Am I the only one who sees the "three triangle with dot in the center "
    radiation hazard symbol on it? Is that normally on CO2 canisters?

It's not the right colors for a real radiation hazard warning, and it should
have a surrounding triangle rather than a circle.
        http://www.harvardapparatus.com/pdffiles/b2k_n039.pdf
A major source of "smallish" pressure tanks for amateur rocketry is
the paintball industry, and I have few doubts that they would consider
it "amusing" to have tanks with all sorts of bogus symbols on them...

(Amusing society, isn't it, where amateur rocketry is widely held to be much
too difficult and dangerous to participate in, yet a sport that involves
shooting at each other with rather painful and messy projectiles is big
enough to be an "industry."  Sigh.)

BillW

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