Educate Me About Buying Used Tanks Please.

[eelnoraa]

I have to say I have good luck with 6351 luxfer tanks. I bought 4 + weight belt for $20. 3 pass hydro and being used. Shops around me has no issue filling them. 1 of the 4 is lost by a LDS, otherwise could have been good as well. I still can't believe a shop can lose my tank, but that is another story.

 

[Bob DBF]

there's a difference between not knowing how to do their job and not wanting to waste their time dealing with special scuba crap when they have better things to do (like test fire equipment which actually pays the bills).

There is nothing special about a pre '91 scuba tank, if someone doesn't want, or is too lazy, to know their job better than I do, I'd rather not do business with them for my own safety regardless of their rationalization.

also, testing most "standard" tanks is easy. pressurize to 5/3 pressure and record the numbers.

Putting people trained that way right up there with tank monkeys, rather than technically proficient in their trade.


Bob

 

[Bob DBF]

I still can't believe a shop can lose my tank, but that is another story

I hope they got to buy you a new one for their inattention to detail.


Bob

 

[eelnoraa]

no they did not. they are known to be unorganized, but I didn't expect they can lose a tank. It was the last time I visited them

 

[halocline]

The issue with buying and owning scuba tanks is that you need to get them filled, usually at a dive shop, and dive shops can refuse to fill any tank, at any time, for any reason. Dive shops vary greatly in their knowledge of scuba tanks and willingness to fill tanks they either did not sell or are not familiar with.

Unfortunately it's not much better at hydro shops. You might think that they are uniformly knowledgeable about scuba tanks, being licensed, but you would be wrong. So the whole thing; buying, owning, testing, and filling scuba tanks is a big fat crapshoot unless you own a compressor.

With modern AL tanks there's usually not much of an issue; they basically always pass hydro, they don't rust, dive shops see them all the time and are comfortable filling them to 3000 PSI. Too bad they suck to dive with!

Older tanks are the problem, which is a shame because for shallow local dives, it's tough to beat a LP72, and they're cheap to buy. If you can find a dive shop that recognizes the appeal of these tanks and will fill them, they're terrific.

The way to buy steel tanks is to look inside them, with a good light, and have some idea of what you are looking at. It's not rocket science, it just takes a little experience to recognize the difference between surface rust (that can be a by product of hydro testing) and deep corrosion resulting from wet fills and/or sitting empty with moisture present. It's fairly unusual that any scuba tank that looks fine on the inside (and of course outside) will not pass hydro. It does happen, but not frequently. Usually if you buy a tank that's out of hydro, you can get the seller to agree to refund your money if the tank fails hydro. Then you're only out the cost of the test, which around here is about $25 at a hydro shop.

 

[kc9ljo]

Thanks for all the advice. I knew it was complicated but I had no idea just how complicated. We'll see how it goes.

 

[Jax]

Here is a good writeup on ebay on the aluminum tanks.

Danger Warning: Buying Aluminium Scuba Tanks

 

[2airishuman]

The issue with buying and owning scuba tanks is that you need to get them filled, usually at a dive shop, and dive shops can refuse to fill any tank, at any time, for any reason. Dive shops vary greatly in their knowledge of scuba tanks and willingness to fill tanks they either did not sell or are not familiar with.
[....]
With modern AL tanks there's usually not much of an issue; they basically always pass hydro, they don't rust, dive shops see them all the time and are comfortable filling them to 3000 PSI. Too bad they suck to dive with!

This. I found that I had to try several shops and then cultivate a relationship with the best of them, although my problem has been with short fills, not with outright refusal to fill a tank.

Unfortunately it's not much better at hydro shops. You might think that they are uniformly knowledgeable about scuba tanks, being licensed, but you would be wrong. So the whole thing; buying, owning, testing, and filling scuba tanks is a big fat crapshoot unless you own a compressor.

A problem with hydros on older steels is that many places won't stamp a + on the tank even if it qualifies. Some shops don't care and fill the tank as though there were a + anyway, some shops won't and then your LP72 turns into an LP66.

The way to buy steel tanks is to look inside them, with a good light, and have some idea of what you are looking at. It's not rocket science, it just takes a little experience to recognize the difference between surface rust (that can be a by product of hydro testing) and deep corrosion resulting from wet fills and/or sitting empty with moisture present.

Ideally, yes. The trouble is you need the seller's cooperation and you need to be able to get the valve off, which can be difficult without a tank vise especially for tanks that have been sitting. I can usually get them loose by hitting a wrench with the wood handle of a 2 pound sledge, but some sellers might be, um, concerned about that approach.

 

[rjack321]

A problem with hydros on older steels is that many places won't stamp a + on the tank even if it qualifies. Some shops don't care and fill the tank as though there were a + anyway, some shops won't and then your LP72 turns into an LP66.

Getting the REE to plus stamp a lp72 is basically impossible at this point. I'd be shocked if any hydro facility can plus stamp a 72. Mine pass via the 5/3rds rule but no pluses. I fill them to 2500 anyway.

 

[DavidFL]

I have two Catalina AL80s; one with original date 12/90 and one is 1/91; I have had occasional "swirl" where people basically told me I wouldn't be able to get them hydro'd and/or filled. The details are complicated but as one early poster said: Catalina (the manufacturer of my tanks) never built a tank with the "bad" alloy on any date. My local dive shop just got them hydro'd for me (5th or 6th? hydro in their lives) and they fill them routinely. If you end up with tanks that could be swept up in the "pre-1991" generalization about aluminum tanks and you want to get them filled away from your normal fill source, it's easy to download a PDF of the actual DOT written notice and store it on some cloud based service so you can retrieve it on your phone....I've had to do that exactly once, but in my case once they read the specific information about manufacturers I have been able to overcome the obstacle.