Steel 72's into doubles?

[Ob1Stogie]

I have a set of older steel 72's that just got back from hydro and I'm thinking of using them as a lightweight doubles set up. How difficult is going to be to find a manifold for old 72's (I think both of them are from the late 60's) and bands?

I currently use them for my wife, since they are negative and thinner than AL80's.



EDIT: Never mind, I found lot's of old threads with all the info I need. Thanks.

 

[DennisW]

Walter used Steel 72s for his doubles. I know he has had this setup for years. I don't know how hard it is to get a manifold for them today.

 

[artek]

I am not sure, don’t quote me on this, I use sea elite manifold and highland bands on my 7” dia. tanks
Are yours 6.9”dia?
I think this set up should work well.
Verified first, though.

 

[Sideband]

I have a set of doubled ST72's but I bought them that way so I don't know about parts availability. I do know that they are different to dive. I have to wear ankle weights with them or I end up standing on my head. No way around it. There isn't enough height to the tanks to adjust for trim. I have not dove them enough to know just how much I like or dislike them but I do know that without the ankle weights I would not even consider getting in the water with them again.

Joe

 

[DA Aquamaster]

I like using steel 72's for doubles.

I admit that the bands often need to be set as high on the body of the tank as possible (just where it begins to round into the shoulder). And that it hels if the tanks are seated as low as possible relative to the wing on the back plate as possible. So being able to trim them properly is often a function of having both a wing and backplate with holes in them allowing vertical adjustment.

If that's the case you are good to go with the only possible downside being that you may need a little extra flexibility to reach the lower than average posts on the manifold.

I rediscovered this last weekend when I froze up my backup second stage filling 200 lb lift bags in 40 degree water and discovered I had lost some flexibility during the winter diving hiatus. So worst case, you may have to loosen the waist strap and hike things up a few inches to reach the post until you improve your flexibility.

 

[Peter Guy]

Question -- are the lp 72's (late 60's vintage), negative empty or positive?

 

[Ob1Stogie]

I just went out and put one of them in my pool and it floated (yes, it's near empty). Which makes me re-think these as doubles, cause I hate floaters. BTW, one has "born" date of 1964, the other 1966. It's amazing how long these last.



BTW, I think it may just be the plastic boot that makes it float, since it sits valve down in the water.

 

[captndale]

Question -- are the lp 72's (late 60's vintage), negative empty or positive?

They are negative. They make a sweet rig as doubles. Low profile, comfortable and light weight when out of the water. I have seven sets of them.

 

[DA Aquamaster]

They vary a bit based on manufacturer and vintage but a generic steel 72 is generally neutral to 1.0 lb negative when empty.

As I said before I like them and I own a bunch of them. They can be interesting to mate into a set of doubles as the heights can vary slightly so worst case you may need to put a small shim in the bottom of a tank boot to even them up.

Capacity wise steel 72's hold 71.2 cu ft at 2475 psi and 64.7 cu ft at 2250 psi., so you won't actually get 72 cu ft out of them, which is important to know for gas planning purposes.

 

[Ob1Stogie]

Duh, I just realized that one of them has a 1/2 inch neck and the other a 3/4 neck. Guess that kills my doubles plans!