Close to 100% nitrogen in an old tank?

[Landau]

Kurtis, sorry for your loss.

Do you know if the coroner is going to hold a full inquiry? These are rare in BC but they do release very complete and public reports.

I was part of a coroner's inquest jury many years ago and was very impressed with the entire proceedings. (I was also part of a criminal jury and not impressed at all.)

 

[Bob DBF]

My last LDS was the paintball fill station for those that didn’t have their own compressor.

 

[Costas Bakopanos]

Hi All,

Had a friend pass from a diving accident last fall. The coroner just got back to his family with info. I didn't speak to the coroner directly and this information is second hand.

However, I have been told that his aluminum pony bottle was filled with almost 100% nitrogen and I can't make sense of how that would happen?

I believe he hadn't used that bottle for a couple of years but don't know that for sure. Is there anyway anyone could think a pony bottle could accidentally get filled with nitrogen? Or if there is some type of oxidization process on the inside of a tank after a long period of time that could increase nitrogen levels?

I will be following up to see if I can read the report to confirm this information. It would obviously make a lot more sense if it were filled with 100% O2 and he didn't realize it and switched gasses too deep.

Thanks for any information in advance

I am sorry to hear this. It's a pity to have such accidents.
I have a rule that I follow when I mix for someone and when I dive my own mix or the mix someone is offering me.
Always check twice: the blender checks and marks and the diver checks and marks.

I can't figure out any possible way that oxygen levels went down or the tank was filled with nitrogen.
A possible scenario is that he got a hypoxic mix filled, probably with very low oxygen and high Helium?
I cannot think of any dive professional having a use case for using pure nitrogen.

 

[O-ring]

The only diving use of pure nitrogen that I can even remember being a thing was the recommendation for using it to dry steel tanks after o2 cleaning to prevent flash rust. The theory being that blowing pure nitrogen into the tank to dry it would stop the flash rust caused by the interaction of the wet tank and oxygen in the surrounding air if you let it drip dry inverted or rigged up a fan blowing ambient air into it. That being said, nobody I know actually went to the trouble to do it so nobody had nitrogen cylinders lying around.

 

[Jonn]

I cannot think of any dive professional having a use case for using pure nitrogen.

The car tire filling thing would explain it. The performance gain is a bit marginal but some people swear by nitrogen in tires, especially in the motorcycle and racer crowd but also with those new tire pressure sensors in variable weather. If you’re doing it yourself in your garage and have your own tanks lying around, using one for that is the obvious solution. It’s hard to be disciplined about labeling when it’s just you in there; it’s easy to tell yourself “I’ll just remember”...
Not saying that’s what happened, but the story sort of tells itself.

 

[Chris H]

I've used nitrogen to dry my tanks as O-ring describes. I also worked in a gas analysis lab. As others have mentioned, you often analyze for the known component, not the unknown. In the case of Air analysis, you check the Oxygen content. I agree, that in the case of a fatality, you would want an actual analysis on the gas makeup. Some sort of filling error, or assumption about contents, is much more likely than a % quantity of Oxygen being consumed by something going on inside the cylinder. As a side note, the company I worked for did not have an air compressor. They made synthetic air by mixing Oxygen and Nitrogen. When you make air like that, every cylinder needs to be analyzed for Oxygen content before it can go out to customers.

 

[BRT]

The only diving use of pure nitrogen that I can even remember being a thing was the recommendation for using it to dry steel tanks after o2 cleaning to prevent flash rust. The theory being that blowing pure nitrogen into the tank to dry it would stop the flash rust caused by the interaction of the wet tank and oxygen in the surrounding air if you let it drip dry inverted or rigged up a fan blowing ambient air into it. That being said, nobody I know actually went to the trouble to do it so nobody had nitrogen cylinders lying around.

I've done it. It works.

 

[O-ring]

I've done it. It works.

The science certainly makes sense. I just never knew anybody willing to go to the trouble/expense to procure nitrogen to do it so have never seen it in person.

 

[nadwidny]

The science certainly makes sense. I just never knew anybody willing to go to the trouble/expense to procure nitrogen to do it so have never seen it in person.

Nitrogen is cheap.

 

[BlueTrin]

Nitrogen is cheap.

But cylinders don’t rust that badly under normal usage, isn’t it ? Are you saving money by doing this ?

(real question here)