Vintage Us Divers Tank Id (with Pictures)

[WebmasterJ]

Recently got a vintage US Divers tank and was happy to find out it still had air it it and after opening it up and seeing the inside looked great I sent it off to HYDRO and it passed with no issues.

Have done a bit of searching and am not sure how many cf this tank holds when filled to the rated 1800 PSI.

The tank is 24" tall and has a round bottom, 22" circumference and a diameter (calculated from 22" circumference) of 7"

Markings on Tanks:

US DIVERS

DOT3AA 1800
K153024 (some of those are tough to read so not certain, pic attached)
USD
S070

Would like to know if anyone is familiar with this tank and would like to know the size/cf of the tank.

Thanks!

 

[2airishuman]

Looks like an LP53. I have one. 52.8 cf at 1980 PSI.

The empty weight of the tank would determine it for sure. 22 pounds empty?

 

[WebmasterJ]

21lbs 11 ounces with the tank empty without valve (with boot)

23lbs 1 ounce, with tank empty, valve, and boot

 

[Luis H]

If you really want to determine the exact volume, just fill it with water and measure the weight of the tank, boot and water.

You have to make sure to dry it as soon as you empty the water. I use compressed air from another tank with a hp hose attached to a 1/4 inch copper tube long enough to reach the bottom of the cylinder. This methods blasts all the water out before there is any chance of any flash rusting.

Note: I have been doing this for decades and I have never had a tank with flash rust.


I have measured the actual internal volume of all my cylinders and it is interesting the variation in volume, from the actual published volume. My steel 72 actually range from about 69 to 72 cu ft. The average (from 16 cylinders) is about 70.6 cu ft.

 

[WebmasterJ]

Luis, I thought about doing a volume test with water but after my last set of tanks came home with flash rust (the HYDRO shop did not dry or use a rust inhibitor) I am a little paranoid.

I don't need to know the exact volume but would like to know a little closer than "38-70"

 

[2airishuman]

That's an LP53. (or LP52, take your pick)

I measured mine when I got it, and according to my notes:
internal volume in liters 11.0
weight in pounds without valve or boot 22.0
calculated capacity 52.8cf
diameter inches 6.9
height without valve or boot 23.7

I haven't measured buoyancy but they're supposed to be about +3 pounds empty.

They aren't especially useful unless you are in a situation where you need a lightweight tank that will fit into a BC in the usual way, or want a very low pressure tank because you're transfilling. Back in the 1970s they were sold as a lighter weight alternative to LP72s for divers of small stature who didn't need much air and who found the weight of a 72 to be awkward. The thing is though that because they're floaty you need 3# more lead than an LP72, and an LP72 weighs 28 pounds, so there isn't much weight savings.

I keep mine around and use it for non-diving purposes, like testing regulators and filling tires.

 

[WebmasterJ]

Thanks 2airishuman.
Using the tank as a hang bottle, an area I dive they don't have a booster to 2k PSI is all I am going to get and 52 CF will be plenty. I may have to play with buoyancy after putting regs/hardware on it.
Appreciate the info.

 

[John C. Ratliff]

I have a set of these tanks that I have set up as doubles. They replace my twin AL 50s, which I have decommissioned due to SLC issues with the AL tanks. I tie two 3 pound bullet weights on them in the center, and that handles the buoyancy issues.


Note that I don't dive the Aquamatic in open water.


Here they are with my Broxton DA Aqualung.

I also have used this tand with my Dacor Nautilus CVS, which has its own weight system so that their buoyancy isn't an issue (for my shallow, river dives).



Here is the USD catalog information on these tanks.



SeaRat

 

[CKH]

So I just picked up a pair of similar tanks and was told the problem is getting burst disks. I want to upgrade the manifold since i'm not too interested in going full vintage. Has anyone here had issues sourcing proper burst disks for these 1800psi tanks?