Non-O2 Clean Air in Nitrox tanks?

[DandyDon]

Keep in mind that if you rent the AL80's, besides the five lbs or so of extra lead you'll need to wear, you'll also need to adjust your dive plan to accommodate the fact that you'll be diving with roughly three-quarters the amount of gas that you're used to

Even if he uses his HP100s filled to 3,000#, how much air will he have in them then...?

 

[FWADIVER]

Even if he uses his HP100s filled to 3,000#, how much air will he have in them then...?

89 cubic feet @ 3000#

 

[MXGratefulDiver]

Even if he uses his HP100s filled to 3,000#, how much air will he have in them then...?

About 85 CF ... still about 10% more than an AL80 ...

... Bob (Grateful Dive)

 

[The Chairman]

CO contamination has nothing to do with being O2 clean.

I fully and completely disagree! Getting any contaminate in the tanks (usually oil) is a direct cause of CO in a tank. When pure O₂ is introduced to the tank, the contaminates oxidize creating CO. The contaminants build up over time, and the first partial pressure fill is the most dangerous.

I contacted the shop who did the fill that got me so sick, and I was the ONLY one to have an issue. Obviously, I originally thought it was THEIR mistake and had the owner of that shop quite concerned and a little defensive. It just doesn't seem reasonable that I was the only who would get sick off of their fills that day if it was their system. They do a partial pressure blending for their NitrOx, and it didn't take long before I figured out what really happened.

No Don, I didn't have the tanks analysed. However, I suffered the classic symptoms of CO poisoning: flu-like symptoms, a bit of vertigo, rosy fingernail beds and copious vomiting. I was only diving in 20 ft of water and thought I was coming down with the flu. I aborted the dive early, but on the boat I started feeling better and better. I hate missing a dive, so I decided to splash again after the immediate effects wore off. I had lots of air left, so I used the same tank. Within minutes I was vomiting with every breath. It finally occurred to me that my air was poisonous and I ascended.

I learned a few things that day.

• I don't trust partial pressure blending. I avoid it whenever possible.
• Sickness affects my critical thinking. What should have been obvious, just wasn't.
• If I call the first dive due to illness, there will be no second that day.
• You can vomit underwater, and it's just as horrid as doing it on the surface.

 

[FWADIVER]

I fully and completely disagree! Getting any contaminate in the tanks (usually oil) is a direct cause of CO in a tank. When pure O₂ is introduced to the tank, the contaminates oxidize creating CO. The contaminants build up over time, and the first partial pressure fill is the most dangerous.

Not disagreeing that oil in the tank can cause this problem, but the difference between E and modified E and o2 compatible or not wont cause that level of contamination. If there was enough oil in the tank to make you sick from oxidation, the previous user would have been feeling pretty light headed as well as having bad tasting air.

 

[The Chairman]

Not disagreeing that oil in the tank can cause this problem, but the difference between E and modified E and o2 compatible or not wont cause that level of contamination. If there was enough oil in the tank to make you sick from oxidation, the previous user would have been feeling pretty light headed as well as having bad tasting air.

If that were the case, then why do they mandate Modified E over E? Are you suggesting that they were just passing gas when they did that?

When a hot vapor enters a container, it tends to condense on a cooler surface. It doesn't matter how minute the vapor may be and the effect is cumulative. Once condensed, it will stay there until mechanically removed. Don't make the mistake and think that the tank cylinder is "hot". That's relative, and it is indeed cooler in relation to the much hotter gas.

 

[FWADIVER]

I understand the science probably better than you do, but I still find it hard to believe you would get enough contaminate to cause co poisoning. There are simpler ways to get co into the tank, and I tend to sign up for occams razor in a case like this, a bad bottle of welding o2 used for the pp fill is more likely, especially since the tank was never tested, and there are another half dozen gases that will produce similar metabolic symptoms as CO. This is getting too off topic now and i'll let it drop, but I think it is considered spreading misinformation by saying that non o2 compatible air is going to cause co poisoning.

 

[DandyDon]

About 85 CF ... still about 10% more than an AL80 ...

10% more than a AL80, 15% less than an HP100 filled to capacity - still an adjustment to be made. More lead needed with the AL80 sure, less in FW than SW he may be used to. The devil's in the details - always.

I hope he got his answers as this hijack is more interesting...

I fully and completely disagree! Getting any contaminate in the tanks (usually oil) is a direct cause of CO in a tank. When pure O₂ is introduced to the tank, the contaminates oxidize creating CO. The contaminants build up over time, and the first partial pressure fill is the most dangerous.

