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View Full Version : CCR O2 Cells on EBAY - Is this any of you lot?



PeterL
27-09-2014, 09:54 AM
http://www.ebay.co.uk/itm/Molex-rebreather-oxygen-sensors-used/111470372201

One is a year old the rest greater than 2 years and have been in a unit??

Really?

nickb
27-09-2014, 10:00 AM
Do we know anybody called Iain?

Paul Evans
27-09-2014, 10:11 AM
I've just read his description.

What's the problem with the ad ?:think:

PeterL
27-09-2014, 10:28 AM
I've just read his description.

What's the problem with the ad ?:think:

Read it with an eye for detail.... his 'age of cell piece'....

Paul Evans
27-09-2014, 10:38 AM
Read it with an eye for detail.... his 'age of cell piece'....

I did, He has stated clearly the age of the Cells. and this "All would be fine to be used in an oxygen analyser" And yes people do actually do this......

I,ll say it again, What's the problem with the ad?

Old saying "Buyer Beware" in this case he has clearly stated any information needed to make an informed choice.

This assumes the buyer isn't a Darwin Candidate.

BTS
27-09-2014, 10:43 AM
I see no problem with the ad and am wondering if they will fit my analox, anyone else want a couple to try in an analyser express interest here so we don't bid against each other, I am happy to buy them then share them out... so long as the price stays sensible....

PeterL
27-09-2014, 10:43 AM
So even though the seller is saying he can't use them in his unit and as the add so carefully states "dates cells were used from" this means none of them can be within manufacturers recommended age for safe use in any circumstance including your poor 32% numpty....

On each cell is a date of manufacture, that's the only date that counts.

BTS
27-09-2014, 10:44 AM
It is pretty simple Pete, you don't want them, don't bid...

gordyp
27-09-2014, 10:45 AM
If he gets a good price I'll start selling my old cells!

Paul Evans
27-09-2014, 10:51 AM
So even though the seller is saying he can't use them in his unit and as the add so carefully states "dates cells were used from" this means none of them can be within manufacturers recommended age for safe use in any circumstance including your poor 32% numpty....

On each cell is a date of manufacture, that's the only date that counts.

I have a cell in my analox that is 9 years old. it still see's 100%. every now and then I check it against a M8's who replaces his cell every year at a not inconsiderable cost.

Do I recommend we all do this; NO

Can I do it; Yes

PeterL
27-09-2014, 10:54 AM
It is pretty simple Pete, you don't want them, don't bid...

I forget about the overwhelming power of scrooge as it affects divers.
I won't be bidding but more so there's only one in that lot worth bidding on, I bin younger cells but then again I have seen people die from not doing so, yes I shan't be bidding.

BTW, Narked do a lovely set of adaptors to convert cell couplings if there's space in the box.

notdeadyet
27-09-2014, 10:57 AM
If he gets a good price I'll start selling my old cells!

Make sure you point out that white resideue on them is just salt.

notdeadyet
27-09-2014, 11:00 AM
What's the problem with the ad? He's not exactly selling crack to schoolkids.

He's selling some old cells that he clearly labels as old and not suitable for use in his rebreather. So what?

BTS
27-09-2014, 11:08 AM
I forget about the overwhelming power of scrooge as it affects divers.


That has fuck all to do with fuck all, recycling is not a bad thing. You can spunk your money away however you like, that is your prerogative, it doesn't give you the right to condescend though...

gordyp
27-09-2014, 11:22 AM
Make sure you point out that white resideue on them is just salt.

Maybe it is, maybe it isn't.........

Logun
27-09-2014, 11:51 AM
I see no problem with the ad and am wondering if they will fit my analox, anyone else want a couple to try in an analyser express interest here so we don't bid against each other, I am happy to buy them then share them out... so long as the price stays sensible....

I would be in, except my analox has a feckin JST connector. :(

Dsix36
28-09-2014, 06:41 PM
I have been recycling cells like this in my analyzers for several years and never an issue. My friends even give their old ones to me for recycling.

