USD Tank Help

[Dave2]

Hello,
Someone had posted "vintage scuba tank" on Craig's list and I drove out to see it.

It wasn't quite what I was looking for and not quite vintage but I bought it all for $40 anyway.


Can anyone give me any info on the tank? The markings might as well be hieroglyphics to me.




The tank valve, pressure gauge, and 1st stage reg are US Divers also.



I'm hoping the tank valve is usable. That's the real reason I bought the set. Still looking for a steel 72 to go with my Waterlung Back Plate.

Thanks in advance,
Dave

[simonbeans]

You have an Al USD tank of the alloy that is questionable. Many of the dive stores will NOT fill them.
I have a couple of Sportsways 71.2s if you are interested. One has a 1/2" O-ring with J-valve and the other has a 3/4" O ring K valve. Both were hydroed in 2013. They are orange.

Your tank will make a nice wind chime.

Sorry.

Allan

[Dave2]

Thank you. I thought that might be the case. I'll take it to my LDS and see what he says. I want to test that SPG too.


Sent from my iPad using Tapatalk

[swimjim]

Looks like an old Al 72. Even if you could fill it, not a good tank. The first stage looks Aquarius. I definitely could be wrong on the ID, but I'm sure somebody will correct me. When you test the Spg, point it away from your vitals. I had a Nemrod gauge blow and hit the shop door a few years ago. Good thing I wasn't looking at it. May have improved my looks or maybe solved all my earthly problems in one blow. I suppose having made in Spain imprinted backwards on my forehead could be a good conversation starter. LOL

[Dave2]

Thanks Jim. Funny you say that, I even point my brand new SPG's away from my face.


Sent from my iPad using Tapatalk

[luis]

That is a 1972 aluminum cylinder. It was the first year that aluminum cylinder where offered in the US.

It is a 72 cu ft cylinder with a working pressure of 2475 psi. It was supposed to have the same pressure and air volume as a steel 72. It also had the same diameter.

That aluminum 72 was quickly replaced with the aluminum 80. I don’t remember seen them for more than one year.

The big difference is that this cylinder is a lot taller and it floats like a buoy. It was common to strap a 5 lb weight on the bottom to try to make manageable.

Also as mentioned above, this cylinder was made out of 6351 aluminum alloy. This alloy is susceptible to sustain load cracking and requires special inspection and special care during the filling process. I personally would not even consider trying to re-certify. It is not worth it.

I actually have one of those cylinders that my LDS gave me. It is just for display. I consider it one of the odd pieces of vintage dive gear that was a failure (due to its buoyancy). It is part of dive history and IMO, a conversation piece.

[luis]

Thanks Jim. Funny you say that, I even point my brand new SPG's away from my face.


Sent from my iPad using Tapatalk

I consider that very good practice. I do the same thing with any pressure gauge.


Yes, that is an Aquarius. It is a very simple non-balanced piston first stage. It can be easily serviced.

The second stage is the typical US Divers used in all of their regulator at the time. Actually, I just noticed that I can't see the second stage, but that is what it would be.

[Herman]

I will add a little, the tank does have some value, there is maybe half or more of your investment in it as recycled aluminum so don't just trash it. The J valve is prefect to use with your DA if you would rather not use a banjo and it will fit both old 72s and modern tanks with 3/4in openings. The Aquarius appears to be a later one with HP yoke. It is a very easy reg to rebuild and if I remember correctly, Bryan has service kits for it so it makes a good reg to learn DIY service. It's design is unique as it is one of very few piston designs that have an external adjustment for IP.
On the slightly down side, the BP is NOT well suited for DH use, it holds the tank off your back more than it should, placement is very important when diving DH regs. On the other hand, it is perfect for diving the Aquarius old school without a BC and IMO no BC diving is a must learn if you dive a DH reg. By the way, if the snaps on the BP harness are bad, they are easy to replace.

[Dave2]

Yes, that is an Aquarius. It is a very simple non-balanced piston first stage. It can be easily serviced.

The second stage is the typical US Divers used in all of their regulator at the time. Actually, I just noticed that I can't see the second stage, but that is what it would be.

Luis, Thank you.

It didn't come with the 2nd Stage. I was a little bummed but I'll survive.

[Dave2]

I will add a little, the tank does have some value.....

Thanks Herman.

I'll hit Bryan up for an Aquarius service kit soon.

I just emailed the guy who sold me the DA AM and he has an LP72 with a Sportsways valve. I'll pay the hydro and put this J-valve on it.

The BP has a few small cracks in it. They are not big enough to effect structural integrity, but it may be worth filling with some black 2-part epoxy.

Thanks again for all the great info (good and bad).

Dave

[simonbeans]

Double check on the J valve size on the Sportsways valve. Many were 1/2" O ring. The one on the USD Al is a 3/4" O ring.

Sand Lake? I grew up in Blissfield. Dove a lot in Allen Lake and Silver Lake over in the Ann Arbor area.
That was a life time ago.

[simonbeans]

Double check on the J valve size on the Sportsways valve. Many were 1/2" O ring. The one on the USD Al is a 3/4" O ring.

Sand Lake? I grew up in Blissfield. Dove a lot in Allen Lake and Silver Lake over in the Ann Arbor area.
That was a life time ago.

[Dave2]

Double check on the J valve size on the Sportsways valve. Many were 1/2" O ring. The one on the USD Al is a 3/4" O ring.

Sand Lake? I grew up in Blissfield. Dove a lot in Allen Lake and Silver Lake over in the Ann Arbor area.
That was a life time ago.

I'll check as soon as I see the tank.

Does o-ring size make much difference?

My plan is to use the USD J-valve on the LP72 (which currently has the Sportsways valve).

All the lakes are still froze over here, glad you got out while you could

[luis]

He was really referring to the thread sizes.

Steel 72 were available in three different size threads.

1) The most common and most user friendly (for inspection and service) is the 3/4” NPST threads which is what most modern tanks in the US use for the neck threads. It is a straight pipe thread with an O-ring seal and the actual thread opening is a bit over one inch in diameter.

2) The next common thread that was used in the older steel 72 was the 1/2” tapered pipe thread. That one can normally be identified because some of the threads are visible. It does not use an O-ring for sealing. It is metal to metal with either Teflon tape (some used to use pipe dope in the past).

3) The third type and least common is the 1/2” straight pipe thread with O-ring seal that was introduced by Sportways. White Stag also sold some valves with this thread type, but those are really rare. The Sportways straight 1/2" valves are tanks are around, but are not very common. They are unusual enough that some hydro station don’t even own an adapter to hydro test them, but the can get if needed.

If you are familiar with the tank neck diameter of a 3/4” standard valve, you should be able to notice that the neck on the older Sportways is narrower.

Sportways also made valves with 3/4” threads in the later years (and sold the more common steel 72 type cylinder).


Note: Simonbeans was just trying to save on words, as opposed to me, who writes these lengthy explanations.

[Herman]

Note: Simonbeans was just trying to save on words, as opposed to me, who writes these lengthy explanations.

And if you think his thread explanations are lengthy, you should hear his phone ones.