40+ Year Old CO2 Tank

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Jan 23, 2013
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A friend of mine gave me an old 20lb CO2 tank that has a tank date of 1979, so it is likely to have been filled years before that. It seems pretty full and I was thinking of using it. Any dangers of using it? I know CO2 doesn't go bad, but can the tank corrode causing impurities in the gas? I don't know where the tank came from, so perhaps there is risk of the unknown?


Well-Known Member
Dec 17, 2014
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The Island
technically its possible there could be some rust on the inside of the cylinder. i'd take off the regulator and just blow some out into a clean towel or even on a wall somewhere out of sight. but DONT GO CRAZY. thats high pressure in there. just crack it open enough to get good flow. if there's rust you'll see it on the towels or the wall. if not, you're good to go.

now when its time to get more co2 you're gonna have to get it recertified somehow, as its well beyond its 5year certification period.

the easiest and cheapest way is to find a homebrew/wine or hydroponics supply place and see about swapping it for a full tank. my local brew shop doesnt bother to check the date. so i never have to pay if i have an out of date tank. but thats unusual for a brew shop. and im not even sure the hydroponics guys check either, but they only swap aluminum and those tend to be newer than steel. most places do check, and charge. if you can find one that just swaps and doesnt check, you're golden.

but if they all check, you can add welding and gas supply places to the list. then call your down your whole list and ask ---
---1)if they swap steel 20# tanks?
--2) if there's a recert fee?
--3) how much for 20# food grade co2?

worst case is that everyone charges to recert so you'll just have to pay to have it recertified, which shouldnt be more than like 40-50bucks, tops.

you dont list where you're located so can only tell you my situation. homebrew shops are like $4-5/lb for co2. crazy expensive. but the hydroponics shops will swap a 20# aluminum for $26, about $1.25/lb. huge difference. and its all food grade around here. somebody in texas just swapped 20s for like $40 i think, maybe near dallas? cant recall.

it takes a bit of research, but once you've got an in-date tank you can just focus on whoever sells the cheapest gas and do your swaps there.


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Jan 18, 2020
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South Bend
Don't open any tank without a regulator attached, period.

If it were me, I'd call gas supply stores, explain exactly what you've got, and ask them if they'll swap tanks (or retest and recertify the one you have.) If they don't want to take an old tank because it's unsafe or unhygienic or otherwise not fit for long-term service ... do you really want to use it yourself?