Analyzer: Nitrox vs. CO

[DandyDon]

The incidences of CO poisoning are absolutely tiny, way way less than the number of O2 tox incidents.

What do you base that claim on? Anything...?

When Padi required quarterly tests and some centers did them, 3% failed - a significant portion of those by large amounts. Safe...?

DAN admits that they have no idea how many drownings were caused by CO poisoning as the required testing is seldom done at many destinations and even if it is done - the findings are easy to hide in many countries to protect tourism.

Simply put, if you don't test - you do not know, just diving on hope. Inline units are $600+ USD plus frieght and shipping but the total costs spread out over the life of filling tanks is pennies/tank - not many pennies at that.

Paranoid huh?

The scuba sport & industry was certainly developed before SPGs, Octs, computers, and more recent developments of low cost, easy to use personal CO testers, so much of the industry is still stuck in bad habits with regard to air quality. And with many Instructors hiding their heads, resolving this unneeded risk is challenging.

True, the actual known body count for scuba deaths is relatively low so CO deaths must be lower than that, so if that's good enough for you - cool. I'll keep wearing safety belts in moving vehicles, float vests in moving boats, and testing my tanks before I take them to depth. The inconveniences are small and the uncommon negative results are great.

 

[Quero]

Each case is different.

I don't have a CO analyzer myself, so seeing me recommend that a person buy one of those before buying an O2 analyzer might seem odd, particularly since I don't have any firm intention of purchasing a CO analyzer right away and I do own an O2 analyzer. However, I teach Nitrox and I need an O2 analyzer as a teaching/learning tool.

In your case, if you are certain you want to invest in both eventually and want to cover as many bases as possible as early as you can, getting the CO analyzer first will do this. I have never seen a CO analyzer for customer use at any dive operator, so if you want to analyze your air, you will need to provide the tools yourself. OTOH, when you buy Nitrox, the filling station or the boat operator will have an analyzer available for customer use, so owning your own is not critical.

 

[String]

What do you base that claim on? Anything...?

Real life incident reports from every country ive ever seen.

And HSE data on air quality testing.

 

[DandyDon]

Real incidents have all too easy to hide, but that's changing with economical technology. Sorry you don't want to help with the solution.

 

[Belmont]

I diver I met died a few years ago in Mexico, of CO poisoning.
It's a different feeling when you can put a face and a name on some statistics.

 

[String]

Real incidents have all too easy to hide

and your proof of that unsubstantiated claim is where exactly?

 

[sambolino44]

Interesting. I can understand why somebody might say, "I wouldn't get one; I don't think it's necessary." But to elevate that to "You shouldn't get one; you're being paranoid" is, well, I guess I just don't understand why somebody would say that. What do you care what I do with my money?

For one thing, every Nitrox fill station I've ever gotten fills at (that's only a few places) has an O2 analyzer, and has me observe, or perform, the calibration and analysis. I've never seen a CO analyzer anywhere. An O2 analyzer would be used on the minority of my fills, and they are available; a CO analyzer would be used on every fill, and nobody has one.

I can understand the sentiment of, "You're worried about something that's not really a problem." I don't understand the negative, "You're being paranoid and stupid." vibe I get from some of these responses.

 

[sambolino44]

...But the crucial point not being picked up here is that CO is undetectable by "smelling it". The training litany is that we should reject any breathing air that "smells or tastes bad", but CO is ODORLESS AND TASTELESS. What that means is, unlike the air with a "bread smell", if CO's in there by itself, you're not going to know it.

...CO analyser also doesnt check for anything else potential nasty and undetectable in the gas mix either.

I understand that CO is undetectable, but the fact that the air smelled weird made me think that maybe there's something else in there besides air. One time it smelled kind of like plastic, but unlike anything I've ever smelled before, although I have detected that same smell (much fainter) in other tanks filled at other places since then. The bread dough smell was only one time.

From my brief research, I've gotten conflicting answers to the question of should you be able to smell anything in SCUBA air, and if so, is that necessarily bad.

I imagine CO may be the most common bad thing that can get into SCUBA cylinders, but I highly doubt it's the only thing. I wonder what else could be in there that could do harm, and what that harm might be. I wouldn't call that paranoid. If I'd said, "I'll bet there are other bad things in there." then that would be paranoid.

The thing is, as far as I understand materials analysis, you have to have some kind of idea what you're looking for; you can't just do a full mass spectrometry analysis on every fill because it's so expensive. I wonder if anyone's ever done one at all. But that's besides the point. I think CO may be more common than is commonly realized, it is recognized as one of the more common "failure modes" in SCUBA air, a reasonably-priced analyzer is, or will soon be, available, so that's why I started the poll.

Oh, yeah, String, what's HSE? Do you mean the UK's Health and Safety Executive?

 

[lmorin]

I understand that CO is undetectable, but the fact that the air smelled weird made me think that maybe there's something else in there besides air. One time it smelled kind of like plastic, but unlike anything I've ever smelled before, although I have detected that same smell (much fainter) in other tanks filled at other places since then. The bread dough smell was only one time

...................

While CO itself might be odorless, it is the product of incomplete combustion. This, with a reasonably high degree of probability, means that other junk such as incompletely burned gas or oil exhaust will also be present. These would be likely to have a detectable odor, assuming the concentration is high enough.

 

[bleeb]

Padi used to require quarterly air tests by one of the two accredited labs, and one of them stated they saw a 3% failure rate - and when they failed, they often failed at very dangerous levels.

I vaguely remember reading a few different versions of this. Does anyone have the exact reference to this statistic? It would be useful to confirm which test lab said this, whether the 3% value is what they actually said, whether they were talking specifically about PADI-required tests or general dive compressor operator tests or results from all their tests in general, geographic region of coverage, whether they were talking about gas for hyperbaric or surface applications (i.e. firefighter SCBA), whether they were tests for Grade D air that would have failed Grade E or enhanced CO tests but those weren't what was being asked for, etc.