Re: Steel tank help

Tazz wrote:
Art Greenberg wrote:
On Fri, 31 Aug 2007 00:34:58 -0300, Tazz wrote:
El Stroko Guapo wrote:
Tazz wrote:

A friend of mine has an old steel tank that he wants to use to fill his paintball guns. It passed the hydro and visual, but we can't positively determine what pressure to fill it to. My best guess is 2250 psi. but I don't know for sure. It doesn't match any of the spec charts that I can find on the net.

Here's a pic: http://www3.ns.sympatico.ca/dmswaine/images/steel tank.jpg

My best guess would be that 7MH81+ means the first hydro was done in 1981 and it could be overfilled 10%. The 2250 I guess is the max pressure. Am I right or way off? Also, it has some kind of dive/reserve lever on the valve. Would somebody like to explain how that worked?



Your link doesn't work (even with massaging), but I'm guessing it is a garden variety steel 72 which holds 65.1 cf at 2250. The + indicates it can be overfilled until '86. Unless yer current hydro is a +, many fill shops will not overfill it.

The valve is J valve, which we used before the fear-mongering marketing pukes sucked us all into using SPGs. When an increase in breathing resistance is felt, you use the rod to trip the reserve lever and time the remainder of yer dive. Because they don't corrode, dangle, entangle, or explode at the most inconvenient time, they were taken off the market and replaced with "life $upport" equipment.

esg


Sorry about the link. Try this: http://www3.ns.sympatico.ca/dmswaine/images/steel%20tank.jpg

If all else fails, copy and paste.

ESG is correct. That's a low-pressure steel, max fill pressure 2250psi,
as indicated by "DOT3AA2250". There isn't any marking indicating
capacity, but it probably is a 72 cubic foot capacity (when filled to
2475psi, as permitted when the current hydro stamp includes a "+" mark).

There are two hydro stamps visible, one 8/1973 and the other 7/1981.
Both are "+".

There is a formula that gives approximate volume for a scuba cylinder on
the PSI website:

http://www.psicylinders.com/library/Current/cylinder_volume.htm

I suspect the cylinder was manufactured (by Voit?) in 1973. I say this
because the serial number starts with "73-", and the earliest visible
hydro stamp is from 1973. That stamp is in the expected place, under the
serial number. I am bothered that the "VOIT" stamp isn't well aligned.
It looks like it was done letter at a time, which seems odd for
something a manufacturer would do hundreds or thousands of times.

The original hydro facility is indicated by the stylized "CL" between
the month and year in the 8/1973 hydro stamp. I have no idea what the
meaning of the "PST" stamp following the original hydro stamp is. It,
too, appears to have been done letter at a time.

I do NOT see a current hydro stamp.

One other thing. Early 72cf cylinders were made with a tapered pipe
threads, not the non-tapered threads used today. I only vaguely recall
my PSI cylinder inspection class from many years ago,

Thanks guys for the info.
The current 07 hydro stamp is on the other side of the cylinder. The picture came out blurry so I didn't put it on the website. The last + was in '91. It has not been tested since 95. Don't know why there were only four years between tests.

>but I _think_ such cylinders are no longer legal. I'm sure someone >else will correct me if that isn't true.
>

Not legal for diving or not legal to have at all?

The 1/2" pipe thread tanks are legal, just a pain. I have and use a couple myself. Some dive shops MAY not pass them because (A)they don't know any better, (B)they are really old... see A and (C)they are a pain.

Tim

--
Captain of the Kilauea Volcano Jumpers
The Big Islands Firediving Team
http://www.firediving.com
.

Relevant Pages

  • Re: Steel tank help
    ... It passed the hydro and visual, but we can't positively determine what pressure to fill it to. ... My best guess would be that 7MH81+ means the first hydro was done in 1981 and it could be overfilled 10%. ... as permitted when the current hydro stamp includes a "+" mark). ... I suspect the cylinder was manufactured in 1973. ...
    (rec.scuba)
  • Re: Steel tank help
    ... It passed the hydro and visual, ... as permitted when the current hydro stamp includes a "+" mark). ... the PSI website: ... I suspect the cylinder was manufactured in 1973. ...
    (rec.scuba)
  • Re: Steel tank help
    ... It passed the hydro and visual, but we can't positively determine what pressure to fill it to. ... My best guess would be that 7MH81+ means the first hydro was done in 1981 and it could be overfilled 10%. ... Unless yer current hydro is a +, many fill shops will not overfill it. ... The valve is J valve, which we used before the fear-mongering marketing pukes sucked us all into using SPGs. ...
    (rec.scuba)
  • Re: Steel tank help
    ... It passed the hydro and visual, but we can't positively determine what pressure to fill it to. ... My best guess would be that 7MH81+ means the first hydro was done in 1981 and it could be overfilled 10%. ... Unless yer current hydro is a +, many fill shops will not overfill it. ... The valve is J valve, which we used before the fear-mongering marketing pukes sucked us all into using SPGs. ...
    (rec.scuba)
  • Re: Steel tank help
    ... It passed the hydro and visual, ... determine what pressure to fill it to. ... VOIT = Scuba-equipment manufacturer (they didn't make the tank; ... contracted compressed-gas cylinder companies to supply them with their ...
    (rec.scuba)