Accident in Finland

[paulraymaekers]

Some great points being made here. Doesnt it just prove that each unit is different so therefore get unit specific training and that its not really about how you do it, but more about making sure you do it in the first place. consistently and routinely!

eactly!

if anyone takes care to have a look at our check-list, where it clearly says, before jumping in, pen O2, switch on shearwater, setpoint 0.7, hear the solenoid fire and raise the PPO2 to 0.7, add manually etc etc

do NOT modify your unit, unless factory approved: an instructor that advises users to modify their unit is not really appreciated by the manufacturers group.

paul

 

[Igor]

"rEvo guys: You cannot isolate your ADV (unless you talk to me and I talk you thru a workaround, which can be done with some Omniswivel parts)). For that reason I no longer support their use with hypoxic mix as-sold.

A freeflowing ADV near the surface should not be a path to death. "

I am not a REVO diver but it seems a bit harsh to rule out a complete brand of rebreather just because you can not isolate the ADV. A very simple approach is simply to use a OC travel gas and infact some argue that this might be the most straight forward approach to mitigate the risk of a free flowing ADV. There are other ways around the problem in my opinion.

Ginaameri pointed out in an earlier post that what if you forget to isolate your ADV with the flow stop? That could potentially be even worse as then you go ahead diving assuming your ADV is turned off. The answer is probably "then you just turn it off". Sure i can buy that and i almost can´t imagine a situation where you would not notice the ADV fired but i guess there could be ? If you turn the argument around then you might as well dive the unit as a O2 rebreather above 6m or whatever your hypoxic diluent depth is. If the ADV free flows you turn off the valve. You would lose the wing but is that a big deal if you are in a drysuit? I am not saying an ADV flow stop is a bad idea. I am just trying to point out that there are several approaches to the problem. Another 2 cents.

 

[gianaameri]

"rEvo guys: You cannot isolate your ADV (unless you talk to me and I talk you thru a workaround, which can be done with some Omniswivel parts)). For that reason I no longer support their use with hypoxic mix as-sold.

A freeflowing ADV near the surface should not be a path to death. "

I am not a REVO diver but it seems a bit harsh to rule out a complete brand of rebreather just because you can not isolate the ADV. A very simple approach is simply to use a OC travel gas and infact some argue that this might be the most straight forward approach to mitigate the risk of a free flowing ADV. There are other ways around the problem in my opinion. Someone pointed out in an earlier post that what if you forget to isolate your ADV with the flow stop? That could potentially be even worse as then you go ahead diving assuming your ADV is turned off. Another 2 cents.

ADV flow-stop open or closed (deliberately or in error), shallower than 6 meters (to include on the surface) I do not let the rebreather control the O2. I control it by making sure the counter-lungs are full of 100% O2.

The ADV though can free-flow at any time... so I do not understand how on the rEVO you can deal with an ADV free-flow (unless there is a QC on the ADV feed which you can disconnect, but then especially if the ADV has failed you could flood the loop disconnecting the QC).

On this one I think Dave is right to suggest adding a flow-stop to the rEVO ADV at minimum to isolate the ADV in case of free-flow, or as Dave teaches to reduce the risk of an hypoxic loop (for those who like to manage the ADV flow-stop as Dave teaches).

 

[Mr Walker]

The ADV though can free-flow at any time...

Really? Any ADV? Even if it's an upstream?

/nils

 

[gianaameri]

Really? Any ADV? Even if it's an upstream?

/nils

Well, if an ADV o-ring/seat fails, then you have a free-flow.

Is the rEVO ADV (only saw it once at LIDS) upstream and, in any event, it cannot free-flow?

The Meg ADV can free-flow and it is a plunger type (not derived from an OC 2nd stage upstream or downstream).

 

[Igor]

The following is just a segue, taken from the above but not an observation on the JJ, but merely on diver habit patterns: I have spent the last three days with Leon, and we were discussing hybrids, etc.. and his view on them (which I share) is that they actually reduce safety: Divers get used to tuning theor 02 OFF, which allows them a chance to forget to turn it back ON.


Dave

.

Very good point regarding HCCR.

 

[gianaameri]

[QUOTE
The following is just a segue, taken from the above but not an observation on the JJ, but merely on diver habit patterns: I have spent the last three days with Leon, and we were discussing hybrids, etc.. and his view on them (which I share) is that they actually reduce safety: Divers get used to tuning theor 02 OFF, which allows them a chance to forget to turn it back ON.


Dave

.

Very good point regarding HCCR.

Not really.

Hybrids increase safety provided each system (the eCCR and the mCCR feeds) are totally independent one from the other (two separate O2 bottles...).

In my hybrid I open both O2 cylinders valves before donning the rebreather, and they stay open till after I remove the rebreather.

There is a locking QC which feeds out of the Pelagian Needle Valve into the exhale counterlung which I can connect or disconnect from the counterlung (as needed), and it is easy to verify it is is connected or disconnected.

