Double Fatality in June 2014 (UK) - Inquest and Media Reports

[Mark Chase]

Guess I'm a bit lost.

So you guys would actually get in the water with a 4yo, 3yo, and 18month old cells in a 3 cell unit? Assuming they read 0.21 in ambient and hit 0.98+ with an O2 flush?

Of course not the chances of me missing a dive due to cell errors would be unacceptably high.

But if the question is, would putting thease cells in my unit kill me?

Absolutly not.

And thats the key issue here. We need to stop thinking of the old cells as a cuase of death and start thinking about cell monitoring (or lack of it) as the cause

If the thinking haveing read this thread is "I have new cells Ill be OK" then we have lerned nothing of value from this tragic loss of life.

ATB

Mark

 

[rjack]

Of course not the chances of me missing a dive due to cell errors would be unacceptably high.

But if the question is, would putting thease cells in my unit kill me?

Absolutly not.

And thats the key issue here. We need to stop thinking of the old cells as a cuase of death and start thinking about cell monitoring (or lack of it) as the cause

If the thinking haveing read this thread is "I have new cells Ill be OK" then we have lerned nothing of value from this tragic loss of life.

ATB

Mark

All the cell monitoring in the world isn't going to make a 3 or 4yo cell alive again.

Of all the toxing deaths I have heard about recently have been on cells way way older than 12-18 months. I know of zero fatalities on cells younger than 18months. My sample size is not that large and I may be getting the dates wrong so I'm willing to be corrected if you know of a tox event on <18 month old cells.

 

[Baron015]

Ditto... I'd imagine some divers confuse checking calibration with actually calibrating?
My Shearwater powered MCCR was only calibrated twice last year but I confirmed the calibration prior to every dive.

No I think some divers are confusing the training provided by agencies on behalf of the manufacturers, which says to calibrate each day/dive, with what a lot of divers on this internet advocate instead, which is to check calibration each dive and then not calibrate

(having shown the cells are within some range of expected values say 0.20 - 0.22 in air, and something between 0.94 - 1.00 after a O2 flush depending on how pure your O2 source was and how you were meant to know that in the first place eg membrane system on Windward in Bikini produced 90% O2).

Well what to do, follow the training or the Internet advice ? Isn't there a useful phrase or maxim to remember how to choose in these circumstances ?

(Actually I know some of these particular Internet divers in real life and would tend to give their views some weight, so this one is a real conundrum)

 

[ebt]

Its worth remembering that all calibration does is;

1. Check that the cells output is within the expected range
2. Apply a correction factor, so that when the adc output is computed the PO2 display is scaled to allow for movement within the acceptable range.

If you verify cal by an o2 flush and get a reasonable response, you've done the same as the calibration routine does. I guess maybe the poseidon or apoc controllers may do something different...... <shrugs>.

Ive seen guys calibrating between dives on the same day, which is a scary thing, that can lead to some very funky readings

 

[Baron015]

Ive seen guys calibrating between dives on the same day, which is a scary thing.

But I'm pretty sure some Mod 1 courses say to do this.

I guess some condensation on the cell face may affect the mV reading, in the same ppO2 as earlier. So your cell reading may look like drift on a later dive, even tho the real ppO2 has not changed, a new calibration can fix this / make it worse (delete as applicable).

 

[emmbee]

Its worth remembering that all calibration does is;

1. Check that the cells output is within the expected range
2. Apply a correction factor, so that when the adc output is computed the PO2 display is scaled to allow for movement within the acceptable range.

If you verify cal by an o2 flush and get a reasonable response, you've done the same as the calibration routine does. I guess maybe the poseidon or apoc controllers may do something different...... <shrugs>.

Ive seen guys calibrating between dives on the same day, which is a scary thing, that can lead to some very funky readings

Actually, you haven't. O2 calibration will fire the solenoid, a lot, so it gives the electronics a chance to complain about the battery. The real real question, if "you've done the same", is why not do it?

I don't usually calibrate between dives on the same day, because I usually do only one dive, but I do calibrate every diving day, before the boat leaves. I get 50-51mV, 52 if the weather is brilliant (read: anticyclone), 49 (or possibly 48) if the weather is crap (and/or I'm at altitude - for some meaning of "altitude"). If it goes wrong I can fix it before we hit 2m swells, and if it goes reeaaly wrong I get the option of not spending 10 hours at sea (and going back to bed ).

What's the problem?

Matthieu

 

[ebt]

Fair point about the battery..... easy to forget you fancy tarts with your solenoids Mind you I'd expect to pick that up on the pre-breathe.

before this becomes yet another internet 'argument', the point being made is that there are some good reasons not to calibrate every dive (namely that you want to see when your cells start reducing their output). But as ever, its good to hear both viewpoints and form your own opinion.....

 

[emmbee]

Fair point about the battery..... easy to forget you fancy tarts with your solenoids Mind you I'd expect to pick that up on the pre-breathe.

before this becomes yet another internet 'argument', the point being made is that there are some good reasons not to calibrate every dive (namely that you want to see when your cells start reducing their output).

