Nitrox Analyzer - How many use one?

[stuartv]

There is always a tester on the boat.

Not necessarily. I bought my own Analox tester after diving in Hawaii where the dive shop brought me Nitrox tanks to the boat, but they didn't bring an analyzer and there was not one on the boat and no other divers on the boat had one, either. I had to choose to dive unanalyzed "EAN32" or take the DMs tanks of air. I took the air.

Caveats: Newbie, not nitrox certified (yet), but you all posted in basic so you get basic questions.

What is the thought on the two tests? A leaky valve letting something in or out between shop and dive? Verifying what was written on the tape? Do some of the gasses "degrade" in a chemical reaction and change structure with time? Just curious as I will probably get there sooner rather than later.

Analyzing the tank won't tell you if the tank leaked. Re-analyzing catches:

- original analyzer was wrong (bad calibration, bad O2 sensor, operator error)
- mistake in labeling
- in-tank mixing. Not so common, IME, for Nitrox, but it definitely seems that the measured mix in a tank of trimix can change between when the tank is first filled and when it sits for a while.
- change in O2 content due to in-tank oxidation

I'm pretty sure that's not gonna change anything, but I can't be bothered doing the maths.

One of the incidents described in Diver Down (IIRC), was one where a diver took a steel tank out for a quick, shallow dip in a lake and died. Between the time of the fill and the time of use, moisture in the tank oxidized so much steel into rust that the O2 content left in the tank was hypoxic. That tank definitely sat for a while between the fill and use, but still...

Nitrox has never been proven to reduce so called decompression stress or give more energy or whatever. It does one thing and only one thing- it reduces the amount of Nitrogen absorption in the body when breathing compressed air at depth. Period.

Absence of proof does not constitute proof of absence.

Less nitrogen absorbed means less bubbling on ascent. You do realize you get micro bubbles even on a "perfect" ascent from a conservative NDL dive, right? Do you really insist that micro bubbles that are formed will never have ANY effect on the diver, even though they show no "recognized" symptoms of DCS? You insist that micro bubbles would never result in a diver feeling some fatigue that the diver would not experience if they had less micro bubbles?

 

[stuartv]

I don't have any hard and fast rules other than I carry my own analyzer in my dive bag and I always analyze any tank that is purported to have Nitrox in it and usually any tank even if it is just purported to have Air in it. I have seen enough dive shop fill stations to believe that it is entirely possible that a tank that was supposedly filled with Air could actually have been filled from a Nitrox bank by accident. Especially if the tank has a big Nitrox sticker on it.

Some of my tanks have the big Nitrox sticker and yet I sometimes request them to be filled with (Oxygen Compatible) Air. Why would I ASSUME that they were actually filled with Air when I'm not willing to ASSUME that a request for Nitrox actually got me the requested gas? IOW, if there is a reason to analyze a tank that is supposed to have Nitrox, I think there is just as much reason (in general) to analyze a tank that is supposed to have Air.

 

[Jack Hammer]

I had to choose to dive unanalyzed "EAN32" or take the DMs tanks of air. I took the air.

Deciding one unanalyzed tank is safer than another unanalyzed tank is kind of pointless without a lot more information. You seem to state that below.

IOW, if there is a reason to analyze a tank that is supposed to have Nitrox, I think there is just as much reason (in general) to analyze a tank that is supposed to have Air.

I think the take away should be that unanalyzed is unanalyzed, regardless if it's supposed to be "just" air, Nitrox, or other.

Even though this thread is about Nitrox analyzing, it's also important to think about the importance of CO analyzing. I do both to my tanks at the same time.

 

[stuartv]

Deciding one unanalyzed tank is safer than another unanalyzed tank is kind of pointless without a lot more information. You seem to state that below.


I think the take away should be that unanalyzed is unanalyzed, regardless if it's supposed to be "just" air, Nitrox, or other.

You make a good point.

At that time, I felt okay taking a tank they told me they filled with air versus taking a tank they told me they partial pressure blended to 32%.

But, as you say, unanalyzed is unanalyzed. And I bought my own analyzer before the next time I went diving...

 

[rek_diver]

Absence of proof does not constitute proof of absence.

Less nitrogen absorbed means less bubbling on ascent. You do realize you get micro bubbles even on a "perfect" ascent from a conservative NDL dive, right? Do you really insist that micro bubbles that are formed will never have ANY effect on the diver, even though they show no "recognized" symptoms of DCS? You insist that micro bubbles would never result in a diver feeling some fatigue that the diver would not experience if they had less micro bubbles?

I insist that there is no scientific evidence to support your claims and until and unless scientific (or medical) evidence does appear to support such a statement, I will conclude there is no truth to it.

You could say "Absence of proof doesn't mean there isn't a Santa Claus".

In both cases, it's saying, well, nothing.

 

[Storker]

You could say "Absence of proof doesn't mean there isn't a Santa Claus".

"Absence of proof does not constitute proof of absence" is kinda more general and a lot more plausible that your fairly specific "Absence of proof doesn't mean there isn't a Santa Claus"

 

[rek_diver]

Sure Storker, whatever you say.

You may not require evidence of any sort but I do.

It's one of those, to each his own sort of thing. As long as you aren't selling snake oil I have no issue with you, and safe diving.

 

[Lorenzoid]

I insist that there is no scientific evidence to support your claims and until and unless scientific (or medical) evidence does appear to support such a statement, I will conclude there is no truth to it.

You people seem all to be in agreement--you're just not reading the other's statements literally. It seems to me:

• Stuart did not make any "claims"; he just pointed out that there is some logic behind the hypothesis, which being just a hypothesis may or may not be proven true at some point by scientific methods. It may never be proven true because it's hard to measure how someone feels, among other reasons. Because the logic about the possible effect of subclinical bubbles on the immune response seems compelling to researchers, I suspect more studies will be attempted.
• There is some anecdotal "evidence" supporting the hypothesis; people have said Nitrox makes them feel better. It's evidence, just not very reliable evidence. It isn't statistical evidence.
• The one scientific study cited on DevonDiver's page involving 18 chamber divers did not find any statistical evidence to support the hypothesis and drew its conclusion from that, and that's all. The study didn't conclude that "there is no truth to it," as you do.

As you all seemed to agree above, if someone believes Nitrox makes him feel better, that's a good enough reason for him to dive Nitrox.

 

[stuartv]

I insist that there is no scientific evidence to support your claims and until and unless scientific (or medical) evidence does appear to support such a statement, I will conclude there is no truth to it.

You could say "Absence of proof doesn't mean there isn't a Santa Claus".

In both cases, it's saying, well, nothing.

Is there any scientific evidence to say that Nitrox does not ever help reduce fatigue (i.e. proof of absence)? I don't think there is.

But, there are lots of people saying that it does help them. It's not "scientific" evidence. It's anecdotal evidence.

When there is no evidence that it explicitly does not exist and there is anecdotal evidence that it does exist, it seems that a rigorous scientist would conclude that it MAY exist.

 

[rek_diver]

Then there is no evidence that it explicitly does not exist and there is anecdotal evidence that it does exist, it seems that a rigorous scientist would conclude that it MAY exist.

In the absence of a conclusive controlled clinical study using placebos, a rigorous scientist might, but not a competent one.