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Re: [APD] Re:Re: Co2 Tank

The best way to know that a tank is safe is to read the
stamped writing on the tank that specifies the DOT
regulation under which it was tested , the date of the test
(tests are good for 5 years in the US), the name or
trademark of the maker or distributor (who must be
registered with the DOT) ), and of course, no visible
damage or signs of mistreatment.

The markings can appear cryptic at first. But once you know
what they're supposed to show, it's easy. One place to find
out is skin diver web sites like this:


which has more info than you ever wanted to know.

Shorter version is this:

DOTxxxx  where the xs are numbers = DOT spec udner which
the tank was made, usually 3AA2015, which means a seamless
steel tank for up to 2,015 psi working pressure or 3AL1800,
which means the same thing except aluminum tank for up to
1800 psi working pressure. the "3AA" means steel and "3AL"
means aluminum. You get the idea.

Test pressure if indicated by the prefix "TP" will be 3/2
times the operating pressure for which the tank is safe.

TWxxx lb.s  = Tare Weight of tank The Tare weight is
usually followed by the net weight of compressed gas.

One or two digits followed immediately by a trademark
symbol of any kind followed by two digits = digit(s) before
the symbol = month of first test and the digits after = the
year of first test.  The symbol is just a brand trademark.
The test date is easy to find because the trademark symbol
sits between the month and year.

Regarding the valve on the tank, the Compressed Gas
Association (CGA) has established standards for tank valves
for various compressed gases. CGA 320 specifies the
standard for CO2 valves. Other gases have other numbers
that specify different valves -- CGA 580 means argon. The
point is to prevent mixing gases by having diff valve
fittings for diff gases.

Unfortunately other countries have other markings.

If you find someone selling tanks as purportedly for CO2
and they are not stamped, give the vendor's name to the
DOT, the vendor has some prison time coming their way ;-) 

Buying a tank on-line or local (swap or not) can be cheaper
or more expensive. Shopping around is the only way to know
if local options are financially favorable. Make some
calls, look up some web stores -- shop around.

Scott H.
--- Robert H <robertph3 at comcast_net> wrote:

> . . .Buy one filled
> with gas local, save shipping charges, and be confident
> it has been
> certified for safety.

Still some time to get the $59 registration rate -- it must increase as of October 28th to $79.

Still some time left to get the 65% discount hotel rate.

The Annual AGA Convention, 2004, November 12-14.
aquatic-gardeners.org & gwapa.org
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