US Diver Tank ID Help

[Waterskier1]

I'm trying to ID a tank. It has a US Diver "Aqua-Lung", yellow in color, with J-Valve. The decal/sticker from US Divers is a Black circle and shows a single tank with a double hose reg in the center, "aqua-lung" (in quotes) across the middle, with "U.S. diver" across the bottom. It has the markings 1CC-1AA2250 which I understand is the Interstate Commerce Commission (before DOT marking) and it's a steel tank rated at 2250 psi. The only other info I got from the seller is that it is 26" top to bottom (not including the valve) and 22" around. I didn't get any other hydro or s/n stampings from the seller.

That means it's about a 7" diameter tank, 26" tall. I've read on here that 7" (maybe really 6.9") tanks about 25" tall are LP-72s. I can't find any data sheets for LP-72s (2250 PSI). All I can find are MP-72 (3300 PSI). Further, the only tanks I can find on current reference charts that are 7" by 26" tall are Faber and OMS LP-85s.

Is an LP-85 only 1" tall (longer) than a LP-72?

Is that some way I can tell for sure what size this tank is? We know it's old, since it predate the DOT marking.

 

[DA Aquamaster]

It is almost certainly a steel 72 made prior to 1967 as steel 72's are 6.9" in diamter and are about 26" tall. If it has a 3/4" valve it was most likely made between 1959 and 1966 and the date can be established by finding the original hydro test date on the tank which will be in a month/2 digit year format with the test facilty symbol in between the two.

I am not sure when US divers tanks started showing up with an epoxy liner, but it is possible your tank has one. If so it will have to be removed to allow a proper visual inspection as the liner used was dark brown in color and tended to hide rust underneath. Removing the liner is a real bear and requires lots of tumbling.

 

[Tom Smedley]

I bought one in 1971 that had the epoxy lining. The dive shop that sold it to me claimed it was a new process. The gamble that you take when you buy these tanks unseen is rust inside. I ahve collected about five of them and have lost on one that was badly pitted. I really love the buoyancy characteristics and dive with them often. Don't pay a lot for it unless it is really cherry.

 

[Waterskier1]

Thanks guys.

Can you provide any more info on the LP-72s, such as Empty weight, Buoyancy empty and Buoyancy full? As I said above, I have found many charts for AL and Steel tanks, but none list the LP-72.

I'm guessing the age is what gives it away? Or the brand? Otherwise, what lead you away for the LP-85 which is almost the same dimensions (within what one might read with a tape measure)?

Is there an easy way to determine if it has a 3/4" valve by looking? That is, without removing the existing valve?

I've been reading such great things about the LP-72s as far as buoyancy characteristics, I'm wanting to use a couple for doubles. I don't need lots of air for most of my diving, but do want the redundancy, and experience diving doubles.

 

[Scared Silly]

Somewhere I have the specs but they about 1 negative empty.

It is a 1/2" NPT valve it will be 1/2" in diameter and will be tapered. You will likely still see threads. There will probably be teflon tape around the threads.

A 3/4" seals based on the o-ring (1/2 seals based on the threads) so no threads will be visible.

 

[Waterskier1]

Somewhere I have the specs but they about 1 negative empty.

It is a 1/2" NPT valve it will be 1/2" in diameter and will be tapered. You will likely still see threads. There will probably be teflon tape around the threads.

A 3/4" seals based on the o-ring (1/2 seals based on the threads) so no threads will be visible.

Makes perfect sense. Don't know why I didn't think about tapered threads sealing only by thread contact, and the (scuba usual) 3/4" seals using O-Rings. Especially after all the trouble I had with a pony tank o-ring extruding.

If someone has the "spec" empty weight figure for these tanks, I'd really appreciate them posting it so I can compare to AL 80 and LP 85 and HP 100s.

 

[captain]

Empty they are about 28 to 29 pounds. Empty buoyancy is anywhere between -1 and + 1 depending on manufacture. Most U S Divers were made by PST. The ICC is a give away as to age. No newer LP or HP tanks will have ICC stamped on them only DOT. The job of regulating the transportation of hazardous materials was transferred from the Interstate Commerce Commission to the newly formed Dept of Transportation in 1967. The Interstate Commerce Commission was eliminated in 1995

 

[Waterskier1]

I got a bit more info from the seller. The original hydro is 04/62 with a Norris Industry "N" with a diamond around it between the "4" and the "6". I am assuming it is Norris by the description of an "N" with a diamond. He removed a valve and it does have an O-Ring. The last hydro was 2001 by the owner. He has had to remove the valves (and hence the air pressure) due to transporting them during household moves since then. He looked inside and said it looked good, with a bit of "freckles of rust" (his term, not mine) on the inside surface.

Unless you someone knows a good reason not to get these (being Norris and 1962) I think I'll pick them up - for $15 each. Hopefully I can find someone to do a brief visual to let if it looks like they pass, before I pay for a hydro.

 

[captain]

I got a bit more info from the seller. The original hydro is 04/62 with a Norris Industry "N" with a diamond around it between the "4" and the "6". I am assuming it is Norris by the description of an "N" with a diamond. He removed a valve and it does have an O-Ring. The last hydro was 2001 by the owner. He has had to remove the valves (and hence the air pressure) due to transporting them during household moves since then. He looked inside and said it looked good, with a bit of "freckles of rust" (his term, not mine) on the inside surface.

Unless you someone knows a good reason not to get these (being Norris and 1962) I think I'll pick them up - for $15 each. Hopefully I can find someone to do a brief visual to let if it looks like they pass, before I pay for a hydro.

For $15 each you can't go wrong.

 

[DA Aquamaster]

Freckles of rust could just be scattered flash rust or it could be a bit thicker and covering scattered pits.

You will probably either have to or will want to have them tumbled. Either before or after the hydro test. Before if it is anything more than flash rust as it has to pass a visual inspection as part of the requalification (hydro) process, but tumbling after will remove any flash rust that may develop during the hydro test.

But as noted above for $15 each, you can't go wrong.

Also as noted above, the buoyancy traits of steel 72s varies a bit by year and by maker but ranges from from +1 to -1 when empty.

An LP 85 would have a 2400 psi service pressure rather than 2250 psi. One thing to be aware of is that the steel 72 holds 71.2 cu ft at 2475 psi (2250 psi plus 10%) and holds about 65 cu ft at 2250 psi.