I do not start the dive with the mCCR QC feed disconnected (as a rule, insofar I cannot inject O2 with the QC disconnected and I would note immediately if it is disconnected since I flood the loop with O2 before submerging).

If I do something wrong, I would have to do something wrong on both the mCCR and the eCCR (i.e. a single functioning system is capable of supporting life).

I suspect a similar system with the protocol of always injecting O2 manually shallower than 6 meters including at the surface could have reduced the risk (although not entirely eliminate it) of this and similar fatalities.

What I was taught in Mod 1. is proving again and again to be inadequate as a system and protocol.

 

[Igor]

Not really.

Hybrids increase safety provided each system (the eCCR and the mCCR feeds) are totally independent one from the other (two separate O2 bottles...).

In my hybrid I open both O2 cylinders valves before donning the rebreather, and they stay open till after I remove the rebreather.

There is a locking QC which feeds out of the Pelagian Needle Valve into the exhale counterlung which I can connect or disconnect from the counterlung (as needed), and it is easy to verify it is is connected or disconnected.

I do not start the dive with the mCCR QC feed disconnected (as a rule, insofar I cannot inject O2 with the QC disconnected and I would note immediately if it is disconnected since I flood the loop with O2 before submerging).

If I do something wrong, I would have to do something wrong on both the mCCR and the eCCR (i.e. a single functioning system is capable of supporting life).

I suspect a similar system with the protocol of always injecting O2 manually shallower than 6 meters including at the surface could have reduced the risk (although not entirely eliminate it) of this and similar fatalities.

What I was taught in Mod 1. is proving again and again to be inadequate as a system and protocol.

Ok. But most HCCR divers are only diving with one 02 bottle right? But i guess if you can QC out the needle valve instead of turning off the o2 cylinder it should be alright in this respect.

 

[gianaameri]

Ok. But most HCCR divers are only diving with one 02 bottle right? But i guess if you can QC out the needle valve instead of turning off the o2 cylinder it should be alright in this respect.

You are reducing risk only when you have two totally independent systems.

The way "most" people dive hCCR as you describe, they are adding complexity and failure points, and not necessarily reducing risk, because the system is just one bigger single failure point.

Same thing about sharing O2 Sensors piggy-backing them over two electronics. Sharing 3 or 6 or 12... O2 Sensors does not necessarily reduce risk.

Totally independent systems reduce risk because one cannot interfere with the other and each is capable of being life-support independent of the other.

The QC systems for the mCCR part of my rebreather I quite enjoy it. Easy to access, manage, and verify (and the 1st stage is less likely to inadvertently suffer water ingress).

 

[swadiver]

Very good point regarding HCCR.

ahhh.......................bullshit

 

[Dave Sutton]

I am not a REVO diver but it seems a bit harsh to rule out a complete brand of rebreather just because you can not isolate the ADV..

I didn't rule it out. I said that if you want to dive hypoxoc gas on one that you need to manage the system so that there is no possibility of having that gas on the ADV where it would cause hypoxia if there is a freeflow. There are at least two ways of doing it with gas on the chassis. One is to use the cylinder valve. The other is a simple Omnisvivel setup that can be added.


Dave

.

 

[Dave Sutton]

With that procedure, it would be very easy to forget (Human Factor) the ADV in the "wrong" position, and it is downhill (bad) from there because you would assume it is isolated, when it is not.

Gian.. Were you really ever trained on a Meg?

There is one procedure that is supported by the manufacturer, and I have recited it. Why is it that you want to propose EVERYTHING ought to be the opposite of techniques and practices that are widespread, proven to work, robust, and trained (at least) by every Meg instructor? You continue to recite such utter nonsense that it's almost a full time job countering your... "methods".

Hybrids increase safety provided each system (the eCCR and the mCCR feeds) are totally independent one from the other (two separate O2 bottles...)..

There is absolutely no evidence to support this.




Dave

.

 

[PeterN]

I didn't rule it out. I said that if you want to dive hypoxoc gas on one that you need to manage the system so that there is no possibility of having that gas on the ADV where it would cause hypoxia if there is a freeflow. There are at least two ways of doing it with gas on the chassis. One is to use the cylinder valve. The other is a simple Omnisvivel setup that can be added.


Dave

.

Or you can do what a lot of rEvo divers do when they become frustated with adjusting the adv, they disable it!

Peter

 

[Dave Sutton]

Or you can do what a lot of rEvo divers do when they become frustated with adjusting the adv, they disable it!

Peter

That's not right either though... although I can see why they would do it.

The way I set up my own rEvo for hypoxic mix was to remove the short feed line that runs to the chassis and replaced it with a longer hose that goes over my shoulder, to a slider, then to a 180 degree turn fitting, to another hose that goes back paralleled to the first hose and back to the original rig chassis entry point. Silder on = gas to rig, slider off = gas off to rig. Wings are still powered by the first stage. Yes you lose the chassis manual add valve when you the slider is closed. Big deal... when it's closed it's closed because the diluent = dead diver.

