Here is the HAZMAT
advisory (issued sometime ago) and the DOT regs. These are the rules
that should be quoted, especially the latter.
HAZMAT Advisory... DOT Advisory AL 6351-T6 Cylinders.pdf
DOT regs... DOT Scuba Cylinder Requalification Regs.pdf
The source of this info was from the following Email received by Ian...
-------------- Original message from Allen Sanderson <firstname.lastname@example.org
>Just stumbled across your newsletter in a web search. The article
> on the older scuba cylinders needs to be corrected.
> Aluminum cylinders that are made from the 6351 are safe to use -
> however they require an additional level of care that the newer
> cylinders do not require. This additional level of care are the
> current tests. DOT issued new rules on this that are effective 01
> 07. That article should have noted this and NOT said they were
> to use.
> It did correctly note many shops are now refusing to fill
> made from 6351. That it their option but it shows that when it
> to the scuba industry and its ability to self regulate cylinders
> Allen Sanderson
> Salt Lake City