Need info for an old LP 72 tank

[TSwain]

Why do you want to stay away from the ones that have the epoxy liner? Do you have to remove this liner to use them? I am just asking because I was just given 2, but they havent been used since 1985, but were still topped off with air. It looks like they have some kind of coating in side. It is brown in color, but it is not rust. The orginal hydro was 1966 & 1967. With only 2 other hydros in 1980 & 1985. Also at the rated 2250psi these are only about 64cu/cf with out the + rating, correct? And I can ask to have them tested for the + when I drop them off for the new hydro? Because the 1980 & 85 hydros dont have the + after them.
Thanks!

 

[halocline]

Why do you want to stay away from the ones that have the epoxy liner? Do you have to remove this liner to use them? I am just asking because I was just given 2, but they havent been used since 1985, but were still topped off with air. It looks like they have some kind of coating in side. It is brown in color, but it is not rust. The orginal hydro was 1966 & 1967. With only 2 other hydros in 1980 & 1985. Also at the rated 2250psi these are only about 64cu/cf with out the + rating, correct? And I can ask to have them tested for the + when I drop them off for the new hydro? Because the 1980 & 85 hydros dont have the + after them.
Thanks!

Sure, you can ask. Good luck....if you search for an old thread of mine about "hydro graffiti" you can read about my adventure asking for the plus rating from a particularly ignorant-but-exhuberant hydro tester. If they are PSTs, there is a document floating around with the PST REE numbers. That might work for getting the plus rating. It's only an extra 225 PSI, but I totally get the principle aspect to it.

As far as the epoxy linings go, there are some VIP inspectors that will reject them if there is ANY sign of compromise in the lining, as they can hide corrosion. And, some of them are supposedly pretty near impossible to get out with tumbling.

 

[scubapeter]

I've accumulated a bunch of steel 72's over the years by just keeping an eye out. I have always avoided the 1/2 inch valves as they are not the current industry standard. The last one I picked up was a 1959 us divers galvanized tank for $20 (early 3/4"). I was a bit concerned about it when I purchased it as the only other hydro date was in 1964. It was stored with about 100 psi of air in it. When I took the valve out, it have a thin coat of oil inside the tank. Following a steam clean and a hydro test from my favorite local fire equip. company, it passed with a deviance of less than 1%. The inside showed NO signs of rust or even flash. GREAT TANKS!!!

 

[Gilldiver]

I've accumulated a bunch of steel 72's over the years by just keeping an eye out. I have always avoided the 1/2 inch valves as they are not the current industry standard. The last one I picked up was a 1959 us divers galvanized tank for $20 (early 3/4"). I was a bit concerned about it when I purchased it as the only other hydro date was in 1964. It was stored with about 100 psi of air in it. When I took the valve out, it have a thin coat of oil inside the tank. Following a steam clean and a hydro test from my favorite local fire equip. company, it passed with a deviance of less than 1%. The inside showed NO signs of rust or even flash. GREAT TANKS!!!

A 1959 tank with a 3/4" valve? I had thought that the 3/4" valve was only offered in 1960.

The light oil was from the old compressors where you had to hand pack the filters, and the filters were small. If the shop was cheap, they bought the carcoal by the bag from anyone they could and cut their wifes tampax pads to act as the filter/seperator layers.

 

[scubapeter]

I think that the oil was a blessing, it preserved the steel over the years....And yes, I was surprised too at the 1959 tank w/ 3/4 inch threads. My father has faithfully followed us divers since their inception. I asked him about the tank and he said that in 1959, US Divers had numerous 3/4 inch samples that went out for testing, but the actual change over took place in their 1960 catalog. I believe other companies (voit) offered 1/2 inch tanks for a couple years after that.

 

[captain]

I have a 1958 US Divers tank that is 1/2" but has the larger neck of the 3/4" tanks so the move to 3/4" must have started in 58 as far as tank construction.

 

[sambolino44]

I think you have all the information you need already. What else do you feel you need to know.
72's were made by several manufacturers and all are relatively the same size and have the same buoyancy characteristics.

I've searched and searched and have not been able to find the "empty buoyancy" of old steel LP72s. To me, this is the essential piece of information I need to know when setting up for a dive; in other words, how much do I have to adjust my weight to use this tank?

I have several tables with buoyancy characteristics of lots of cylinders, but none of them have the old standard LP72.

So, what is the buoyancy of an LP72 with 300-500 PSI in salt water?

 

[vintagediver]

PST Galvenized @500 psi in fresh water about -1.2 (measured) with a Thermo din valve and a boot.

 

[captain]

I've searched and searched and have not been able to find the "empty buoyancy" of old steel LP72s. To me, this is the essential piece of information I need to know when setting up for a dive; in other words, how much do I have to adjust my weight to use this tank?

I have several tables with buoyancy characteristics of lots of cylinders, but none of them have the old standard LP72.

So, what is the buoyancy of an LP72 with 300-500 PSI in salt water?

Generally between -1 and +1 depending on manufactuer