Identifying marks on CO2 cylinder

Anybody know how to read the stamped marks on a CO2 cylinder? I'm trying to determine the age of one so I know when it will need to be hydrotested.

One line I can read seems to say "TC3-ALM 124 T11.2K3". I'm guessing the ALM is for aluminum and maybe the T11 is the grade of the material. I'm thinking the 2K3 is for 2003, but that's a wild a$$ guess.

There are more characters if anybody wants to know.

I just take my cylinder to the welding shop and swap it for a full one. I had two steel bottles when I moved to Oregon and now have two aluminums. The guy at the welding shop was happy, as the steel ones aren't all that common any more and some of his customers insist on steel, and I don't have to worry about testing. I also take my propane tanks in and swap them whenever they get too dirty/rusty. It's $5 more than a refill, but cheaper than testing.

Crown Markings CO2 Sounds like the info you want isn't marked on the cylinder, unless it is less than five years old. In which case, the original test is also the current one.

Thanks for the link. Yer a lifesaver, dude.

I compared some of the other crown markings to the info on that web page and realized the tank was originally tested in '94 and there haven't been any tests done since. Whoever buys that thing is in for a surprise.

The welding shop tests any cylinder that might be overdue, so I know anything I get there is ok.

They do around here too. But if I bring in a cylinder that they didn't sell or exchange to me, they charge me for the test ($14 or so) if it's out of date. And they tell me that if it doesn't pass, they confiscate the tank and destroy it. Doh! All the money for the tank and test down the tubes.

I think different states and sometimes even different local governments enforce the laws differently. They're pretty strict in my area.

Most municipalities are going to have pretty similarly harsh required responses to a bad cylinder because such pressurized vessels are very dangerous when compromised.

However, it sounds to me like the retailer you are using isn't the best choice. I'd find a place that will do a one-for-one swap. That way you aren't 'out' anything when your cylinder eventually fails.

I just got a free tank from a friend of mine that I have to see if it needs testing also. It's a Coke tank so I have to scape off the label or they won't fill it. Also have to see when it was last tested. If it's too old(and I think it is) at least I got a free regulator out of the deal.

Before you get to be scraping, check with the local coke distributor about filling/exchange. I've got a coke container and they charge me a small fee for the co2 and swap the cylinder for me.

Of course, I also happen to set up a coke dispenser for a local SF convention so I have a 'legit' reason to get the distributor to fill my container.

kornkob said:

However, it sounds to me like the retailer you are using isn't the best choice. I'd find a place that will do a one-for-one swap. That way you aren't 'out' anything when your cylinder eventually fails.

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All of the retailers I've spoken with have the same response to me bringing in a tank. They're perfectly happy to do a one-for-one exchange if the tank has been stamped with a passed hydrotest within the last five years. If not, I must pay to have it tested. If it passes, they give me an exchange at the exchange rate (and from then on they take care of the testing). If it doesn't... they tell me "sorry" and send mine off to be scrapped. At this point, I can either "buy in" to a full exchange tank or walk away with my wallet empty for the whole experience.

2nd Street Brewery said:

It's a Coke tank so I have to scape off the label or they won't fill it.

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That doesn't always work either. I had a long conversation with a guy at the retailer I'll use and he said that some of the info in the manufacturer stamp can tell them who it was built for (if it's a big business, like Coke). If it's an obvious one, they still won't fill it.

Basically, the warning here is: make sure you take in a tank they won't question and life will be easy. If it needs a test or looks like it belongs to a business (has an owner stamp), things could get hairy.

Just wanted to follow up on this. I actually got two tanks from my friend. The Coke tank was one he got where he worked. He used to just bring it in an swap it out when it was empty so he never had a problem getting it filled. The other was an old style 20lb tank that he got from a local guy who had a business on the side providing CO2 to the local fire depts and such. I called him up to see about getting it filled and when I brought it out to him he just laughed. Seems they don't even make this style any more and it was last tested in 1986 Any way, since I came highly recommended he swapped it out for me anyway. $20 to fill and $20 to get rid of the old one. The Coke one has some gas still in it so I'll just use that untill it's empty.

california only lets me fill a tank if its been hyrdod within 5 years! talk about a shake down of $25.

DrewsBrews said:

Anybody know how to read the stamped marks on a CO2 cylinder? I'm trying to determine the age of one so I know when it will need to be hydrotested.

One line I can read seems to say "TC3-ALM 124 T11.2K3". I'm guessing the ALM is for aluminum and maybe the T11 is the grade of the material. I'm thinking the 2K3 is for 2003, but that's a wild a$$ guess.

There are more characters if anybody wants to know.

Click to expand...

looks like a canadian 20lb cylinder to me......

i think the line should read "TC3-ALM 124 T11.2KG"

TC3-ALM is the Transport Canada rating of the cylinder.

124 is the service pressure of the cylinder in metric bar units.

T11.2KG is the metric tare weight of the empty cylinder.


hydrotest dates are usually stamped close to the valve, with prior dates in a vertical column.

DrewsBrews said:

They do around here too. But if I bring in a cylinder that they didn't sell or exchange to me, they charge me for the test ($14 or so) if it's out of date. And they tell me that if it doesn't pass, they confiscate the tank and destroy it. Doh! All the money for the tank and test down the tubes.

I think different states and sometimes even different local governments enforce the laws differently. They're pretty strict in my area.

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I am a certified cylinder inspector but I don't do this job as my primary. There are only a few very good reasons for failing a tank. There are some tanks that I have serviced in the past that are 20-30 years old. Occassionally a really really old one comes in.

However, things like cracks in the threading, pits or rust in the tank, cracks, or bulges indicate a serious problem. An exploding tank can go through very thick concrete walls, blow off an arm or leg, and generally kill and maim very easily.

It is not standard practice across the US to destroy failed hydro's (because the tank expanded and then did not contract again). Often the tank will just be stamped with a series of X's to indicate the failure and the tank will be returned. However, you won't be able to get it filled.