I am not clear on that? If oil is introduced into the tank and it builds up repeatedly, I can see a contamination and inhalation risk, but not where it turns to CO later under PP fill? You think that can happen when the tank is reheated by that fill?

I think more common is a faulty or overheated compressor leaks oil into the fill air, some partially combusted creating CO, some not combusted - both in the tank. We have some crude test of oil but only low ranger CO testers can check for the CO.

I contacted the shop who did the fill that got me so sick, and I was the ONLY one to have an issue Obviously, I originally thought it was THEIR mistake and had the owner of that shop quite concerned and a little defensive. It just doesn't seem reasonable that I was the only who would get sick off of their fills that day if it was their system. They do a partial pressure blending for their NitrOx, and it didn't take long before I figured out what really happened. .

But of course - always the case, or the wise claim for any business. Never admit guilt before a trial.

No Don, I didn't have the tanks analysed. However, I suffered the classic symptoms of CO poisoning: flu-like symptoms, a bit of vertigo, rosy fingernail beds and copious vomiting. I was only diving in 20 ft of water and thought I was coming down with the flu. I aborted the dive early, but on the boat I started feeling better and better. I hate missing a dive, so I decided to splash again after the immediate effects wore off. I had lots of air left, so I used the same tank.

You got ill on the first dive, then dived the same tank again?! :shocked2:

Within minutes I was vomiting with every breath. It finally occurred to me that my air was poisonous and I ascended.

I learned a few things that day.

• I don't trust partial pressure blending. I avoid it whenever possible.
• Sickness affects my critical thinking. What should have been obvious, just wasn't.
• If I call the first dive due to illness, there will be no second that day.
• You can vomit underwater, and it's just as horrid as doing it on the surface.

The numbers required to make you that ill at 20 ft are pretty significant. If you'd done a fast drop to 100 ft, acquired more CO loading under increased PP, then ascended - the way that CO binds with blood and does not off gas easily, well - it could have been grim.

I am so sorry to read that you did not test the air conclusively for CO, all too often the case as I mentioned above. These cases need to be documented with testing before the evidence is removed and the tanks cleaned. Tank CO testers were not as common then as now I know, but I hope you have one now - and use it often.

Spoiler

At this point I am thinking I probly owe you enough to buy you one, but I know how gifting works. Doesn't. If you want one, you have one; if you have one you didn't want, it's ignored. So I'll just keep nagging.

 

[ianr33]

They are due for VIP at the end of this month. The place we are camping at this weekend does not have O2 clean air to my knowledge as it is on a lake (Windy Point Park, Lake Travis, TX).

Why would anybody come from Florida to dive Travis?

 

[The Chairman]

I understand the science probably better than you do,

You can assume that I am clueless. The science is not that complicated so that even a moron like myself can understand it. Of course, working in a cryogenic Chem Lab at UF for four years has given me good solid foundation on contamination and how a small bit can ruin a lot of things.

but I still find it hard to believe you would get enough contaminate to cause co poisoning. There are simpler ways to get co into the tank, and I tend to sign up for occams razor in a case like this, a bad bottle of welding o2 used for the pp fill is more likely, especially since the tank was never tested, and there are another half dozen gases that will produce similar metabolic symptoms as CO.

Then why weren't there DOZENS of similar complaints? You get more than one fill off of a bottle of O2. As I pointed out, I was the only one from that shop that reported any problems at all.

This is getting too off topic now and i'll let it drop, but I think it is considered spreading misinformation by saying that non o2 compatible air is going to cause co poisoning.

How's that? The topic is "Non-O2 Clean Air in Nitrox tanks".

Speaking of Occams razor, what other gases could possibly be introduced into my cylinder? We know of only three. This was an electrical compressor far away from any internal combustion engine, so the introduction of CO is out. We do have the half of the materials needed to create CO introduced to the tank by the way of pure O₂. We also have the heat by the way of compression, that is needed for the process. They only thing we are missing is a contaminate.

The problem with many, if not most, Nitrox classes is that they present the ultimate horror of contamination as being a fire or explosion. Now, THAT would require a lot of contaminate. However, since Grade E air is not nearly as monitored as Modified Grade E, it's not that all uncommon for shops providing only Grade E to have significant problems with their system and just not know it.

Again, I ask you: why the need for Modified Grade E gas for partial pressure blending if there is no risk from simple Grade E? I believe that this is the industry norm and not a OSHA or CGA requirement.