Cave Fills and Burst Disc Rating?

[tbone1004]

I fill mine to 3200-3300 and let them cool off to 3100 or so

 

[Jack Hammer]

So what pressure would you cave fill those old steel 72s with 2250+psi rating? I got one from 1977 and inside is very clean and it would be nice to have 80 cf or gas in it. Can you go 2800psi and treat it as a 80 cubic foot tank? if yes can you let it sit for a week or more at those pressures? it is only 25% over fill so should be fine no? Is 3000psi crazy for these 40 year old tanks?

I fill to 2800-2900psi on my steel 72s from the mid 60s.

 

[2airishuman]

So what pressure would you cave fill those old steel 72s with 2250+psi rating? I got one from 1977 and inside is very clean and it would be nice to have 80 cf or gas in it. Can you go 2800psi and treat it as a 80 cubic foot tank? if yes can you let it sit for a week or more at those pressures? it is only 25% over fill so should be fine no? Is 3000psi crazy for these 40 year old tanks?

I would ask you what your goals are.

I have about six LP72s. I like them. They are all + rated. I fill them to 2475 or maybe 2500 and get a nice dive out of them. If I want a longer dive, I use an HP120. I have about six of those, too. Or you can get an HP100.

LP72s have never been extensively used for cave diving and therefore have no extensive track record of withstanding "cave fills" as is the case with LP85s, LP108s, etc.

AL80s are 77 cf, LP72s are 71 cf. From a standpoint of the actual dive experience the 6 cf difference is insignificant. Maybe 5 minutes more time if your dive time is limited by gas. There are people who run them to 2700 which will give you the same 77cf as an AL80. I don't.