Timw
28-09-2014, 07:03 PM
I've passed quite a few old cells onto people on here that have asked for them to use for projects or analysers. Does that make me an evil person?

(I've also stuck them through my cell checker before I posted them so I didn't send anyone a dead cell and waste postage - does that redeem me a bit?)

David
28-09-2014, 09:51 PM
will be nice to watch the ebay sale sometimes things make very silly prices, but I would use one once validated.

Doomanic
28-09-2014, 10:31 PM
If anyone has a working cell, free to a good home, I'd be grateful for it for an analyser project. TIA.

Timw
29-09-2014, 07:44 AM
I've got one you can have. It may take a few dats to get it in the post as I'm a bit incapacitated at the moment. Pm me you address and I'll send it when I can. It's an ISC molex one.

iain/hsm
29-09-2014, 09:01 AM
SNIP I have seen people die from not doing so,

Really? When? Who? :think: Iain

Doomanic
29-09-2014, 09:09 AM
I've got one you can have. It may take a few dats to get it in the post as I'm a bit incapacitated at the moment. Pm me you address and I'll send it when I can. It's an ISC molex one.
Thanks Tim. PM sent.

FrogTec
29-09-2014, 01:02 PM
Cells in an analyser are very different to when in CCR. In the CCR it has to continue to read correctly as depth changes so needs to retain its calibration, so we change them very early. In an analyser you calibrate (generally) every use & are using it to confirm a static (probably) known gas. I have been reusing my cells for the past 4 years & changed analysers to facilitate their use.
Of note, divesoft and teledyne tek ox & vn202 use sentinel type cells.

notdeadyet
29-09-2014, 01:18 PM
Cells in an analyser are very different to when in CCR. In the CCR it has to continue to read correctly as depth changes so needs to retain its calibration, so we change them very early. In an analyser you calibrate (generally) every use & are using it to confirm a static (probably) known gas.

Cells are just dumb fuel cells. You cant calibrate a cell, you can only calibrate the measuring equipment.

I'm yet to see a cell fail in the way you suggest in ten years of diving rebreathers. In my experience they either die dead as disco or the top end goes gradually until it becomes noticeable in a cell checker or at 6m. The top end slowly dies and the error creeps downwards. That rate of decay is why rebreather cells need changing out sooner. A rb cell needs to hit 1.6 on target, an analyser never has to do better than 1.0. Obviously that decay is going to hit the rb cell first.



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FrogTec
29-09-2014, 01:22 PM
Semantics!

notdeadyet
29-09-2014, 01:37 PM
Yawn

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BTS
29-09-2014, 02:18 PM
Semantics!

Some say pedant, others say accurate...

ebt
29-09-2014, 03:13 PM
I think this is disgusting. Beating me to the idea of flogging of old cells on fleabay *sigh*

notdeadyet
29-09-2014, 03:18 PM
I flogged some old lime kegs. Got a fiver each.

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ebt
29-09-2014, 03:19 PM
wtf?!

Some people will buy any old shite. next you'll be seeing used apocs ;)

nigel hewitt
29-09-2014, 03:26 PM
next you'll be seeing used apocs ;)
futures

nickb
29-09-2014, 03:50 PM
Semantics!Only if 'semantics' means calling bullshit and giving a far more sensible and useful answer (it doesn't BTW (http://www.thefreedictionary.com/semantics))


Cells in an analyser are very different to when in CCR.This being the bullshit.

The cells in an analyser work in exactly the same way as those in a CCR. A chemical reaction results in a voltage and the chemicals and the anode involved get consumed. We dispose of CCR cells when they can no longer be relied upon to produce a linear response to a given PO2. That PO2 will vary according to personal preference and possibly the setpoint that the user chooses to dive with.

I normally dive with a PO2 of 1.3 and sometimes push 1.4 on deco. I like the certain knowledge that my cells are linear to at least 1.6 and can output 2.0

Most people trust that this will be the case for cells that are at least 12 months old, some trust that will be the case for cells that have been first opened and installed within the past 12 months.

