Odd ball tank

[Ron]

http://www.ebay.com/itm/Vintage-1961-Sc ... 3a989f6f90

This is a 1961 dated PST 80 cubic foot tank. It isn't a USD one, because those are stamped USD. Anyone remember tanks like this BITD? I cannot find it in any catalogs.

[2THDIVR]

I think it might be a 94 cf
Had a friend that had a couple of them years ago.
they were really negative

[Ron]

A friend from the forum suggested that this is a 90 cubic foot US Navy tank. I know Captain Tom has some of these. I have never seen a USN cylinder without the "NON MAGNETIC" stamp on it. Have you guys seen USN 90 cubic foot cylinders that were not EOD ones for regular Navy scuba diver use? Our forum friend is right in that the only tanks that I have seen with WP and TP stamped on them like this are USN ones. Has anyone seen anything like this before? I asked the seller for more pictures. Will they all be marked US Navy? I have reviewed the MIL-SPEC for the nonmag cylinders, and they mention that they all have to be marked as nonmag. The spec also mentions that the cylinders all have to be marked with the measurements for hydro and so on. I guess I have to ask if there were aluminum cylinders made for the Navy that were not nonmag spec? If so, is this one of them?

[captain]

The size along with the stampings seem support it being a Navy aluminum 90, but the shape of the top curve doesn't. The curvature of the top and bottom are equal on the Navy tanks. The top of this one looks more like a steel tank. If interested have the seller put a magnet on it to see if it is AL.

[Ron]

Good call Mr. Tom, I will let you know what I find.

[Ron]

It's aluminum. It has to be a USN tank then...right? I don't think anyone else made aluminum tanks during the early 60s. It has to be an early 60s tank or it would be 1/2". Also, the earliest hydro stamp is 1961.

[antique diver]

I think those had a plug in the bottom hemisphere. Probably blended in and fairly well hidden, but you might look closely to see if you can find one. I think they were spin-shaped with the bottom smoothed off and plugged... maybe threaded at that end too? I saw a couple of these long ago, but since they didn't have a current hydro I declined to fill them.

I don't know if that's bad, but there were at least some rumors about their safety, related to limited life expectancy. 60's aluminum does worry me somewhat, given the originally unforeseen problems with the 70's "last-forever" 6351 alloy tanks.

Tom, can you add some facts or info on how safe these things are? Meanwhile I will contact my friend at Firehouse Hydro to see what he knows. It could be on the list of expired exemptions. I look forward to learning more.

[crimediver]

Another vote here for a non-mag tank. The valve has surely been replaced and the cylinder was probably on a set of doubles when it started out. I have never seen a non-mag valve that was not a j-valve double manifold.

The only cylinders I have seen that were round bottom aluminum have all been USN non-mags. I also did not see a DOT number, etc so I think that would make it a non-mag USN tank and someone put another valve on it.

The Green Beret VIP sticker shows that there was a tangible military pedigree. It is possible that an Army special forces diver may have had a need for a non-mag tank or an enterprising Special forces soldier simply liberated it from the Navy as they were not maintaining a proper watch and they needed to be taught a lesson.

[Ron]

I agree but why doesn't it have any of the required mil spec markings?


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[captain]

The set I have are from 1967, they are stamped with working pressure, test pressure and original hydro test results, non-magnetic, internal volume. serial # and DOD acceptance stamp.
The only issues I have heard about are leaks from the plug in the bottom. I had them hydroed and the results matched the original results stamped on them.
I have no actual knowledge but I believe they were retired when commercial aluminum tanks came on the market and the switch to rebreathers rendered them no longer needed. They were listed as 90 cu/ft but are closer to 80 cu/ft. I have no concerns with mine as they appear to have seen little use.

[Ron]

This one has only working pressure, test pressure, and the PST name and serial number. It interests me, and if I could be reasonably sure that it would work well then I would use it. As long as it is structurally sound.

[ovalis]

I believed it to be a USN aluminum tank as well. I ended up buying it. I have a couple of these tanks, but non of mine have the plug in the bottom.

[Ron]

Thanks for the reply Mike. Can you detail what you find on this thread if you don't mind? I know that you are a busy man, but it would be cool to store the information here.

[ovalis]

Ya, I'll let you know the details of it when I get it and compare it the others I have.

[Superlite]

Just re-read and I noticed the comment about a plug in bottom of cylinder . That is a definite indication of a Navy cylinder. That is a give away, only Navy cylinders had a bottom plug. That is due to those particular cylinders were spun, not extruded.