filling 72's

[IowaCaveDiver]

I didn't realize there were concerns with filling LP72's to the standard NFL cave fill- 3600psi... that being said, do you know which shops will or won't fill past the indicated working pressure? Also what are some of the most recent documentations of LP72's exploding if this seems to be the concern. I tried to have them filled today without luck and the concern seems to be thinner sidewalls with this age of tank. I wasn't aware of these issues till now... can anyone fill me in? I didn't find any threads on this forum after searching...

-Matt

[Rich]

Hey Matt!

Are you talking about the old school 2250+ steels?

Safe diving,

Rich

[IowaCaveDiver]

both actually... I have a couple of each

[Meister481]

Some 72 sized tanks have a fill pressure of 1800 psi. Be careful! I don't fill mine over 2900, ever.

[Diverlee]

I have old ones, from the 1970"s. I only fill to 2400psi. I just don't feel comfortable over filling something that old. If I need more gas I just use a larger tanks.

[Sludge]

Weak necks. 2400psi max.

[WEPIV]

I have an old 72 from my uncle that dates to the late 1960's. He had it filled for years down in the West Palm area but after Frank's dive shop closed he could no longer find a place to fill it.
He gave it to me and I brought it up to my home in the north Florida area where we had it fully inspected -- hydro and VIP -- and it passed with no problems and I've been filling it ever since with no issues.
I try to keep it at or under 2500 psi.

[IowaCaveDiver]

All great points... just dissapointing, I should have done my homework... I really had no idea there were issues with these older tanks. But thinking about it, we got them for doing shallower caves (50' deep or less) and compared to diving a set of 80's, when pumped to 3000 you've got a 33% overfill and 96 cu ft of gas... I was doing 2 hour long dives in mexico at similar depths, so I think these will work great for some of the river caves we like to visit... especially that they are easier for my girlfriend to lug and she doesn't breathe half the time anyway, so it is probably overkill for her

[akcaver]

Matt,
The bouyancy chars of steel 72s are also much much better for sidemounting than AL 80's, and that has been the primary reason i use them for short [or shallow or small] cave and river cave dives. I also fill my own, and dont bring them past 2600 warm, about 2400 cold. And, if you think of it, the gas volume difference is really small between 80's and 72s. If both are full (80 and 72 cubic feet) and you are diving thirds (one third = 26.7 and 24 cubic feet), the gas diff is less than 3 cubic feet, and if youre SAC is between 0.5 and 1, thats only a few minutes extra of gas, which is usually less than 200 ft swimming distance.

Sorry for the long exp... but dont fill them past 2400 cold!

[skip]

All great points... just dissapointing, I should have done my homework... I really had no idea there were issues with these older tanks. But thinking about it, we got them for doing shallower caves (50' deep or less) and compared to diving a set of 80's, when pumped to 3000 you've got a 33% overfill and 96 cu ft of gas... I was doing 2 hour long dives in mexico at similar depths, so I think these will work great for some of the river caves we like to visit... especially that they are easier for my girlfriend to lug and she doesn't breathe half the time anyway, so it is probably overkill for her

I use mine as sidemount in shallow caves (<50ft, ave 20) and for initial investigation. and sometimes just because they make it so easy.

I dove them backmount for awhile and that too was like wings on your back, not tanks.


Originally Posted by IowaCaveDiver
? Also what are some of the most recent documentations of LP72's exploding if this seems to be the concern.

-Matt

I too would like to know; is there a list of tanks that have exploded that also shows size, original hydro, material, volume, etc.? who keeps the records? DOT?

-skip