifically only to reach an ascent line IN CASE I RAN INTO THE RISK TO BE SHORT ON BAILOUT and not willing to make a blue water ascent.
I am not sure what you are expecting for answers? Memory gets fuzzy after a few months...
Oh yeah, I am still limited to no deco air diluent :-)
 
^^ a nice set of redundancy. Biggest problem likely to can a dive is that, after renewing all those damned sensors, I couldn't afford sorb. :P
 
uwxplorer said:
Define total electronic failure.
On my rEvo rMS, 3 cells are read by the Predator, another two by two Dreams (one each). If the predator fails (battery? Cracked screen? Severed cable?), I still can check my pO2 on the two remaining Dreams, and there is no reason really for me to bailout (although I probably would. At the time, I bought into my instructor's argument "if you travel and your SW dies, you still can dive").
If I lost ALL cells, I would get worried about the integrity of the loop and probably bailout, just to stay on the safe side.
A failed solenoid doesn't belong to that scenario (it's not a "total electronic failure").
SCR was taught to me as a remediation for lost O2 and specifically only to reach an ascent line IN CASE I RAN INTO THE RISK TO BE SHORT ON BAILOUT and not willing to make a blue water ascent.
I am not sure what you are expecting for answers? Memory gets fuzzy after a few months...
Oh yeah, I am still limited to no deco air diluent :-)
Click to expand...

SCR , sounds just about the same as my training , MOD1 no coming up using scr back to shot if you must then bail out.
mod1 is a bail out course ,

mod 3 lets the blind rat run up the pipe , put even then its not blind and it not all the way up the pipe ,
 
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Mr fish said:
im still not going to say you need training to use a shearwater computer , as back up for when a unit craps out, or a back up computer ,


if they want to dive to depth or use a breather, well by all means go do some training , i have a mod 8 , its one of them internet learning courses
18 quid . 2hr a week 6 weeks in all lol

may do the deeparmchair guru next its 18 weeks tho , and 30 quid .:hehehm:
Click to expand...

Sorry for the confusion. I read your post to mean that you did not think that training was necessary for SCR mode rather than your intended meaning of SW usage.
 
Captain Starfish said:
I was trained to run the unit for SCR in this eventuality in my MOD1 a few months ago, I believe it's still pretty standard training.

Pretty simple, though: switch the gas I'm not using off (in case of stuck open O2 solenoid, for example), throw away every 5th breath below 10m or 3rd breath above it, maintain minimum loop with top ups of diluent below 6m or oxygen above it.

Edit: sorry, just re-read your bit about not caring about eCCR. But with the electronics packed in how is it different? If you can't monitor your loop oxygen, surely the only safe way to "know your PPO2" is to disable the bypass and proceed as above?
Click to expand...

iv never heard of 5 to 1 being used at mod1 depths , 3 to 1 yes , id not want that to be going round the interweb 5 to 1 and coming up . with a ppo2 drop . o2 off and air dill .

and you even got some oxygen foreplay at 6m thats a step in the right direction .

dsix36 were,s dsix36
 
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DSix36 said:
Sorry for the confusion. I read your post to mean that you did not think that training was necessary for SCR mode rather than your intended meaning of SW usage.
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yes i reread my post , and put in a small edit ,
no problem m8.

i can be a tosser some times ,, lol well most of the time, if the truth be known ,
 
3:1 is what I was taught too.
But now, I dive with an AL80 30% Nitrox as bailout (to get used to the size for the future), so bailout is probably going to be my option no matter what the current situation is, unless I have planned to practice SCR with my buddy nearby.
 
Ok. I know how to use SCR by performing diluent flushes and for eCCR is about every 3rd breathe.

I think the conversation i had with one mCCR diver included something that didn't require SCR or SCR was not completed. Is there any other way for an mCCR diver to exit without using SCR (diluent flushes)?

Defined total electronic failure... Blacked out gauges... I.e no readings of PPO2... No depth, no nothing.


Let me also state that I know what I was trained on the hammerhead to do and it would include either bailout or SCR but this is something different.

Do people know how to maintain PPO2 on their mCCR without actually having to look at their gauges... Under normal operation they would of course be monitoring PPO2 but I'm simply asking if anyone was trained on their mCCR to control PPO2 without the readings to simulate the worst failure possible....?


