What to look for on used tank?

[Saltwater Junky]

Came across this thread... Thanks to all. I've been looking at a used tank, but now have considered all things and have decided not to but it.

 

[RonFrank]

You will need to weigh the factors before making a purchase. A older used tank can be a bargain, or a PITA resulting in purchasing junk, and then attempting to salvage the purchase which may not be possible.

I am assuming you are looking at AL80's.

Any tank made after 1988 in current hydro is likely safe. Tanks made after 1988 out of hydro are a little bit of a risk, but generally safe. If it is out of hydro, remove the valve, and inspect the inside for pitting and rust. If the tank has been stored empty, make sure you remove the valve and inspect it regardless of if in hydro or not.

You have to weigh the cost of the tank against the cost of new. If you are paying $150 including a new hydro and vis, it's not really worth it to purchase used IMO. You are only saving $50 if that.

I purchased a couple of used tanks in hydro, and vis a couple years back. They were also Nitrox certified, and I think I paid about $175 for two tanks both made in the late 90's. Renting is certainly a viable option, but it depends on the terms of the LDS, and how convenient it is to pickup, and return the tanks. In my case, the closest LDS is about 35 miles, and if I rent from them I have to return the tanks the next day or get charged a second days rental. So I purchased tanks as it was just too inconvenient to rent, and more so return in a timely manner based on the distance to the LDS, and where we often dive.

 

[millersacre]

you mean used tanks with lots of sticker on them don't mean they are experienced?

 

[halocline]

After looking around for a decent used AL80, I can say with authority that I never found anything worth considering for anything even close to $40....I paid $130 at a LDS with VIP and 4 years of hydro. (Tank age 6 yrs) A new AL80 here with tax is probably over $230; the best online deal I found was $150+ shipping, VIP and a fill when it arrives. (close to $200)

Maybe the San Antonio market is particularly tough, there aren't alot of local divers so there's not a good used tank selection. Ebay seems terrible for AL80s, all really old, high shipping, and possible problems getting it filled.

 

[Doc Harry]

If Aluminum created prior to 1990, you need to do some research. There are several batches that the DOT issued a warning about. Please see the DOT warning. Some tanks prior to 1990 ( made by Catalina) are not listed in the warning, however, your LDS may still refuse to touch them. My LDS will continue to vis and eddy test, the Hydro shop will not. I suspect they are refusing to buy the eddy tester. Apparently, after the warning was issued, DOT is requiring the hydro shop to eddy test these tanks.

The tank is one issue, the valve is another. I still use steel tanks made in 1956, so tanks & valves should last a long time. Should the valve fail, another $50 or so to replace. The valves on my steels can not be replaced.

Buyer beware. Many people are dumping their pre 1990 aluminum tanks on unsuspecting folks. Get the tank codes and talk to your shop before buying. On the other hand, I have bought several used tanks with no issues. If there is no air in the tank, that is a warning flag for me. THe tank needs to have some pressure to prevent becoming contaminated.

Happy Shopping - Tom

This alloy in question is 6351. It is subject to cracking, which is why annual eddy current testing is required. But a 6351 alloy aluminum cylinder that passes an annual eddy current examination is just as good as a cylinder made from the current 6061 aluminum alloy. Somewhere in 1988 to 1990 time frame all scuba cylinder manufacturers went to the 6061 alloy exclusively.

There is no logic or scientific data to support an decision by an LDS to refuse to fill a properly certitifed 6351 tank. If it has passed hydro and has a valid annual eddy current and visual inspection, then it is a good tank. Why do you think they run all those tests?

I would agree that people are DUMPING their 6351 cylinders on unsuspecting people. You need some kind of guarantee before you buy a pre-1990 tank.

I looked into a pre-1990 aluminum cylinder on eBay from "nj wreck diver." The seller REFUSED to offer a money-back guarantee if his cylinder failed hydro, eddy current or visual inspection. Without such a guarantee I would not buy a pre-1990 aluminum tank.