I was given this tank

[ScubaBunga]

Your tank has the hydro plus rating. When you get a hydro make sure they do the plus test. To reach full capacity you need it. Without the plus test the operating pressure is 2250 psi. With it it's 2475 psi and that pressure is needed to give you the full capacity of the tank. At 2250 it's a short fill by 10%.

One thing is curious to me. I thought LP steel tanks were 2400 not 2250 for a plus fill of 2640. All mine are 2400 psi.

+1 on the buoyancy charistics of steel.

Not sure on new ones but the old standard 72s are all 2250 (2475 with the plus). Many hydro places won’t plus the tanks anymore as there is no easy way to find the ree needed. My hydro place won’t plus without manufacturer docs on the exact serial number ( and ths3s manufacturers don’t make tanks anymore and have no docs, I’ve checked). I may have found a place that will plus them (they have enough history to work out the ree) but until I take my tanks in I won’t know for sure. It’s most likely still a good tank unless the inside is just trashed. Someone will want it if you don’t.

 

[Pedro Burrito]

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[TrimixToo]

I make sure I do. Still not sure I’d i even get it hydro done.

If you need a tank that approximate size, it's a great choice as long as it's not a lined tank. Not a lot of them were lined, but check. A hydro and perhaps a tumble (and O2 cleaning for partial pressure blending of, say, nitrox) and you're good to go. It is extremely likely to pass the hydro. I have 10+ of these, all bought used, some made in the 1960's. None have ever failed. They are slightly shorter and smaller in diameter than AL80's, which is a plus.

 

[Bob DBF]

One thing is curious to me. I thought LP steel tanks were 2400 not 2250 for a plus fill of 2640. All mine are 2400 psi.

The HP / LP thing came along for new tanks after the Old 72's went out of favor. I usually refer to them as old steel 72's or old school 72's (or 50's or whatever...) to avoid confusion with the newer tanks.

Not to mention the Faber MP (mid pressure) tanks with either 3000# or 3180# service pressures.


Bob

 

[rjack321]

Your tank has the hydro plus rating. When you get a hydro make sure they do the plus test. To reach full capacity you need it. Without the plus test the operating pressure is 2250 psi. With it it's 2475 psi and that pressure is needed to give you the full capacity of the tank. At 2250 it's a short fill by 10%.

One thing is curious to me. I thought LP steel tanks were 2400 not 2250 for a plus fill of 2640. All mine are 2400 psi.

+1 on the buoyancy charistics of steel.

You will be hard pressed to get an lp72 plus rated as the REEs are not readily available.

 

[Kharon]

You will be hard pressed to get an lp72 plus rated as the REEs are not readily available.

Then it's not a 72 it's a 64.8.

 

[AfterDark]

I make sure I do. Still not sure I’d i even get it hydro done.

I don't have a 72 younger than 1973 oldest is 1960 anybody will hydro your tank. Not everyone can or is willing to do the 10% over testing.
It may need rolling to clean the inside of any light rust but it's a fine and useful tank.

As I have said before there are an unknown number of steel tanks on construction sites that are older then I, some made during 1940's they all get tested and are subject to the same hydro requirements as scuba tanks, if they are transported over public roads.

 

[rjack321]

Then it's not a 72 it's a 64.8.

Good grief
When you pick up an al80 from the shop and its underfilled to 2700psi do you call it a "69.3cf tank"?

 

[rhwestfall]

Good grief
When you pick up an al80 from the shop and its underfilled to 2700psi do you call it a "69.3cf tank"?

and actually, it isn't an AL80, but a AL77.4... and there is no 10% overfill provision on aluminum tanks, so it never was an "80"

 

[Kharon]

Good grief
When you pick up an al80 from the shop and its underfilled to 2700psi do you call it a "69.3cf tank"?

A short fill is a short fill. A tank that will be short filled 10% plus whatever decrease in pressure occurs from the fill itself can significantly affect the air available and thus the length of a dive.

Yep A 10% short fill on an AL-80 is a tank holding only a nominal 69 CF of air. Are you going to plan a dive expecting 80 CF? I'm not.