I only added and used it when using 10/70. I used the same procedure as is taught as the standard for the Meg for all dives: 0.7 on deck held by controller for 5 minutes, isolator is off, jump. Lung volume supplemented with 02 manual add valve to 6 meters, isolator open, bubble check done, and descend. At bottom slider off. On back again if needed, off again when not needed. No way to jump with 02 off, an unpacked scrubber, or die due to hypoxia after a freeflowing ADV if you follow this simple procedure. If this were done religiously by everyone, it would reduce accident rates significantly. I spent the last three days standing 8 hours a day with Leon, much of it talking about whatever we felt like, and we discussed this at length. He agrees, and it's the only standard procedure that he accepts for the Meg in training. I agree as well. It's simple, robust, catches many errors, and works. I can name several divers who would be alive today if they had followed it.




Dave


.

 

[GLOC]

Guys, can we keep the discussions relevant to this incident and possible mitigations given the scant knowledge available, rather than have a willy waving competition...

Thanks

 

[gianaameri]

Why is it that you want to propose EVERYTHING ought to be the opposite of techniques and practices that are widespread, proven to work, robust, and trained (at least) by every Meg instructor?

Dave

.

Dave,

when you have people (some with 1000s of hours of diving experience) dying in 20 meters of water, 6 meters of water (double fatality in Trieste), and now on the surface - that tells me the Gurus generally got it wrong.

So, my opinion is that for me I have to do things differently than mainstream thinking.

You do the same when you modify manufacturer equipment (putting a BOV on a rEVO or modifying the rEVO ADV feed system... or advise not to dive such/some equipment with hypoxic mixes without YOUR modifications).

Many things you say, you are probably right.

As to the Meg ADV (and the rEVO ADV and other ADVs...), there is not a Manufacturer or a Training Agency manual which tells you how to operate the ADV and in what sequence (i.e. in the manner you suggest).

It would be useful if each manufacturer for each unit would write a clear instruction manual describing exactly the diving procedure for the unit's ADV (this way we can read it directly from the manual rather than debate it on an internet forum).

Here it looks like a JJ fatality.

So, what is the ADV management procedure for the JJ (anybody)?

 

[wrench]

^^^^^
Statement from JJ-CCR manual(section 5.4 (ADV)) : "Do not install an inline shutoff valve under any circumstances" (downloadable from JJ-CCR website DOWNLOADS - JJ-CCR) i guess this might be a CE thing.

During my JJ course(a two day crossover course from meg) i was told not to use the ADV shutoff valve which was installed on the unit that i was diving(it was not my unit)

Asking not to shutoff a soft ADV(JJ ADV is quite soft) which is connected to a hypoxic mix, is some thing better be discussed with IART and the manufacturer.

 

[wrench]

^^
Are you sure there is an ADV shutoff on Inspo CE stock model? or it is jut the UK version.
CE is the only reason that i can think of, why they specifically ask the diver not to install an ADV shutoff(in red font)
I am not insisting that i am right, It's just a guess.

 

[blackman]

Another reason could be the way the ADV is built.
Using a shutoff introduces a hammer effect when switching back on. Can the ADV deal with that or not?
I don't know at all the build of the ADV but this could be a reason.....

 

[gianaameri]

^^
Are you sure there is an ADV shutoff on Inspo CE stock model? or it is jut the UK version.
CE is the only reason that i can think of, why they specifically ask the diver not to install an ADV shutoff(in red font)
I am not insisting that i am right, It's just a guess.

My Evolution had a factory-fitted ADV shut-off valve and the unit was marked EN14143:2003.

I was not taught any particular procedure during my courses up to and including MOD. 3 (i.e. other than leave the ADV open and make sure it is open at the start of the dive).

I was warned by the Instructor that with Trimix (thinner gases) the ADV can leak, and advised by my instructor to remove altogether the APD Buddy Inflator (not the ADV flow-stop) because with Trimix gases the APD Buddy Inflator would definitely leak, at some point, sooner or later, and empty my little 2 liter Diluent inboard very quickly.

I witnessed this happen to a diver diving with me as we were descending and when we got to the bottom he showed me his near empty inboard Diluent tank SPG... and I had a good laugh looking at his face saying:

"What am I going to do now?"

He did not notice and would not notice because the APD Buddy Inflator hangs on a long BCD hose and it is out-of sight down the side of the diver... so he descended streaming bubbles behind.

His Alu80 Trimix bail-out came in handy and I indicated to him to plug-it in the MAV showing and handing him the LP hose and QC from the Alu80.

Bottom line, some ADVs leak with Trimix and the same ADVs do not leak with Air.

Dave is right to suggest the use of a flow-stop on the ADV.

I had a very good instructor and lucky is the student who has Dave as an instructor (even though some instructors do not always follow manufacturer procedures).