Vintage Double Hose

I just bought two USD tanks, 6.9 diameter, 1800 psi, about 23.5" tall. I believe they are about 50 cu ft in volume. Can anyone verify or correct me?

Thanks,
Steve

I have a set of 38s that are 1800 psi and my 50s are 2250psi. Do they have real round bottoms?

No, not real rounded. Bottom shape seems to be the same as my USD 2250psi 72s - a short, quick taper to an almost flat bottom.

I found a post, a few pages back that led me to believe they may be about 50 cu.ft. The serial number begins with a K, if that means anything.

Thanks for your response.

-Steve

Well ive got nothing else useful. I guess I can look through the catalogs. Are they painted?

Steve-
It sounds like you have a set of USD 52.8 cu ft tanks. I have a twin set of the same and they are 52.8 at 1800psi +10% (1980psi)each. At 1800 psi they are only 48 cu ft. Mine have original dates from 1971 & 72 & are the same dimensions as yours. A friend of mine told me that they are approx. 2.5 lbs heavy when full in sea water, and approx. 4.5 lbs. buoyant when down to about 260 psi. I have had mine for a while but have yet to dive them. If you search a USD catalog from around 1969 or so you will see them described.

That sounds right. Looks like they show up as early as the '64 catalog and up until 70 they had that interior lining

Thank you both for your replies.
I'll be putting them together as a doubles set, but not real happy with the buoyancy characteristics. That will be a lot of positive buoyancy with two tanks.

- Steve

The reason they have positive buoyancy is that they are thinner walled tanks compared to 72's. I plan on putting a 5 lb weight attached between my set to counteract the buoyancy at the end of the dive. Steve BTW they weigh about 56 lbs (twins)when full of air. Much lighter than a set of 72's.

Jerry

Sounds good. The weight savings will be much appreciated - I'm not getting any younger.

Good advice about adding 5lbs. I'll do the same.

Thanks Jerry