True, easier to fix before you hit the waves tho

I do get the point, but you'd get the same by simply reading the cell output - shearwaters do that. Like I said, I know what I want to see. As a bonus I can see which cells are faster and slower in replicable conditions - and it's not necessarily the newest and oldest.

Cheers,

Matthieu

 

[rjack]

Fair point about the battery..... easy to forget you fancy tarts with your solenoids Mind you I'd expect to pick that up on the pre-breathe.

before this becomes yet another internet 'argument', the point being made is that there are some good reasons not to calibrate every dive (namely that you want to see when your cells start reducing their output). But as ever, its good to hear both viewpoints and form your own opinion.....

But they typically become non-linear at 1.2 to 1.4 before they become non-linear at 1.0.

Are your writing down your 100% O2 millivolts at every check? I do, but only because I calibrate before each diving weekend. I don't calibrate between dives on the same day or between mostly consecutive days. If I go 2 weeks without diving I would just recalibrate, uses almost no O2 and I track cell health over time looking at the calibrated mV in 100% on my checklists (which live in a 3 ring binder).

 

[matt]

..

 

[Vanny]

Am I missing something. Inspo manual , training and handset all advocate calibration at least before dive and again if more than 3 hours elapses between dives. Are you suggesting people don't do this/ignore this or do other units require less calibration than the inspo?

 

[ebt]

Nah, if we're 'suggesting' people do anything, its follow to the letter the instructions from their training & unit manuals, since that caters for any and all variations (altitude diving, big weather variations etc).

We're just discussing how calibration works, what it does and the pros/cons of interdive calibration.

I'll flag this up to the mods for a split though, I think we've derailed the original thread and devalued it a bit.

 

[rjack]

Nah, if we're 'suggesting' people do anything, its follow to the letter the instructions from their training & unit manuals, since that caters for any and all variations (altitude diving, big weather variations etc).

We're just discussing how calibration works, what it does and the pros/cons of interdive calibration.

I'll flag this up to the mods for a split though, I think we've derailed the original thread and devalued it a bit.

Its a bit hard to believe a 4yo cell could be calibrated at all. All of mine die way before 4 yrs. So the first fatality was (likely) diving an uncalibrated Meg. I'd like to know for sure, but there might be no paper trail as well.

 

[ebt]

I think the debate has moved on...... we have parrallel tracks running;

1. is a commentary/discussion on calibration
2. is a discussion on the original incident and age of cells
3. is a discussion of the other aspects of the incident.

they are getting blurred.....

 

[Mark Chase]

Am I missing something. Inspo manual , training and handset all advocate calibration at least before dive and again if more than 3 hours elapses between dives. Are you suggesting people don't do this/ignore this or do other units require less calibration than the inspo?

No it's just that info you were given is bullshit:banana1:


Either that or the Inspo is so crap it cant hold calibration for longer than the average dive time

 

[Mark Chase]

All the cell monitoring in the world isn't going to make a 3 or 4yo cell alive again.

Of all the toxing deaths I have heard about recently have been on cells way way older than 12-18 months. I know of zero fatalities on cells younger than 18months. My sample size is not that large and I may be getting the dates wrong so I'm willing to be corrected if you know of a tox event on <18 month old cells.

And a failed brand new cell is just as dangerous (infact probably a lot more so as your less likley to think its comming) than a failed old cell

The monitoring for a new cell should be just as vigulent as the monitoring for an old cell

QED the whole age of cell issue is irelevent to the outcome


The relevance of your second comment is probably more to do with the attitude of the diver than the cell. Complacent about cells...complacent about monitoring cells

 

[matt]

I think the debate has moved on...... we have parrallel tracks running;

1. is a commentary/discussion on calibration
2. is a discussion on the original incident and age of cells
3. is a discussion of the other aspects of the incident.

they are getting blurred.....

Where's Dave when you need him ;-)

 

[matt]

no it's just that info you were given is bullshit:banana1:


Either that or the inspo is so crap it cant hold calibration for longer than the average dive time

lol.

 

[matt]

And a failed brand new cell is just as dangerous (infact probably a lot more so as your less likley to think its comming) than a failed old cell

The monitoring for a new cell should be just as vigulent as the monitoring for an old cell

QED the whole age of cell issue is irelevent to the outcome


The relevance of your second comment is probably more to do with the attitude of the diver than the cell. Complacent about cells...complacent about monitoring cells

How long is a new-cell a new-cell, when does it just become a cell?

 

[taliena]

The amazing thing to me is that there are still several members on this forum that openly admit to diving O2 cells well past their expiration date and do so as though they are wearing a badge of honor!

I bought new cells a few weeks ago. production date 10-2014. New cells. The seller, said don't worry, you will get 12 months warranty. So I dive now in the dangerous months after october to next years march? I have replaced the cells like adviced after 12 months of use, so 13 months after production.