On 1/23/20 3:27 PM, danny burstein wrote:
[snip]

Once upon a time, I was part of a test study on mercury vapor lamps with =

the outer envelopes broken so only the inner, strong UVC element=20
illuminated.

*whew*, thanks.

I was 99 percent sure I remembered those days of mercury arc
lamps needing that extra, outer, envelope 'cuz worries
about the UV intensity, and even that Duro Test had marketed
a "safety lamp" ("bulb") that, if the outer glass broke, would
shut itself down.

(this would have been the 1970's)

But none of the yung'uns around me believe that was ever teh case.

Any idea how they cleared up that problem? I replaced a bunch
of legacy mercury lamps about two decades ago and there weren't
any warnings on the packages.

Thanks.


Odd. I still have an outdoor mercury lamp on my property, a 250 W
lamp. I just replaced it last year and the UV warnings were still
present concerning breaking the outer envelope. So they would
definitely still emit UVC if the envelope was broken.

Ways of getting around the UVC hazard included shutdown mechanisms so
that the lamp extinguished when the envelope was broken, providing a
lamp housing that has a glass cover (like street lights have), or
switching out to something different altogether where the UVC hazard
doesn't exist such as LED. There's been an ongoing effort to outlaw the
mv lamps.