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Thread: Old air?

  1. #1
    Grouper
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    Old air?

    I hate to admit this, but my last logged dives were on 5/20/10. I finally have time to go diving next week, and I have 6 tanks in my garage full of air from last year. My LDS said that I shouldn't use air over 6 months old; is this true? I can understand that issues could arise from nitrox mixes in corroding steel tanks, but these are all filled with regular air (3 lp 95 steel tanks, 2 al 80's, and an LP 120 that I probably won't use). Can I safely dive the existing air before taking them in for this year's vis inspections? Professional opinions or research citations would be appreciated.

  2. #2
    Megalodon
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    I'm not a pro, but unless someone can quote a study that I haven't found, I'd say go ahead and dive the tanks. IF: the tanks had air from a reliable source and you trust that source. I've dove 8-9 month old air a number of times with no problems. I did a pool dive with 3 year old air once and had no noticable odors or problems.

    I once saved a man in Wichita just to watch him dive...(inventor)

  3. #3
    Shark snagel's Avatar
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    I don't have any scientific data to draw on, but I wouldn't have a problem using these tanks. I guess the question is, does the air "go bad". Thinking through this - how? If it is a sealed environment, nothing can get in. Maybe if there was water in the tank and then maybe mold could grow. That is a stretch in my mind because the tank is under pressure. If that could happen, it could happen very quickly and would be an issue that I'm sure we would hear about.

    Like you, I would like to see some "real data" backing this up. Did the LDS give any explanation?

    Snagel

  4. #4
    Grouper
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    I have used are that was 30 years old. No problem with air that is just 1 year old. Air does not have an expiration date.

  5. #5
    Barracuda Founding Member
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    If you are worried, the ONLY problem I can think of would be if it went hypoxic due to rust on the interior of the tank. Check it with an O2 analyzer and if it is OK, dive it. If not, get a visual because you probably have bigger issues...
    Flatliner
    aka Robert


    On the road to Grand Master Spammer...

  6. #6
    Grouper Founding Member
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    I had 2 tanks full of 32% that were a year old. I just checked the % again and used them with no problems.

  7. #7
    Grouper
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    I see no problem with diving the "old air", I would use them. As mentioned above there might be issues if your tanks have problems.
    Too many people miss the silver lining because they're expecting gold.

  8. #8
    Grand Master Spammer Founding Member
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    Vercingetorix's Avatar
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    Are the tanks still within in viz inspection? If not, get them inspected and new air will be added.
    rick

  9. #9
    As Flatliner and tc_rain said, check the air with an analyzer. If it is 20.8% oxygen then it is fine. If the level of oxygen in the gas is a little lower, put a clean, white cotton cloth over the valve so the air must pass through the cloth. Let some air out and check the cloth for a stain. No stain and cloth smells fine, use it. Get them visually inspected if the oxygen levels did drop a little. Could indicate an error in the analyzer or rust in the tank. If the oxygen levels have dropped significantly, don't use it. Get the tanks inspected before any use.
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  10. #10
    Shark
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    someone found old tanks (from the 60's i think) and some scientist was excited because he could test the air form that decade. I am likely to have my numbers mixed up but I remember the story and if it was on the internet it must be real...so if there is an internet geek out there like vercingtorix or scubastud I;m sure they can come up with the real story!!!
    God is good, no matter what!!

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