How Did You Learn About Current-Limited 02 Cells?

Mdemon

Came across it first in a long and convoluted ramble from AM.

Picked up the testing techniques from discussions led by DrMike, (who is also responsible for my current state of poverty...namely getting Rebreather, BOV, etc etc

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"Once the agenda-monkeys and perfect-worlders have moved on, perhaps we can do some diving?"

Janos

I learnt about it on Rebreather World. But then I was reading RBW before I did my MOD 1. It was covered throroughly on my MOD 1 though.

Janos

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ccr_ada

then AM's rant on the inspo list

that may of saved my life as i had a couple of current limited cells at the time

thanks fool!

ccr_ada

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SteveL

have to say that current limited cells nearly killed me early this year - tends to focus ones attention somewhat

In addition I think that curent training is woefull as to the dangers of CL cells - they talk about it but thats it - it is a very real problem and occurs more often than you think. AND without warning

I have new cells in june this year one of them gave up completely a few weeks ago with no warning whatso ever - due to my earlier experiences I am now much more wary and picked it up befor it became a problem - but many would not - due to training regimes being focused on the deadly but unlikely failures .......

wher alot of emphasis needs to be placed on the perception of less deadly but certainly more common senarios - which ultimatly are ,leathal

One bottle of wine later - hope this makes sense???


Steve L

nmanfield

I must say that Rebreather World , my instructor and reading up in text books helped me. As an ex inspiration diver i used to dil flush to check. Howver, now diving a Meg and i now read that this will not work with the megs 2 point (air and 02) calibration. Instead I now check Mv measurements. i take an Air Mv reading, multiply by the fO2 and multiply by 4.78. the value should be within a 1.25 mV (2%) linearity error for cells reading 13Mv in air. after this close o2 cyliner valve and DSV record po2 for each cell wait 20 mins. If po2 readings drop off rapidly then cells are coming / come! to the end of their life - but this doesn't mean they are necessarily going to be linear at higher PO2

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delidiver

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Mark Chase

On the inspo list thanks to Ann Marie

This was long before I did my CCR training but it wasn't covered in any detail on Mod1 or Mod2

It was more a case of "if theres a cell error" but it was like a cell error would set off a buzzer or something.

I was at first, convinced that cell errors only happened to people who didn't change their cells every 12 months. I was going to change my cells every six months just to make sure but then i had two brand new cells fail (dispie AP's insistence they were just fine) and i realized it was pointless.

I ended up do in a dive on two month old cells which worked perfectly. My brand new ones wouldn't reach 1.6 even on pure 02 at 10m.

ATB

Mark Chase

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pchanning

There was some mad bird harping on in the Inspiration list years ago. Can't think who it was now. Fair play to her though, she managed to change certain training literature IIRC.

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Cheers
Paul

The key to enlightenment... is survival.

AM

Thanks for that Paul haha I don't deny being mad but I have no feathers LOL

Nmanfield talks about looking at mV output etc. Can I humbly point out that millivolt output can actually INCREASE as current capability drops off. This renders the cell easily able to pass the requisite calibration routine in certain rebreathers even though the cell is not fit for diving.

Furthermore, the configuration management anomalies that exist of over many different releases of software on certain units, mean that cells within different mV ranges will calibrate!!

I would not recommend using millivolt output even with any calculation on top as a valid indicator of current producing capability. Blowing the cells up to 1.6 in water really can't be substituted for anything else and is the best way to test the cells as you are about to dive them.

There is of course, the smaller test of blowing the bags up to 1.0 once a week and watching for drift in addition. If the cells can't hold 1.0 they certainly won't hold 1.3!

Regards

AnneMarie

PS I think my very early posts on here do disseminate the topic of current limiting in some detail.

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