Me, I use a cell checker to confirm linearity every few months and will push my PO2 over 1.6 on every descent. Two of my cells are dated July 2012 and were installed in my JJ in March 2013, they're still going strong.

When I finally bin them, they will almost certainly be good for use in an O2 analyser for a few more years.

jturner
29-09-2014, 03:57 PM
I flogged some old lime kegs. Got a fiver each.

I've got a couple if anyone wants any more...? Apparently, they can be made into neat 3L cylinder carriers.

FrogTec
29-09-2014, 04:00 PM
It's not even Friday and you lot are looking for a ruck!


Only if 'semantics' means calling bullshit and giving a far more sensible and useful answer (it doesn't BTW (http://www.thefreedictionary.com/semantics))

This being the bullshit.




Cells in an analyser only ever are at 1bar. The most they have to do is read to 1.00 ppo2. It is easy to Check calibration of the unit/cell before after analysis.
In the CCR it has to reliably read to about 2.2 ppo2 I would suggest in order to be reliable at the 1.3 (or whatever set point) otherwise you won't get a higher reading if needs be.

Hence the cell in Ccr is doing a very different job to the analyser as it will be reading a constant gas which will be changing as you ascend/descend.

And as to implying I suggested they were physically different cells!! I have already stated I use my sentinel cells in the analyser!! Mug! Read the post before going off on one nickb!

My reference to semantics was the reference to whether referring to calibrating cells as opposed to equipment.

nickb
29-09-2014, 04:08 PM
...a constant gas which will be changing as you ascend/descend...:rolleyes:

SoggyBottoms
29-09-2014, 04:10 PM
https://forum.woodenaxe.com/attachments/330x182px-ll-7dc6c095_micheal-jackson-eating-popcorn-theater-gif-gif.853/

FrogTec
29-09-2014, 04:57 PM
Nickb let me explain the basic principle of set point control on Ccr.

Let's say you are using air as diluent, and a set point of 1.2 ppo2.
At 20m the gas in the loop will be 40%, as you descend the gas will get weaker so at 50m you will have 20% in the loop. The cells will still be reading 1.2ppo2

Likewise as you ascend to do a stop at 6m, you will now have 75% in the loop, still reading 1.2 ppo2.

The cells need to cope with this hugely different range throughout the dive.

The analyser is analysing a constant gas which you probably know already (or should do) on the surface always in 1bar (or as near as damn it). You can not get an analayser above 1.0ppo2.

Hope this helps you understand, if not I can recommend a few Ccr instructors or books who could teach you.

I was in any way, agreeing that used Ccr cells are generally fine for use in an analyser.

Barrygoss
29-09-2014, 05:02 PM
Nickb let me explain the basic principle of set point control on Ccr.

Let's say you are using air as diluent, and a set point of 1.2 ppo2.
At 20m the gas in the loop will be 40%, as you descend the gas will get weaker so at 50m you will have 20% in the loop. The cells will still be reading 1.2ppo2

Likewise as you ascend to do a stop at 6m, you will now have 75% in the loop, still reading 1.2 ppo2.

The cells need to cope with this hugely different range throughout the dive.

The analyser is analysing a constant gas which you probably know already (or should do) on the surface always in 1bar (or as near as damn it). You can not get an analayser above 1.0ppo2.

Hope this helps you understand, if not I can recommend a few Ccr instructors or books who could teach you.

I was in any way, agreeing that used Ccr cells are generally fine for use in an analyser..

http://gamerindebt.co.uk/wp-content/uploads/2013/07/double-facepalm.jpg

B

nickb
29-09-2014, 05:30 PM
Let's say you are using air as diluentFirst mistake


At 20m the gas in the loop will be 40%, as you descend the gas will get weaker so at 50m you will have 20% in the loop

Likewise as you ascend to do a stop at 6m, you will now have 75% in the loopSo, not a 'constant' gas then?


