Please share tips for buying a used tank

[keeth1123]

I never intended to buy a tank this soon. Also I was going to wait to buy a HP steel. However, I came across an AL80 for $60.00. I have used an 80 on every dive and jist rented one for 15.00.

I'm pretty sure I'm going to go look and purchase this tank this weekend. Can you share insight on what to look for. Tank needs hydro and vip. Poster says it also comes with diving weight but gives no information.

Luxfer Sherwood 06a95 80cf

 

[Eric Sedletzky]

You'd probably be fine buying this tank. If it was pre 1990 then you'd have worry about the bad alloy but in this case you should be golden.

 

[snowdog61]

There's a thread on sustained load cracking and T6351 vs T6061alloy. this applies to mostly pre-1988 tanks (thinking it was for Luxfer rather than Catalina but check the article). Not sure where it came from but shops have set a no fill policy for tanks that are either pre-90 or more than 15 yrs old. Hydros with a VE (visual eddy current) stamp are typically required for the 6351 tanks (and even the older T6061 alloy) and even then will sometimes be denied by a shop. Steel tanks are a definite benefit in that area. There are different issues with steel tanks taking a permanent set during expansion under hydro but are rare. If you are in this for the long haul and do a lot of dives a good steel 100cf should be a good investment that will pay for itself. Worthington & PST no longer manufacture galvanized steel tanks so if you can find one for ~$200 it is a good investment. The tooling is still out there and I'm still waiting for someone to make a production run.

 

[halocline]

The tank is probably fine, but some dive shops will refuse to fill older AL tanks. You could try to insist that this tank is not made of the older 6351 alloy, even showing some reference materials that would prove it, but you might be talking to the wall. It really depends on the shop. If you can get it filled it's not a bad deal, but you can probably find a much newer AL80 for not a lot more.

 

[Littlerayray]

Before you buy it find out how much a vis and hydro will be then compare that to a steel 100cf with current hydro and viz if you're within 80 bucks for the steel then get the steel with current viz and hydro

 

[rongoodman]

You might want to make payment contingent on the tank passing hydro.

 

[2airishuman]

I've recently been going through this. Things to consider:

1) As noted above, pre-1990 aluminum tanks are problematic since many shops simply will not fill them or will require a visual eddy test at one year intervals, which costs enough to make these tanks uneconomical to own.
2) Consider the cost of a valve rebuild if the tank is out of hydro or has unknown history. These can be quite costly at a shop. I do my own but it's time consuming if done properly, and still requires $20-25 worth of parts if you replace the seat and the burst disc.
3) Consider the cost of new valves if your regulators don't match the valves now on the tank, unless you have an adapter arrangement that will work out for you.
4) You may have to pay for tumbling or internal shot blasting if mild corrosion is present, before the tank will pass hydro.
5) Any tank can fail VIP or hydro with internal corrosion on steel tanks being the most frequent source of problems. Galvanized HP tanks can fail hydro even if they look great.

I'm paying $20 for hydro plus VIP and $15 for internal shot blasting but I have to drive the tanks to the hydro facility to get that price. LDS prices are almost double that. Be sure the deal you're getting is worth it. Remember you can get a new AL80 delivered to your door with VIP and warranty for around $200 and an HP100 for around $300.

 

[Kharon]

One other thing to consider - how frequently do you dive and what will the break-even point be? At my shop I can rent a tank for $10 and get a fill for $7. That's only a net difference of $3/dive. I still have to go to the shop to get the fill. Additionally I have to pay for a vis every year and a hydro every 5 years. If I'm renting I don't have those expenses, nor do I have to deal with getting them done.

I'm pointing this out because I have two steel tanks (50cf & 27cf) and two ponies (13cf & 6cf). I wanted steel for the negative buyancy and so I could just pick up and dive. They are small because I tend to dive shallow and the lakes locally don't have good vis and nothing much to see even if it were good. I keep them because I have an ultralight canoe to get around on the lakes and they fit better than an 80cf.

I need a pony because I dive solo. If I were to do it again I think I would only have the 6cf pony. Having my own tanks, I can pick up and dive on the spur of the moment, but I don't do that locally very often. I do a lot of volunteer and comunity service diving and when I do that I rent 80's so having my own tanks doesn't do me much good there. I'm not convinced that all the added expense and logistics for inspections is worth it to have my own tanks.

 

[keeth1123]

So I was able to obtain a low pressure steel tank from my brother. I dropped it off today to get inspected and filled. He believes it is a 90cuft.

My new question is this

If I dive with a buddy who rents an al80 with 3,000psi and I have a 90cuft low pressure tank with 2400 psi, how do we determine the turn pressure? Will his gauge drop faster than mine since its roughly the same tank just less pressure? I'm sure I'm missing something here

 

[Littlerayray]

You could follow the tech rule and go by 1/3
Third out
Third back
Third reserve
Or you could follow the recreational rule of go up stream first then once whoever gets to 1/2 tank plus 500 you turn back so in your tanks case
Half of your full pressure would be 1200 seeing 1200 plus 500 is 1700psi so at 1700 psi you turn back and should be coming out of the water with the recommended and possibly more since you would be coming back with current