Jump to content
UltravioletPhotography

[SAFETY WARNING] UV 10w Germicidal Sterilizer Lamp LED UVC


colinbm

Recommended Posts

SAFETY WARNING: 

UV-C is dangerous to your eyes and your skin.

UVP DOES NOT SUPPORT USING UV-C ILLUMINATION.

[UV SAFETY] UV-C Light Dangers


 

 

 

I purchased a UV 10w Germicidal Sterilizer Lamp LED UVC, to test.

 

The lamp that they sent had no marking or brands as shown in the ad.

With the extra precautions of covering myself up & protecting my eyes, I went ahead & tested the lamp.

 

When I turned it on the room had a nice ice blue glow, not unlike a 6000k cool white LED light.

 

Placing my 250-850nm spectrometer in the light confirmed the spectrum of a cool white LED, but NO spectrum below 400nm down to 250nm.

So what is going on, this is supposed the be a UVC lamp ?

 

Strangely, to me the lamp wasn't 6000k BUT 1750000k instead. So wow what is going on ?

 

Feeling ripped off, I went to my UVC fluoro lamp & placed the spectrometer in the light & there was the familiar 254nm spike, & low & behold I read 1750000k colour temperature.

I smelt no ozone either.

 

So what could this lamp be producing ?

 

post-31-0-99709700-1613963377.jpg

 

post-31-0-89088600-1613963416.jpg

Link to comment

1) You could try the banana test?

2) Ozone production starts significantly below 250nm, I think? So possibly it is not making much ozone. Or you just didn't notice it for some reason like good ventilation.

3) Sure sounds though like you got a fake UVC bulb that is just a white LED with the same color temperature as your real UVC bulb.

Link to comment

I currently don't trust any UVC LED. If it says that its using leds, I will immediately assume it to be fake until proven otherwise. They are still just far too expensive.

If you want UVC, it has to be Mercury or Krypton bulb.

 

A LED at 265nm needs to be made from aluminum crystals with a sapphire lens. Currently even at large scale still too expensive.

Link to comment

If you physically hit the germs with the lamp, then it will be "germicidal" I suppose. But it sounds like that's the only way to make the ad copy correct.

 

The only good thing about stuff like this is that fewer people will be giving themselves cancer with the real thing.

 

This is an excellent illustration of the fact that the "color temperature" of a lamp does NOT tell you its spectrum. It is only a measure of similarity to a blackbody.

Link to comment

Yes Ulf, The lamp has a clear plastic cover, but it has cuts / openings from top to bottom.

I broke off a piece of the clear plastic & it cuts the UV below the 365nm line in UVC Fluoro lamp.

 

Yes Andy, it dongs the bugs well, but some fit between the gaps in the clear plastic cover....

Link to comment

Lets also think about output. A 15W Mercury 254nm germacidal bulb might be 30% effective. There is heat loss and losses at the ballast. So the output is really is about 4.5W best maybe.

 

Now real 265nm LEDs are about 20 to 60 mW at best output. I have a feeling that the cheaper ones are driven hard with more heat loss (to burn that green banana) and may result in more doublet 530nm light production.

 

So I think you have mostly an expensive inefficient 530nm light source mainly.

 

But if working with real 265nm leds you will need at least 225 of them to equal the output of a now $20 15W Mercury 254nm bulb. So really not worth it. A year ago a 25W bulb was $15, but then COVID made these more expensive.

 

Your Led bulb looks to have about 60 leds.

Now if real, then it will be about 1W, so expect a quarter of the output of a 15W germacidal bulb at best.

Link to comment

You would need between about 450 and 560 of my 265 nm LEDs to have 4.5 W of UVC. At 1 W input power each, that would equal 450-560 W of input power, and that's a lot to dissipate (it becomes almost all heat).

 

David, why do you think these LEDs produce 530 nm (double 265 nm)? They don't work like lasers (you can double 532 nm lasers to have 266 nm), the visible light they emit is due to self-induced fluorescence as far as I know. It isn't necessarily at 530 nm, it actually looks bluish usually.

 

A spectrometer might see 530 nm because of how gratings work (second-order diffraction), and that is probably what the guy in the video in this topic saw.

Link to comment

Yes my background is microscopy and spectroscopy, so I jump to thinking second order harmonic even when it may not apply.

I am still getting my head around the gap junctions used to generate light within an LED.

Link to comment

I am still getting my head around the gap junctions used to generate light within an LED.

I am still impressed we can make semiconductors with bandgaps of 4-5 eV. It is a lot.
Link to comment

About the crazy high color temperature Colin measured, it is odd since past a certain point (like 100,000 K) the hue doesn't really change much. As the temperature grows, the color tends to a specific shade of bluish-white, and at infinity the color is still that bluish-white. It "converges".

 

Here you can see it: https://en.m.wikipedia.org/wiki/File:PlanckianLocus.png

 

Notice how the curve tends to a specific point at infinity. In the real world, an object heated at that temperature would get extremely bright, to the point where it would set fire to nearby objects, and the color would tend to that precise hue.

Link to comment

1) You could try the banana test?

2) Ozone production starts significantly below 250nm, I think? So possibly it is not making much ozone. Or you just didn't notice it for some reason like good ventilation.

3) Sure sounds though like you got a fake UVC bulb that is just a white LED with the same color temperature as your real UVC bulb.

 

It failed the green Banana test, with no marks.

Link to comment

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now
×
×
  • Create New...