Nitrox Storage Question

[iztok]

Citing a 30 year old study?

Did chemical properties change that much since the last study? Can you point to the flaws of the study or are you just discarding it for being 30 years old?

Perhaps some constructive input explaining where the above mentioned study is wrong and why would benefit all of us.

 

[iztok]

5 MINUTES into his dive on 2-3% oxygen before stopping? Somehow i doubt anyone would last THAT long!

Well I guess brain takes about 5-6 minutes before there is irreversible brain damage.

 

[Doc Harry]

Did chemical properties change that much since the last study? Can you point to the flaws of the study or are you just discarding it for being 30 years old?

Perhaps some constructive input explaining where the above mentioned study is wrong and why would benefit all of us.

If you read my post regarding long-term storage, I reviewed all of the studies in detail, including the extensive limitations of the methods, analysis and conclusions.

All of these studies are old, and most of the methods are quite questionable -- but nonetheless they offer some insight into some of the problems that can be encountered with cylinder storage. As bad as the data is, this data is all we have. No one else has done any other studies since.

Industry leaders (CGA, PSI, etc.) have made numerous recommendations regarding cylinder handling based on these studies -- annual VIPs are just one such practice that resulted from these "old, outdated" studies. We can all make our own decisions if we read the original data and draw our own educated conclusions.

Personally, I follow industry recommendations. But, in my opinion, the bottom line is that if you will stay out of trouble 99.999999999% of the time if you get your cylinders inspected annually, get a hydro every 5 years, and get your air fills from a well-maintained compressor.

'nuff said.

P.S. Oh, yeah, and don't breath old gas without testing it first

 

[HowardE]

Did chemical properties change that much since the last study? Can you point to the flaws of the study or are you just discarding it for being 30 years old?

Perhaps some constructive input explaining where the above mentioned study is wrong and why would benefit all of us.

You read it? It uses far fetched scenarios. 500 ml's of water in a tank stored at 104 degrees F for 3 months?

Tanks are now days (for the most part) VIP'ed EVERY YEAR. These checks are for RUST (oxidation), as well as other potential flaws. Unless somehow 8 OUNCES of water end up in your tank - without your knowledge, and you leave them sitting at 100 degrees, and not VIP'ed ever, then MAYBE you can re-create this far fetched scenario.

At the same time...

My original statement stands. ANALYZE the gas first. If the mix is the same... Your gas is good as the day you put it in the tank. IF there was substantial oxidation - the mix would not be the same, and therefore an analysis of the gas would reveal that.

 

[Cave Diver]

Did chemical properties change that much since the last study?

One thing that has changed is the use of liners in tanks. How much that will affect the situation being described, I have no idea. Maybe none at all.

The decision to use a tank that has been sitting is a personal one, which I hope would be influenced by the care that was taken with it. I would also analyze it and compare the results to the contents sticker.

If in doubt, dump it. Gas is cheap unless it's trimix. Which in that case I'd probably dump it anyway simply due to the elevated partial pressure it would be used at.

 

[HowardE]

Another thing that has changed since 1976 is the use of J valves, and the amount of water that could end up in your tank. Unless you were underwater, sucked your tank completely dry, and then breathed a regulator FULL OF WATER, you would never get more than a few drops of water in your tank. IF you did this... would you not VIP your tank right away?

Currently - the only way to get water would be from residual droplets left in the tank valve, if you fill your tank when it's wet, or if the line from the fill station had a few droplets. This would not cause substantial oxidation inside a tank.

But again... A simple analysis of the gas would reveal if there was oxidation, and the percentage of the mix degraded.

 

[riverdiver]

WHAT? Gas is fine so are the tanks. I have been mixing gas in my garage for years, some of the tanks that I rent are MED. grade oxygen bottles that are from the 1950's and 1960's, That tank has a valve that holds the mix in their at 3500 psi so it also holds out at 3500 psi.
And the VIP no big deal that is so the dive shops can make money from you every year. but do get a hydro when do.