Info ALWAYS analyze your gas!!!

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tursiops

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Do you have any recommendations for a good analyzer?
They are all good, if they have working sensors and are calibrated. They are all bad, otherwise.
When you pay more you get more robustness and bells/whistles.
 

Tigerpaw

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Divesoft is pretty much the gold standard analyzer. You can get them in a few varieties, Tri-Mix or just O2. There are others and some of them are cheaper and some are not as cheap. But, Divesoft has a great name in the analyzer field.
Thank you
 
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tbone1004

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Do you have any recommendations for a good analyzer?
Functionally they're all the same since they are just a digital conversion of an analog signal from the same types of galvanic sensors. I like the Palm O2 personally and tend to use that one the most. I do own a Divesoft and my PalmO2 has a bc inflator QD on it which is convenient.
 

NW Dive Dawg

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OK.... Probably a super dumb question but here goes.

An O2 analyzer is great for it's intended purpose of confirming O2 percentage...... but do they make an analyzer that will confirm any substantial or consequential existence of Carbon Monoxide or other "non- nitrogen" or non-O2 gas?

I understand that in "air" there will almost always be some very minimal (less than 1%) and harmless "trace" gases like Helium, Argon, Cow Farts, etc........ but is there an analyzer that will confirm that your gas doesn't contain any poison like CO?
 

broncobowsher

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What are normal failure modes for o2 sensors out of curiosity?
It is called "current limited". That is it won't read the higher concentrations.
At the start of the failure it will read fine up to something like 90%, anything above 90% will just read 90%.
As it further ages the upper reading will continue to drop. It will read up to 50% and any concentration above that will just read as 50%. That is the more common O2 sensor failure.

Reading an excessively high O2 reading is very uncommon. Mechanical failure of the electrical circuit in the cell. Not the normal cell aging out.
 

tursiops

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OK.... Probably a super dumb question but here goes.

An O2 analyzer is great for it's intended purpose of confirming O2 percentage...... but do they make an analyzer that will confirm any substantial or consequential existence of Carbon Monoxide or other "non- nitrogen" or non-O2 gas?

I understand that in "air" there will almost always be some very minimal (less than 1%) and harmless "trace" gases like Helium, Argon, Cow Farts, etc........ but is there an analyzer that will confirm that your gas doesn't contain any poison like CO?
You can get an analyzer for everything, but only some things are affordable. Yes, you can get an analyzer for CO.
Plus other, less effective but cheaper options, such as:
 

JMBL

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Friendly reminder after an exciting analysis today for everyone to check their gas.
I have a large quantity of AL80's for bailout, deco, stage, etc. I'm heading down to Ft. Lauderdale to dive with @LandonL @jlouder and my mother for the weekend and just grabbed the first stage bottle out of the rack which is pretty normal when I'm diving single tanks since I don't use DIR style rigging with the handle. Bottle has a MOD120 sticker on it but no analysis sticker so I'm thinking it's full of EAN32, like one would. It feels a touch light so I hook it up to the fill station and it's got 2400psi in it so I figure I'll top it off. Hand J the analyzer as it's coming off the whip and she looks a bit bug-eyed and says "uhhh it says 77..... you check it*. I checked it, 77. This is not a normal failure mode for an O2 sensor, and it shouldn't have been that high. I knew the bank wasn't full of O2 because the other two bottles came off normal so I grab my analyzer from the truck and lo and behold, 77%. I wouldn't have knowingly put O2 in a bottle with a MOD120 sticker on there, but my bottles get borrowed by people pretty regularly and who knows when this was last dove. Stuff happens, but ALWAYS analyze your tanks because sometimes it can save your life.

Had just that kind of talk 2 weeks ago. A friend didn't want to analyse his BO tank, saying : we just filled it, I know what's inside. The boss answered : just indulge me, for argument sake (he obviously had something else in his mind). And of course, my friend had the wrong mix. Boss just quoted : what does look like a S80 better than another S80, among a crowd of them ?
 
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tbone1004

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OK.... Probably a super dumb question but here goes.

An O2 analyzer is great for it's intended purpose of confirming O2 percentage...... but do they make an analyzer that will confirm any substantial or consequential existence of Carbon Monoxide or other "non- nitrogen" or non-O2 gas?

I understand that in "air" there will almost always be some very minimal (less than 1%) and harmless "trace" gases like Helium, Argon, Cow Farts, etc........ but is there an analyzer that will confirm that your gas doesn't contain any poison like CO?

The Cootwo was produced with a CO sensor integrated. Unfortunately the company was plagued with terrible customer service and is now defunct. I do wish that @jjbosquez can convince Divesoft to put a CO sensor in their analyzer but we have been unsuccessful for many years asking them to do so.

What are normal failure modes for o2 sensors out of curiosity?
there are very few dumb questions, and even fewer super dumb questions. Unless you are a CCR diver AND were taught by a truly qualified instructor *of which there are even fewer than there are super dumb questions* and/or have done your homework on Scubaboard thanks to guys like @Bobby it is highly unlikely you were taught anything about the failure modes of galvanic oxygen sensors.

The failure mode that I was referencing is a cell becoming nonlinear. Galvanic oxygen sensors produce voltage in the presence of oxygen and that voltage is considered to be a linear relationship. Using easy numbers *assuming Air is 20% O2 or ppO2 0.2 since the sensors measure ppO2* a sensor that reads 10mV in air will read 50mV when exposed to pure oxygen at the surface or a ppO2 of 1.0
When a cell starts to degrade, instead of reading 50mV it may read 45mV and as it gets worse it may go even lower. What would be a very rare failure mode is if that cell read 55mV and was "over-linear". I have never seen it but I believe Bobby has had it happen to him once or twice over the last 30 years. Linearity is the reason that you always want to calibrate an analyzer close to the ppO2 that you are trying to analyze. On a rebreather we calibrate using a ppO2 of 1.0 because we will typically be analyzing from 1.0 to 1.6. With an oxygen analyzer when you are analyzing nitrox, you want to calibrate using air because 0.21 is much closer to 0.32 and will give you a more accurate reading.

The other primary failure mode of cells is current limiting. This typically occurs at the same time as a cell becoming non-linear but not necessarily so. This is not typically an issue that oxygen analyzers would encounter as the current limiting is typically encountered in rebreathers where a cell will no longer be able to read at a ppO2 of 1.6, but if a cell degrades enough it could become limited below a ppO2 of 1.0.
 
https://www.shearwater.com/products/peregrine/

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