Scuba 72's

[Daniel379ba]

Hello, I just purchased two AL 72's from craigslist for 30 dollars apiece and I was wondering if I made a rookie mistake.
(Buying used, Is not the mistake I'm asking about, I'm having them Hydro'ed + Eddycurrented at Fire King and Vis'ed at Underwater Sports in Edmonds)

The mistake I'm wondering if I commited is picking the right tank.
Was going for a size 72 stupid? From what I've heard I use air pretty slowly, On a 45 minute dive somewhere I've never gone before, averaging around 40-50ft I started with 3000 and ended with 1100, so only 1900 used in 45 minutes...

I'm frusterated/nervous that I didn't do proper research before hand because now I'm seeing...

Bad Alloy comments
Size restraint = 2415
"Floater of +11 pounds"???

Heres all the bad comment's I've been seeing, and I'm not sure if they are the same tanks (the one I bought and the ones they're talking about)

http://www.scubaboard.com/forums/archiv ... 47960.html

Here's what I bought, the two silver ones on the left,
http://seattle.craigslist.org/tac/spo/3761548511.html

What the cylinders say on the top are
3A
DOT-SP6498-3000
P13098 USD

and on the other one...

3A
DOT-SP6498-3000
P1261 USD
Something with "A....4....73..."

So I guess what I'm wondering is, are the comments I was saying/seeing above/earlier true?
What is the size capacity? On http://www.deep-six.com/page66.htm I see "Aluminum 72 can have a max of 3000" and if true that's perfect but what about the comments from that other forum I posted: ...
"In 1971 they made the AL72 and the working pressure was 2475 psi."

Anyways, Sorry for the noobish questions, I feel terrible if just wasted alot of money.
Please let me know if I made a bad decision, thanks.

[Desert Diver]

Hi Daniel, They are 3000# cylinders. Almost certainly the alloy that can have the sustained stress cracks. So long as they are tested and you can get someone to fill them you are probably alright. I didn't find bouyancy info on those but new AL72-3000# are about the same as AL80s.

Good luck

[Dusty2]

Most of the time when you hear of people talking about 72's They are refering to LP steel 72's which the tech bunch like for doubles. Not aluminum.

Sorry but yes you made a noobe mistake. Very few people use aluminum tanks up here and tanks that old are never a good bet especially when aluminum and any tanks you buy that are way out of hydro are not a good bet especially for a noobe that doesn't know what to look for. You were ok with the Original $60 because most of us waste far more than that. However I fear the money it will cost to get them back will make them a very expensive investment.

Sorry

[Nwbrewer]

Most of the time when you hear of people talking about 72's They are refering to LP steel 72's which the tech bunch like for doubles. Not aluminum.

Sorry but yes you made a noobe mistake. Very few people use aluminum tanks up here and tanks that old are never a good bet especially when aluminum and any tanks you buy that are way out of hydro are not a good bet especially for a noobe that doesn't know what to look for. You were ok with the Original $60 because most of us waste far more than that. However I fear the money it will cost to get them back will make them a very expensive investment.

Sorry

He's probably in better shape than most of us, there's a good $30 worth of scrap aluminum there!

Daniel, it's probably not worth the effort you'll go through to get two rather small tanks that will be inconvenient to get filled.

[sitkadiver]

OK, this is all an edit.

Some time ago, DOT had the 3A designation change to 3AL for aluminum tanks, so I'm assuming you know what you've got.

There were 2 varieties of the Al 72's. The older 2475 psi one is the bouyant POS, the longer 3000 psi AL 72 was made by Hymark to negate the positive bouyancy of the older, lighter tank.

They didn't stay on the market very long becuase the bouyancy issue was moot when compared to a steel 72. Plus, all the parts were available for twin steel 72's. The Final chapter of course was the introduction of the AL 80, which was simply more marketable.

As long as your tanks pass eddy current testing and hydro, they should be fine. When they do go in for hydro, you can expect the hydro tester to restamp the tank 3AL above the 3A.

Good luck.

[Daniel379ba]

So what I got was the older 2475 one's because it's not made by Hymark?


Edit:
Or is it the 3000 as he said earlier?

Because if it is 3000, I'm personally fine getting them tested and if they pass I see nothing wrong using them, because I got a tank , that hold's enough air for me, and if testing goes well, than I'm safe and it was for a very good price. Getting Hydro, Eddy, Vis still = cheaper for 2 than one new online, atleast from what I've seen

[Jeff Pack]

With tanks that small, you'll be calling dives early, unless you breath like a girl.

[CaptnJack]

Those are AL80s, true capacity 77cf. They are 40 years old.
They are made from the "bad" alloy and Underwater Sports won't fill them.

Fire King will hydro them, and eddy current test them for a hefty extra fee. And assuming them pass all that, the US Dept of Transportation will bless them as "safe" but most shops will not fill them anymore. I doubt Underwater Sports will bother visually them since as a company policy they don't fill aluminum cylinders older than 1990 (I think).