The cells need to cope with this hugely different range throughout the diveJust as an analyser copes with a range of O2 %ages, from 0% to 100%

Where are you going with this stuff, aside from trying and failing to patronise me? The cells in a CCR are doing exactly the same thing as those in an analyser, generating a voltage (actually a current) that's hopefully directly proportional to the partial pressure of oxygen being presented to the cell membrane. The only difference is the environment in which this is being performed, where the pressure in the loop during a dive is greater than 1 bar.

nigel hewitt
29-09-2014, 05:39 PM
Let's say you are using air as diluent, and a set point of 1.2 ppo2.
At 20m the gas in the loop will be 40%, as you descend the gas will get weaker so at 50m you will have 20% in the loop. The cells will still be reading 1.2ppo2
Likewise as you ascend to do a stop at 6m, you will now have 75% in the loop, still reading 1.2 ppo2.
The cells need to cope with this hugely different range throughout the dive.
NOOOOO!
In this example the ppO2 hasn't changed. The oxygen applied to the cell is constant.
There is some other stuff and that's changing but the oxygen is being boringly constant, the cell will generate the same current so you get the same voltage out.

The whole thrust of Dalton's law is that you can consider the components separately.

ebt
29-09-2014, 05:49 PM
Froggy, I suspect you're well intentioned chap, but you're really just digging your hole bigger with every post :)

The reason the cells are no use for CCR use is we demand a high current output, proportionate to the high loop PO2. For analyser use you dont need either that high current response, or even that rate of response.... so we get away with it.

Anyway, its a moot point.... if someone doesnt want to buy it.... dont buy it. Theres enough nanny state holding as it is.

FrogTec
29-09-2014, 05:53 PM
Ebt, I never said they were, my point is when the cell is deemed no good for CCR it is prob still OK for analyser. I agree with your point, I suspect I am being cross read with somebody else's posts?

FrogTec
29-09-2014, 05:56 PM
Nick the constant gas was the analysis ref not Ccr, I made a grammatical mistake, should have read something like;
Hence the cell in Ccr is doing a very different job to the analyser (as it will be reading a constant gas) which will be changing as you ascend/descend.

Baron015
29-09-2014, 06:17 PM
The cells need to cope with this hugely different range throughout the dive.


What hugely different range ? On a dive my cells generally have to cope with range of 1.28 - 1.32 which doesn't seem like a big range. Seems pretty constant in fact.

FrogTec
29-09-2014, 06:47 PM
What hugely different range ? On a dive my cells generally have to cope with range of 1.28 - 1.32 which doesn't seem like a big range. Seems pretty constant in fact.

Hi,

.21 in air, .4 when prebreathed (sentinel) .7 when wet. Progressively up to set point assume 1.2, then maybe 1.4 on deco.

Not to mention other units which have to calibrate in 02.

I also expect that the cells would still read correctly way past 1.3 otherwise I would never know that I was hyperoxic.

Where as the analyser is only got to read 1 gas to a max 1.0

Baron015
29-09-2014, 06:57 PM
Hi,

.21 in air, .4 when prebreathed (sentinel) .7 when wet. Progressively up to set point assume 1.2, then maybe 1.4 on deco.

Not to mention other units which have to calibrate in 02.

I also expect that the cells would still read correctly way past 1.3 otherwise I would never know that I was hyperoxic.

Where as the analyser is only got to read 1 gas to a max 1.0

Well 0.21 and 0.4 are all in the range 0 - 1.0 so not sure why they are especially relevant. And cells calibrating in O2, also 1.0. I'm not sure where you are going with that any more.

I think people just reckon they are less worried about cells being current limited when in an analyser.

I also don't know anyone who calibrates their divesoft analyser every time they use it, especially as it really needs a two point calibration.

nigel hewitt
29-09-2014, 07:02 PM
I also don't know anyone who calibrates their divesoft analyser every time they use it, especially as it really needs a two point calibration.
ROTFL, Since about the only stuff I measure is 18/40 or less providing it still thinks air is 20.9 to 21.0 it's probably OK.