Garth


Garth
 
One thing I have had smacked home from forumland (here or that other one, can't remember which) was that it's a really good idea to practice that SCR drill when your PPO2 meters are working so you can get a decent idea of what's going on.

How much is your PPO2 dropping per breath? How many breaths can you pull out of the loop before that PPO2 drops to undesirable levels at whatever depths? How well can you keep count?

I've heard guys running 3 breaths shallow, 5 breaths 10-30m and 10 breaths deeper than that, but I know I'd lose count too easily to keep track of all that - especially in what I'd assume to be a high stress, task loaded aborted dive ascent.
 
Garth, perhaps you are referring to monitoring your PO2 by paying to attention to your loop volume. If you were to maintain a constant depth and lost all electronics, and could not bailout for one reason or another, it is possible to somewhat estimate when to add O2 by monitoring your loop volume. As your counter lungs start to decrease in volume, you know that you have metabolized O2 and it is time to add O2. It takes quite a bit of practice to get the hang of it and really only works at a constant depth for obvious reasons. I don't teach this skill until the more advanced courses because most newbie CCR divers don't have the fundamental skills down good enough to recognize when to add the O2. If you are running your unit manually, most people will naturally start to do it anyway after a few hours on your unit. Of course, I am not suggesting that this is something for people to do in lieu of using electronics. Its simply another do or die skill that could be used as a last resort if bailout is not available and SCR is not appropriate for whatever reason. If your unit is an mCCR, it becomes a little trickier due to the constant flow valve, but ultimately, the same principal works, its just a matter of learning how much to add based upon loss of loop volume due to metabolism. Again, this is an advanced skill and should be practiced initially with your instructor and while monitoring your electronics.
 
Garth
I imagine what Randy said is what you were looking for. It really becomes second nature when to add gas. But I typically have a HUD and a Handset telling me why my perceived decrease in loop volume is also telling me.

If you really new what your current O2 metabolism rate was and new what the flow rate was on your mCCRs CMF orfice you could sort of guess what you PO2 is without electronics. However the number 1 rule in CCR diving whether it is eCCR or mCCR is always know your PO2. This is done either with a PO2 display or with SCR.


Sent from my iPhone using Tapatalk
 
Garth said:
Defined total electronic failure... Blacked out gauges... I.e no readings of PPO2... No depth, no nothing.
Click to expand...

Some of us still have non-electronic gauges...
Note to self: get a non-digital depth gauge as a backup.
But regardless, that's an interesting survival scenario you are bringing up.
I'd be curious to learn whether Randy's recipe works for BMCL though, or is it just a matter of avoiding to trigger the ADV and press the O2 MAV instead?
 
uwxplorer said:
Some of us still have non-electronic gauges...
Note to self: get a non-digital depth gauge as a backup.
But regardless, that's an interesting survival scenario you are bringing up.
I'd be curious to learn whether Randy's recipe works for BMCL though, or is it just a matter of avoiding to trigger the ADV and press the O2 MAV instead?
Click to expand...

You are correct there are analog PO2 displays but these could fail just as electronic PO2 displays could.

SCR is typically used for two main reasons:
1) loss of O2 SCR can be used to extend the life of your diluent or bail out tanks
2) loss of PO2 display. For this you would use SCR on diluent or a bail out gas Until you are above 6 m or 20 feet then you could just use your rebreather as an oxygen rebreather.

This can be done with back mount counterlungs. For most agencies it is a required skill to learn.


Sent from my iPhone using Tapatalk
 
uwxplorer said:
Some of us still have non-electronic gauges...
Note to self: get a non-digital depth gauge as a backup.
But regardless, that's an interesting survival scenario you are bringing up.
I'd be curious to learn whether Randy's recipe works for BMCL though, or is it just a matter of avoiding to trigger the ADV and press the O2 MAV instead?
Click to expand...
I just realized you were probably referring to the noticing the loop volume decrease as you metabolize O2 with BMCLs.

You are correct it is simply a matter of either isolating the ADV if your unit lets you or avoiding the ADV firing and adding O2 to make up the gas you have metabolized.
 
WIth no PP02 display id bailout to OC and go home

That would be a zero stress situation so no elevated SAC so id have a big safety margin in my OC gas.

Only hapened once to me. Flooded a rEvo and it trashed all three cells. No amount of redundent displays was going to help.

As above i bailed and ended the dive OC

SCR is nice to have in reserve but why would you need it if you planned adiquate bailout?

ATB

Mark
 
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