How long is it safe to store air in your scuba tanks?

[Bogie]

How long is it safe to store air in your scuba tanks safely without resupplying with fresh air?

I personally would not use air that was over 60 days. (just my preference)

How does Oxygen content degrade in stored scuba tanks? You start with an air fill with the normal 21% Oxygen. If you store a full tank for 3,6, or 12 months does the Oxygen content decrease? What if stored longer 2, 3, 5 years? Does temperature, moisture, or other factors contribute? What about type and physical make up (steel, AL, composite) of the tank? Are there other factors (rust, organic growth etc.) that can make the air unsafe?

Do the other gases of air in the tank change concentration? (Nitrogen, carbon dioxide, argon)

Are there any scientific studies on this?

 

[wedivebc]

There was a thread like this year ago and the upshot was the tank would weaken and probably explode before corrosion had consumed enough oxygen to become hypoxic. I would say there is not practical shelf life on a

 

[DevonDiver]

When you get a fill, be sure to confirm what the 'best before' date is. This can vary from store to store, depending on what air they use to fill. I prefer organic air, without artificial preservatives - my body is a temple. The downshot is that organic doesn't last as long in storage.

You can also improve shelf-life by refrigerating your air. It's amazing how many people overlook this. If the air is going to be in storage for a very long time, for instance beyond 2 months, then you can always freeze it. However, once thawed, don't refreeze it again. If you like to plan your diving a long way in advance, just get frozen air from your LDS.

I don't see much point to buying the expensive 'imported air' that some people claim is much nicer. Gas imported from the Himalayas, Artic or Amazon regions has a ridiculous price tag, but if stored for longer than a few weeks will just lose all its flavour.

Locally produced 'free range' air is more than sufficient, unless you're rich. Farm produced is an adequate compromise. I do avoid mass-produced factory air though, as it's not so healthy. Just look for the 'free range' sticker at your LDS and you'll be fine.











Also these threads are helpful:

http://www.scubaboard.com/forums/basic-scuba-discussions/254495-scuba-tank-storage.html

http://www.scubaboard.com/forums/general-scuba-equipment-discussions/353426-bleed-old-air-tank.html

http://www.scubaboard.com/forums/tanks-valves-bands/404384-how-long-can-air-sit-tank-2.html

http://www.scubaboard.com/forums/tanks-valves-bands/2090-tank-storage-life-span.html

 

[Searcaigh]

Would not want farm fresh air really, it stinks of poo as any good farmer will tell you

 

[LowDrag]

Hey Devon,

Not that I am questioning you or anything but are you kidding about "organic air" or what??? I know I am new but my gullible meter is screaming at me...LOL!!! Do I need to recalibrate it or is this an early Aprils Fools joke?

 

[DevonDiver]

Yes, it was a joke. You killed the vibe now... shame on you

The links I posted are valuable though. I just couldn't be bothered to copy and paste my previous answers on the same subject. It was far more fun to create some bad photoshop

However, given some of the junk ideas promulgated by the scuba industry to make cash out of diver enthusiasm/naivety... I'm surprised that nobody came up with the idea seriously yet. LOL It's not much dafter than a 'nitrox' Spare Air.

 

[Jim Lapenta]

Andy is not kidding. I only use organic air from reliable sources. So that means no air fills from NY, LA, Chicago, or the shop that takes in their air in DC from the Capitol building. I also do not store air in tanks longer than 6 months unless it is the air specifically desginated for use after the apocalypse this year. Unless you have bugs or mold growing in tanks storing air for up to 6 months is no big deal. If they need to sit longer than that why do you even own tanks?

 

[LowDrag]

Yes, it was a joke. You killed the vibe now... shame on you

Oh CRAP!!! I guess my gullible meter was dead on and I should have realized that and played along...


Sorry man!!!

 

[reo]

I remember someone in Florida a few years back was selling bottled hurricane air--air bottled during a hurricane.

Ron

 

[reo]

Andy is not kidding. I only use organic air from reliable sources. So that means no air fills from NY, LA, Chicago, or the shop that takes in their air in DC from the Capitol building. I also do not store air in tanks longer than 6 months unless it is the air specifically desginated for use after the apocalypse this year. Unless you have bugs or mold growing in tanks storing air for up to 6 months is no big deal. If they need to sit longer than that why do you even own tanks?

I would use the Capitol Building air in a separate tank for my drysuit inflation gas. Cheaper than Argon, and a plentiful supply.

Ron