UVC Sanitizer Box - mostly fake

alpg88

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at the begining of covid i bought 3 8w uvc fluorescent lights, installed 2 in my bathroom. i turn them on for about 15 min, after that the whole bathroom smells like chlorine, it does make plenty of ozone, which is a good thing. We no longer disinfect clothes, but i run that thing daily anyway. it removes all smell of poop from cat's litter box. however it has no effect on urine smell. guess it is not caused by bacteria, so UV cannot kill it.
 

Dave_H

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I recently acquired a Globe brand UVC disinfectant box model 60057 obviously on surplus/clearance as the price was $10 (on sale for $5).

Inside are four square gold-coloured SMT LEDs (280nm), only on with box lid closed. I found the interlock is magnetic, easily fooled. It runs from USB (2W max.) and uses a 15-minute timer. Other than that, no technical info.

It lights up some of my day-glo posters and other fluorescent material.

I bought it not for its original purpose, but with COVID surging once again who knows (except experience suggests most transmission via "aerosol" versus solid surfaces).

Dave
 
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fulee9999

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To avoid this issue ( being sold a blue LED instead of UVC ) I actually made my own small sanitizer

1657211513649.png


You can buy these 3,5mW 275nm UVC LED modules and you can daisychain them, so the whole assembly runs off of one USB-C connector.
One module was around $10, so this is a $50 contraption, but tested with an UVC dosimeter this actually works.

Whenever you buy something that is claimed to be UVC:
1, Make sure it actually emits any UVC at all, you only need a cheap tester card for that, like so:

1657211756368.png

2, Check the dose it emits, you will need a dosimeter card for that, like this one:
( this is what some hospitals in the US tend to use )

1657211898177.png
 

alpg88

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Exposure to ozone can be a health hazard...be careful!

Dave
Yes it can be if you get exposed to high concentration for certain amount of time, but it also has many benefits.
 

alpg88

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I don't think UVC LEDs will generate ozone. IIRC the mercury vapor line that produced ozone was in the ~180nm range.
They should if they are of proper bandwidth, oxygen does not care if it is a led produces uvc or a fluorescent bulb. problem is all those fake uv sterilizer boxes do not have such leds, and even if some do their power is way to small to make any measurable amount. those leds make milliwatts.
I use fluorescent bulbs 2x 8w, i get plenty of ozone, it would be extremely expensive to make 16w with true uvc leds.
 
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PhotonWrangler

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They should if they are of proper bandwidth, oxygen does not care if it is a led produces uvc or a fluorescent bulb. problem is all those fake uv sterilizer boxes do not have such leds, and even if some do their power is way to small to make any measurable amount. those leds make milliwatts.
I use fluorescent bulbs 2x 8w, i get plenty of ozone, it would be extremely expensive to make 16w with true uvc leds.
Back in the 80s or 90s they revised the formula for the glass envelope on fluorescent germicidal lamps to cut off the shorter wavelengths and thus cut back on ozone production. I've had both types of 8w tubes and the newer ones are much less stinky. Wavelengths longer than 240nm won't react with oxygen to produce ozone. I haven't seen any UVC LEDs that produce spectra shorter than 255nm yet. That doesn't mean it won't happen someday though.
 
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Dave_H

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I've found yet another (locally) heavily-discounted Globe-brand LED "disinfection" light #26180, which combines regular white LEDs in a USB-rechargeable 14" light strip, with some UVA/UVC LEDs and motion detector.

I think I payed less than $10. Still seeing regular price US$59 and up, not worth that much in my opinion.

Besides visible SMT LEDs, inside are eight LEDs which appear to be UVA, and one gold square LED which is likely UVC (they state 352nm and 280nm respectively). UVA is barely mentioned on package.

It's designed to do a disinfect cycle but shut UV off when motion is detected. Interesting feature but not sure how well it works in reality, and no plans to use it for this. So while the claims are not exactly untrue, it seems to create confusion as to how useful it is for COVID (on most peoples' minds).

Dave
 

PhotonWrangler

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I've found yet another (locally) heavily-discounted Globe-brand LED "disinfection" light #26180, which combines regular white LEDs in a USB-rechargeable 14" light strip, with some UVA/UVC LEDs and motion detector.

I think I payed less than $10. Still seeing regular price US$59 and up, not worth that much in my opinion.

Besides visible SMT LEDs, inside are eight LEDs which appear to be UVA, and one gold square LED which is likely UVC (they state 352nm and 280nm respectively). UVA is barely mentioned on package.

It's designed to do a disinfect cycle but shut UV off when motion is detected. Interesting feature but not sure how well it works in reality, and no plans to use it for this. So while the claims are not exactly untrue, it seems to create confusion as to how useful it is for COVID (on most peoples' minds).

Dave
Interesting. This sounds similar to a "Honeycomb" UVC puck light that I picked up from the chain that rhymes with Bernard's. It contains one visible white LED and two gold UVC LEDs driven by a motion sensor. It's meant to mount under a cabinet or inside a medicine cabinet. When it see motion, the white LED turns on for around 30 seconds, then it turns off and the UVC LEDs turn on for 30-60 seconds or so. I thionk I paid $25 for it (regular price at the time).
 

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