It's actually got a Sentinel 'spare' in it now. It had done its year unopened and it's the jack plug type.

FrogTec
29-09-2014, 07:06 PM
You can choose 1,2 or 3pt calib with the DS, but yes I don't every time as if it reads air when switched on. The first gas I test is the 02 so again if it reads 100% I am happy, I only calib if it is significantly out on 02.

The sig issue in Ccr is once in the water you are relying on calibration done a while ago but the cells are reading different pp02 at various times.

I would like to reiterate again, I never suggested at any time old cells were fine, that the Ccr acted the same as the analyser (otter than basic analysis). I was not against the notion of these advertised used cells having a second life in an analyser!

I appear to have been hounded upon due to an apparent reference to calibrating cells as opposed to the kit!

Anyway bored now!

Baron015
29-09-2014, 07:16 PM
I appear to have been hounded upon due to an apparent reference to calibrating cells as opposed to the kit!

Anyway bored now!

Well any discussion needs to have several viewpoints, else it's too dull....

Iainmct
30-09-2014, 07:11 AM
Hello, I'm Iain. I'm the one selling the cells on Ebay. I'm selling them because someone might get some use out of them. As has already been pointed out current limiting affects cells at the upper limit. If the device is calibrated they are perfectly safe to use in an oxygen analyser.

I don't for one moment think someone will use them in a rebreather. I find it hard to believe that anyone having completed mod 1 with any agency would choose to do so.

If I sell a car I cannot prevent someone from drinking alcohol and driving it. Nor am I responsible for someone else making poor decisions with cells. If they use old, secondhand cells in a rebreather the likelihood is that the existing cells in their unit are too old. However that is their responsibility and their choice.

Recently I have sold an unused ali 80, in test and oxygen clean. If an unqualified diver chooses to get an air fill, obtain regs' etc' and with no training dies using my cylinder again I am not responsible.

When I used to climb I replaced my ropes every year. I sold the old ones on eBay. Would I take those ropes up an alpine North face? No. Would I use them for top roping on an indoor wall. Absolutely.

We all make decisions in life. I believe in freedom to do so. I find dressing up in red, jumping on a horse and chasing a fox around a field a bit odd. Culling is one thing but to make a social event out of it I find distasteful. But I still think those who choose to do so have the right to.

I fully respect the opinion of those people who think I am wrong to sell my old cells. I do however disagree with your point of view.

Iain.

notdeadyet
30-09-2014, 08:06 AM
Good effort. I think it's a bit sad that you've had to come on and justify it. "Old cells for sale" isnt exactly "map of lost Inca gold mines for sale" but i guess others are less laid back. I guess there really is a dive police. Just demonstrates why I dont sell stuff on here any more.

I've just bought a batch of 12 Mark 15/16 cells from a government surplus place in the US. All hitting their shelf life today. Dont even know what I'm going to use them but they were cheap enough I'm happy to bin 11 of them.

I might even put them into my homebuild just to add insult to injury.

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nickb
30-09-2014, 08:09 AM
A few more analogies might help you get your message across better Iain ;)

Baron015
30-09-2014, 08:18 AM
I didn't actually see anyone saying Iain was wrong to sell his used cells. I wonder why he had to write such a long post.

dwhitlow
30-09-2014, 08:56 AM
Some useful and some amusing points made in this thread and I am thinking some would benefit from listening to John Lamb deliver his presentation on oxygen sensors. I listen to him at Eurotek and picked up a (free) copy of his book...

Whilst the book is old, his opening comment was that nothing has changed since he wrote the book (although he will son be releasing a separate book about CCR issues) and for those who did not attend it might be informative.

The Practice of Oxygen-Measurement For Divers by John Lamb (http://www.amazon.co.uk/The-Practice-Oxygen-Measurement-Divers/dp/0941332683)

BTS
30-09-2014, 08:58 AM
Some useful and some amusing points made in this thread and I am thinking some would benefit from listening to John Lamb deliver his presentation on oxygen sensors. I listen to him at Eurotek and picked up a (free) copy of his book...