[Nwbrewer]

Those are AL80s, true capacity 77cf. They are 40 years old.
They are made from the "bad" alloy and Underwater Sports won't fill them.

Fire King will hydro them, and eddy current test them for a hefty extra fee. And assuming them pass all that, the US Dept of Transportation will bless them as "safe" but most shops will not fill them anymore. I doubt Underwater Sports will bother visually them since as a company policy they don't fill aluminum cylinders older than 1990 (I think).

That was my point. By law, they are "safe" but few dive shops are willing to take the chance. Considering how cheap you can pick up post 1990 al80's on CL, I wouldn't invite the headaches.

[Daniel379ba]

Alright!
I just went on a "knowledge raid" trying to figure everything out so I made a few phone calls and here's what I learned.

From FireKing...
"Any aluminum tank can have cracking and that's what the Eddy test is for. You could go and buy new $500.00 Aluminum tanks and still have the same problem. When they were made in 1973 was when they just started using Aluminum. They were very careful and these tanks are much better taken care of compared to during the 80's when they sped through them because they had gotten checked off." My tanks are looking good right now and if they don't past any of the tests or I encounter any problems he said he will hook me up with tanks for very cheap. He was a very nice employee, knowledgeable and helpful.

From Underwater Sports...
They won't fill them because they're from 1973.

From Lighthouse...
As long as they past Hydro and Eddy they will fill them and they also offered to trade them need be.

So right now, I'm at peace.
If the tanks have trouble, I have a replacement option.
If I need to sell them, I have people to help me with that.
If I need any tests done, FireKing is the place to go.
If I need air filled, I can go to light house.

I don't know how to verify their size at the moment but what it looks like is that there 3000 (from what your guy's are saying, which might change knowing they were made in 1973.)

But if there not, I'll just use a double rig, and if they are 3000, that's perfect, because that's what I've dived with 99% of the time.

Thank you for all the help and if any of you need any convincing, Fireking is one of the best places to go to :-).

Cheers!

[CaptnJack]

I had some eddy current tested at hydro by Fire King maybe 4 years ago. The price on top of the hydro costs was insane ($15 or 20 I think?). Spending alot of money on testing these is poor economy since they are likely to fail sooner rather than later so all those hydro, eddy current and VIP costs are wasted. At least one is 40 yrs old afterall.

They are AL80s, you see these older tanks for sale on CL all the time. Don't get snookered and pay more than a pittance.

[Jeff Pack]

Do you really want to be so limited where you can get fills? Because that's what you are getting. Only a few shops will fill them. For abit more you can get better tanks, and have them filled anywhere. Later AL80's show up on CL all the time. A guy in Oregon is selling late hydro Luxfer AL80's for 95$ and brought them up here for my dive buddy.

[Daniel379ba]

Yessiree.

[Daniel379ba]

Well I just had a very discouraging conversation with a dive shop - I guess experiences like these are how you learn through.

[Dusty2]

One thing will learn over time is the information you get here is more reliable than you will get just about anywhere else. There is a vast knowledge base here both diving and all the technical aspects as well. We have divers here that have been at it since the seventies and have actually learned the hard way. With the exception of differing opinions as to the "Proper" equipment to use you will get unbiased and knowledgeable info that can and will save you bucks.

From my experience things on Craigs list tend to fall into 2 categories. Junk and some good deals. If they are truly good deals they won't last very long, especially tanks. We have several people that cruise CL all the time and if something good shows up it will appear on here unless they already snatched them up. Good deals on desirable tanks are usually gone by the time you call. :angry:

[elmer fudd]

Unless you're a collector of old scuba gear, the only old tanks I would bother buying would be galvanized steel LP72's. You can often get those cheap and in good condition and they have some good characteristics to them, (lightweight, near neutral, long). They're a little small for a lot of dives though. If you take your time and look around you'll find them for cheap, (I've paid as little as $10).

When you start looking at really old tanks there are a lot of potential problems. The alloy used to make your tanks is one of them. Some older steel tanks were only rated to 1800 psi. Others have some strange buoyancy characteristics, (Beuchat, Faber).

For most diving around here, I'd be looking for modern steel tanks like Worthingtons or PST's. HP100's seem to be the favorites.

[Dusty2]

With most divers around here you need to shoot for at least an hour. 45 min is a very short dive. I would recommend steel HP 100's for a starter tank and go from there. They are nice and compact and have good buoyancy characteristics and make good doubles when needed.

[Nwbrewer]

Daniel, your RMV is pretty good from what paul tells me, so you probably could do fine with 72's, but the issues is going to be having enough gas for you AND your buddy if something happens to his gas supply. Most of us don't have mouse lungs.

For your body size, an HP80 would be an OK tank, or LP 85's or something would be decent too. Those pop up on CL cheap every once in a while. If you're ever looking at something on CL you're not sure about, feel free to PM me or Paul, we won't snipe it out form under you or anything.

Jake