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How long is air good for in a tank?

Discussion in 'Tanks, Valves and Bands' started by Phillip, May 21, 2003.

  1. Phillip

    Phillip Angel Fish

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    This may be kind of a dumb question but aside from the limitations of the tank's structure (cracking, etc.) how long can you leave air in a tank and still breathe it? I don't know what would change about the air. I forgot that my tank was still full from late last summer. Would it be best to empty it and have it refilled before diving or is the air okay? I have all the inspections up to date. Hydro and visual were done last July. Thanks, Phillip
     
  2. Groundhog246

    Groundhog246 Loggerhead Turtle

    # of Dives: 100 - 199
    Location: Kitchener, ON
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    Much like water left to sit, air does go stale. I'd let a lot out (500PSI) and get a fresh fill (of course I don't pay for air at my LDS). Let it out slowly to prevent condensation in the cylinder.
    My LDS recommends reducing pressure to 300 to 500PSI for long term storage to reduce the stress on the cylinder. I generally get my inspections done in the winter (Feb/Mar) when the LDS is not busy and I don't need them for next weekend (they're used most weekends all summer). I get just enough air fill to keep impurities out and then fill before I start diving again in the spring (about 3 weeks ago).
     
  3. FredT

    FredT Loggerhead Turtle

    # of Dives: I'm a Fish!
    Location: The remains of the MS Gulf coast
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    3 years is not unreasonable, 5 years is possible assumin you keep the tank in hydro.

    Personally I'd sniff any tank over a year or two old with an O2 sensor to confirm oxygen content is unchanged from when it went in, then use it if it passed both that one and and Mark I Nose odor test.
     
  4. runvus4

    runvus4 Barracuda

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    If the tank was clean and the air going in was clean, then the air should remain breathable for a long time. As an air fill is only a couple of bucks, if you have any concerns, rather than risk your life/health on the opinions of armchair pundits like myself, I'd dump the air and get a new fill.
     
  5. Uncle Pug

    Uncle Pug Swims with Orca ScubaBoard Supporter

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    Phillip I think the question we all need to be asking is,"Are you stale?"

    I mean... no diving for a couple of days and I start to get real cranky... a month without geting wet and I would be unbearable... but almost a whole year?!?!

    Inconceivable!!!
     
  6. FredT

    FredT Loggerhead Turtle

    # of Dives: I'm a Fish!
    Location: The remains of the MS Gulf coast
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    ANYTIME a tank contains questionable quality air it not only needs to be dumped, it needs to be CLEANED before it is used! Clean dry air in a tank is good indefinitely. If it's not good SOMETHING is wrong in the tank and a visual and full valve service is in order at the bare minimum.

    FT
     
  7. drbill

    drbill The Lorax for the Kelp Forest

    # of Dives:
    Location: Santa Catalina Island, CA
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    If it is a steel tank, I would think there would be a small possibility of oxidation which could reduce O-2 content. However, I'm not a chemist so I don't know if this would be significant at the levels that might normally be encountered in a tank that received a visual less than a year ago.

    Dr. Bill
     
  8. Phillip

    Phillip Angel Fish

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    Yea, my life has been kinda busy. Time to get back in to it.

    Thanks to all who replied. -Phillip
     
  9. Uncle Pug

    Uncle Pug Swims with Orca ScubaBoard Supporter

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    I should have included a ;) in my post... I was just kidding you.
     
  10. runvus4

    runvus4 Barracuda

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    That is true. I do think that the air is most probably good since he stated that the tank was in current VIP and hydro, and I would think that he had got his fill last year from a dive shop operation that pumps clean air.

    My point was more to the fact that he is talking about his own life support equipment. It's good that he is asking for more information to make an informed choice, but in the end it's his life and his personal comfort levels. No matter how right, knowledgable or correct the polled opinions are, if he is not personally comfortable, then "call the dive" so to speak instead of doing a "trust me" dive. For a couple dollars, if I wasn't sure about the gear/air, I would easily err on the side of paranoia and caution.
     

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