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Welding suppliers now charge haz mat fees on nearly everything,
including oxygen. (I wonder if hospitals get charged hazmat on oxy?)

I bet they do. An oxygen-fed fire is pretty fierce.
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Not only a chemical/fire hazzard. A full tank [any compressed
gas even argon/helium] that is knocked over so that
valve/regulator breaks off becomes an unguided missle. Will go
through cinder block and drywall/stud walls with no problem. I
can see the headlines now after one of these go through a day
school.

Uncle George