Whilst the book is old, his opening comment was that nothing has changed since he wrote the book (although he will son be releasing a separate book about CCR issues) and for those who did not attend it might be informative.

The Practice of Oxygen-Measurement For Divers by John Lamb (http://www.amazon.co.uk/The-Practice-Oxygen-Measurement-Divers/dp/0941332683)

Sixty three quid!!! I will take my chances with ignorance, it has served me well so far....

nickb
30-09-2014, 09:00 AM
Sixty three quid!!! I will take my chances with ignorance, it has served me well so far....I bought mine from Vandagraph for a fiver.

dwhitlow
30-09-2014, 09:02 AM
Sixty three quid!!! I will take my chances with ignorance, it has served me well so far....
:clap::giggle::rofl:I didn't even spot the price as I picked it up free. try this instead http://www.narkedat90.com/Oxygen_measurement_for_divers_p/omfdbook.htm

dwhitlow
30-09-2014, 09:03 AM
I bought mine from Vandagraph for a fiver.
here..http://www.vandagraph.co.uk/?uid=&sessionid=&page=catagory&cat=310

notdeadyet
30-09-2014, 09:19 AM
I didn't actually see anyone saying Iain was wrong to sell his used cells. I wonder why he had to write such a long post.

I'm not sure how else I would take the OP's first couple of posts other than criticism. Perhaps we just read things differently. Maybe the OP's "Really?" comment was a genuine request for confirmation from others rather than the sarcasm I took it for.



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Baron015
30-09-2014, 09:28 AM
I'm not sure how else I would take the OP's first couple of posts other than criticism. Perhaps we just read things differently. Maybe the OP's "Really?" comment was a genuine request for confirmation from others rather than the sarcasm I took it for.


I thought "Really?" was just incredulity that there could be any buyers for these items.

dwhitlow
30-09-2014, 09:40 AM
I'm not sure how else I would take the OP's first couple of posts other than criticism. Perhaps we just read things differently. Maybe the OP's "Really?" comment was a genuine request for confirmation from others rather than the sarcasm I took it for.

I am sure the concern from the OP is that people might be tempted to use an old cell in the belief that a cell that performed correctly in the pressure pot to 2 bar will perform equally well on a dive. This is not a safe assumption.

John Lamb, based on many years years of measuring and manufacturing reliable oxygen sensors, was very clear surface tests are not adequate. Even the practice of running oxygen to 6m (to get ppo2 of 1.6) will not reveal a cell is due to fail.

Once the scrubber gets to full temperature (~50c), the humidity to 100% and the absolute pressure to a number of bar, then do you have the conditions in which the cell is most likely to fail. That might take 20 minutes.

John did observe that a cell pushed to 1.6 bar at the end of the dive will be good for the next dive and this is the time to check your cells.

Just to support this further, I had a cell fail on 31st August. It was an 18 month old Vandagraph cell (aka N@90 NaNS01) which was due for replacement in September and failed to reach 1.3 on the dive. After I returned home I checked it in the pot and it was happy to go to 2 bar! I no longer see my old cells as potential spares.

notdeadyet
30-09-2014, 09:50 AM
Any rebreather diver that fooking stupid to assume a 2 year old used cell is good for sticking in a box then it's a public service to encourage them along the way.

I still dont get the concern. The seller never mentioned anything about using them in a unit. If I remember right the ad says he wouldnt use them.

As I said, this is an example of why I'd never sell anything on here any more.

It's an ad for some used cells that someone might get some mileage out of. He's not selling crack.

How come no-one gives a hard time to people on here asking for used cells?

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Darren A
30-09-2014, 05:19 PM
Dont even know what I'm going to use them but they were cheap enough I'm happy to bin 11 of them.

Don't bin them, put them on eBay :)


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