WARNING dont order cells from AP just yet

AD_ward9

You don't understand: if your cells are old, you must be an idiot who went diving with old cells . There will be so many experts who will say that ... you will wonder how come so many famous people never took any interest in you when you were alive but could give opinions when you are gone and if you think this email thread will help you, then you may have a little surprise coming ... Bottom line is if your cells are not good, don't go diving with them. Diving with old cells, is a nice plan to meet you know who

I can tell you one thing for sure: the cell clock does NOT run from date of sale. You see, cells are not really very clever. They have no microcircuits in them or brain cells. They do not know when they are bought or sold.

The ageing process in the cells that you refer to are not even very sure if they are in oxygen: if you take one apart, look at the gold plated cathode and see how much black it has on it - it should have none, ever, but it does, and over time it gets more, until the cell does not work. This process of organic contamination inside the cell reduces life just as much as does consumption of the anode.

The problem of new cells going down very early, is why many divers do not replace a good cell until it fails. The risk from new ones is sometimes quite high.

Some interesting results I can share. We did not do a 7 year O2 cell study for amusement. What we got out of it is a method of knowing when a cell is or is not working, as well as better cells. The DL eCCRs know that out of 8 cells only 1 is working, and we allow dives to proceed with 2 cells out of 8 working. We have done manned testing with clients with 2 out of 8 cells working, and offered to demo it with one cell! We test only at 1 ATM, in air, but know immediately what it will do in pure O2 at 2 ATM, for example. If cells are checked better, before and during the dive, some surprises could be avoided, and at the same time you could finish a dive safely with just one sensor out of 3 working. I will write this up and publish it here as soon as I have a moment.

Meanwhile buy some decent cells and buy or make a cell checker - essential kit for Rebreather divers that don't have the trick up above yet. If I publish it here, hopefully everyone will have decent cell checks built in sometime.

Finally, we never did get any R22 cells that would last 36 months in their packaging and still perform completely adequately (or at all, in many cases). They do need replacing 2 years from the manufacturing data, so if less than a year old when you get them they can be accepted, you can use them for a year. I would not use cells in a rebreather for more than a year. This means manufacturers are not behaving improperly to sell you 11 month old cells, but they need to be clear: the cells should be fitted within a month and replaced after a year (as always).

Alex

Ben Field

Clearly I was joking...

Agree with the cell checker though, very good idea.

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Mdemon

Wow! You got a response?! Well done! I'm still waiting for a response to no less than two emails. Ho hum...

PS Can I have your old cells mate?

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heyydude

JUST as an interesting side-note - please do NOT take this as a recommendation......

In our warehouse, we've got all the Cis Lunar Mark 5P Inventory - of this, there is a big box of Teledyne R-17 Med sensors, which were manufactured in 1998. Yes, 10 years ago.

While working on a rig recently, I told my guy Charlie to grab some of the old cells to test the ROD (Redundant Oxygen Display) which tests the cells - expecting them to be dead, but to fit the bill for a simple test.

Guess what? They work just peachy. They read ppO2 in a linear fashion all the way up to 3 ata.

Go figure....

Must have been a banner year for Teledyne is the way I figure it - kinda like a 1998 Dom Perignon..

Kevin.

AD_ward9

Hi Ben, it was clear you were joking, as was my response. Sorry if my answer was too serious looking ... or Scottish humour a bit too subtle. I did try and put in the

Cheers,

Alex

marinetek1

fyi - Got my head back last week after a service with three new coaxial cells marked L7 - which I think is Dec07.

Lancer4545

Hi Kevin,

An interesting find!!

I run my cells until they no longer supply reliable information or are not servicable (for whatever reason) So far I have been able to plot a trend and can usually tell when a cell is going down hill. There is always the exception but generally you can pick them.

If it's supplying good reliable information why change it out for a cell that's unknown.

Always test the validity of the cell output by either using a cell checker or just do a linearity and a cell check at the BEGINNING of the dive.

Lance

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Mark Chase

No probs with coax its just the molex type. I made a nore of this in the origional post.

ATB

Mark

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