what's a quick way to verify UVC from germicidal lamp?

Well, just as a follow up, while I did expose the light sealed room to the 200 W lamp for 30 minutes, I also followed up with 70% iso alcohol solution. The smell of the room did change after the lamp had been used with the characteristic strong smell of ozone.

Until the alcohol dried, I kept any animals away and also aired out the room to negate the ozone. I have now been occupying the room nearly 16 hours per day since "decontamination" and have not gotten sick like the former occupants. Still taking care to wash hands frequently above all else.

Just to share, my first experience in the realization of UVC light was when I was in shop class way back when. When we were finished with our projects, the teacher would have us place all of out goggles into a cabinet, then the cabinet was closed and the light was activated to 15 minutes. I doubt that bulb had ever been changed, plus the light was at the top corner of the cabinet. Not all the goggles would have had exposure on every side. Makes me wonder about the effectiveness.

Well, if the disinfection relied on ozone then it may have worked very well. Ozone is a better disinfectant for turbid water than chlorine because it will penetrate into the dirt particles better. Ozone in the air also works very well. Eric

Ok, I just want to say one word to you, just one word, Copper!

OK, OK same problem, getting it over the entire room. But it would be interesting to see what harmful effects having lots of copper fittings all over a hospital would cause. Most of us have spent years drinking water that spent the night in a copper pipe, so maybe no problem. Mikek

My mom had a dryer with UV lamp, think it was for the ozone fresh smell. I noticed in the hospital they had random UV lights facing up in hallways. I would think some device using filter to determine band exists. I recall hearing of a UV device wheeled into rooms for sterilization.

Greg

Wonder what is this all about...

UVC germicidal lamp uses Hg vapor discharge. This produces UVC because of the pure physics of that discharge so if you see the lamp lights up you can be 100% sure it produces UVC. It simply can't do otherwise unless that Hg transmutated into another element but one would need a philosophers' stone for that to happen.

Intensity is another question but that can be judged from the current that lamp draws.

illing

nks.

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 illuminated. Both 175 and 400 watt bulbs were tested. Can't speak much

for UVC detection without instrumentation, but a quick test might be illuminating small insects, like crickets or flies. If they die quickly, there's 99% certainty that you have UVC.

illing

nks.

Something I've always wondered about were Tesla coils. When I was a kid, I built one and let it run arcing from HV to ground for nearly an hour. When my parents arrived home from work, the house was so full of ozone that we all had to leave for a couple of hours with the windows wide opened to air out the house. Would that much ozone have killed surface bacteria as a germicidal lamp would have?

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.

It takes a LOT. Once that level is reached, however, the killing does not take a huge amount of time. And ozone concentrations will vary by the amount diffused and the amount generated as it is very short-lived.

Peter Wieck Melrose Park, PA

Amusingly the ones I purchased didn't have thos waarning.

I think... they were 185 watt replacements I picked up at Home Depot. (No one else had them).

New fixtures/ballasts have been a no no for a decade or so by now, and replacement lamps have been attriting down.

About ten years ago I found a drop-in flourescent replacement for the aforementioned 185 watter. The power factors/wave forms/ how it worked... made my head hurt, but somehow it did.

(We've since swapped the whole fixture for an LED unit).

Oh, here we go:

"1975: Securilux (Safe-T-Vapor)

"This was the first mercury lamp with a safety mechanism that extinguished the arc tube in case of an exterior light bulb smash. "

Some mercury lamps have quartz envelopes, that take the high temperature, but those ALSO pass UV. Most low-intensity lamps don't need quartz. and glass that is opaque to UV is easily formulated. Welder's helmets always have such a glass filter (in addition to the visible-light-attenuating dark ones).

Heck, some halogen incandescents need a safety glass pane, as well.