| Electronics > Projects, Designs, and Technical Stuff |
| Cheapest way to check if a UVC bulb is as advertised? |
| << < (9/9) |
| pipe2null:
Thanks everyone for the great feedback! --- Quote from: LaserSteve on April 05, 2020, 07:59:03 am ---Check your PMs, Pipe2Null. I just sent you a link to overstock from a reputable optical filter manufacturer. Steve --- End quote --- Awesome, thanks! I'm checking it out. --- Quote from: Zero999 on April 05, 2020, 11:48:17 am ---Is there any reason why your application requires LEDs i.e. having many on/off cycles, free from mercury (by the way low pressure germicidal lamps contain tiny amounts of mercury), no glass to shatter etc.? If not, just use mercury lamps. They're much cheaper and more efficient, than LEDs, given the same power ratings. --- End quote --- My purpose related to UVC is 2 parts: Part #1) There are a lot of people out there desperately trying to hack together something to sterilize one thing or another. There is a pretty long thread started by a guy who was trying to effectively sterilize the face masks his (medical professional) wife has to re-use. I am not in any way an expert on these things, but I can work to find the right information and post it so those with no other choice but to hack something together might have a reasonable chance at succeeding. I've seen posts where someone says to bake it at 60 degrees C for a while, but I found a study on SARS that required a minimum temperature of 75 degrees, so... As far as the UVC LED products on Amazon go, I have been told by multiple people that it is not possible to produce a UVC LED light product with a useful LED count that can sell as low as $50 or $100. If those products are scams, not only are desperate people getting cheated out of money, but the sterilization they believe is occurring is NOT, so, if they are indeed scams then the continued sales of those products actually promotes the spread of COVID-19. I kinda think that's a bad thing... ;) Part #2) I had a crazy idea to use a powerful enough UVC source to sterilize exhaled air in psuedo-real-time from infected people who need to use CPAP/BiPAP/etc for one reason or another. This includes (possibly healthy) people who normally use CPAP on a daily basis but have stopped due to warnings related to COVID-19 being expelled as an aerosol. Theoretically at least, it might be possible to do this with zero filters, which are in short supply globally. I should have a "textbook" on UVGI for surface and air sterilization tomorrow, so that should have most of the important info needed. The problem is availability of UVC sources with minimal lead time, and which ones might be suitable. I freely admit that it is Bass Ackward to design a "UVC light in a can" aka "bio reactor" based on what UVC source "just happens" to be locally available instead of the other way around. Which brings us back to products currently listed on Amazon. And back to Part #1 since anyone attempting to use UVC for something important has the same problem I'm currently facing. As for the current thread: I would appreciate recommendations on a "technical reference/textbook" that contains the right information to measure the output of UVC/radiating sources, preferably one that contains the "cheat sheet" equations to use for typical geometries so you can calculate total output based on point samples taken at specific positions around the UVC source. Hopefully I will not end up needing it, but there is a lead time so I should order it asap. Worst case it will be a welcome addition to my library. Decades ago, I vaguely recall I got a degree in EE, but after many professional years only on the software side of things... Well, saying that I have a lot of relearning and catching up to do is a gross understatement. |
| james_s:
LEDs are pretty much a non-starter, at least right now. Currently nothing we know of comes close to a low pressure mercury discharge for generating copious amounts of UV. The lamps are essentially identical to conventional fluorescent lamps but without the fluorescent part, or at higher power densities there are high pressure mercury discharge lamps available up into the kilowatts. They are quite efficient at producing UV, one of the reasons mercury vapor lamps have been considered inefficient is that much of their output is UV which is not useful for illumination. |
| helius:
In another thread on UV-C disinfection, a poster mentioned that the base of an EPROM eraser could be removed, transforming it into a shortwave ultraviolet lamp. I have one of the same units, so I did the same. One of the things I noticed is that its ABS plastic housing fluoresces bright green under the UV-C rays. This is at least an indication that the proper wavelengths are being output from the tube. The rated power of the tube appears to be 8 W (the ballast is rated for 2, 4, or 8 W), and at 30% spectral efficiency that is about 2.5 W of UV radiation. BTW, the discussion above about "instant start" vs "programmed start" is good. This unit has "manual start"! The power switch does preheat as long as it is held down, and kicks when released. |
| Zero999:
--- Quote from: helius on April 05, 2020, 08:46:43 pm ---In another thread on UV-C disinfection, a poster mentioned that the base of an EPROM eraser could be removed, transforming it into a shortwave ultraviolet lamp. I have one of the same units, so I did the same. One of the things I noticed is that its ABS plastic housing fluoresces bright green under the UV-C rays. This is at least an indication that the indicated wavelengths are being output from the tube. The rated power of the tube appears to be 8 W (the ballast is rated for 2, 4, or 8 W), and at 30% spectral efficiency that is about 2.5 W of UV radiation. --- End quote --- If you have a known good lamp, then I agree the fluorescence of the plastic is a good indication that it works, but plastics often fluoresce at longer non-germicidal UVA wavelengths, so it's not a test to prove an unknown lamp doesn't just produce UVA and no UVC, unless you're sure it only fluorescences under UVC. --- Quote from: james_s on April 05, 2020, 05:02:21 pm ---There's no reason one couldn't be made however I've never seen one. --- End quote --- Googling for electrodeless germicidal brings up a few microwave excited mercury vapour lamp. --- Quote from: james_s on April 05, 2020, 07:24:33 pm ---LEDs are pretty much a non-starter, at least right now. Currently nothing we know of comes close to a low pressure mercury discharge for generating copious amounts of UV. The lamps are essentially identical to conventional fluorescent lamps but without the fluorescent part, or at higher power densities there are high pressure mercury discharge lamps available up into the kilowatts. They are quite efficient at producing UV, one of the reasons mercury vapor lamps have been considered inefficient is that much of their output is UV which is not useful for illumination. --- End quote --- Yes go with mercury vapour for UVC. By the way nearly all modern mercury vapour lamps used for visible lighting use phosphors to boost the efficiency and are therefore really fluorescent lamps, even though they're not known as such. This is evident from the fact they're opaque/translucent white when unpowered. See the example linked below: https://www.bltdirect.com/venture-mercury-blended-lamps-delux-mbf-mbfudl-50w-e27?adcid=pla&gclid=EAIaIQobChMInZ_Kh5PS6AIVCPlRCh1EQwIDEAQYBSABEgIr2PD_BwE --- Quote from: pipe2null on April 05, 2020, 07:11:46 pm ---Part #1) There are a lot of people out there desperately trying to hack together something to sterilize one thing or another. There is a pretty long thread started by a guy who was trying to effectively sterilize the face masks his (medical professional) wife has to re-use. I am not in any way an expert on these things, but I can work to find the right information and post it so those with no other choice but to hack something together might have a reasonable chance at succeeding. I've seen posts where someone says to bake it at 60 degrees C for a while, but I found a study on SARS that required a minimum temperature of 75 degrees, so... As far as the UVC LED products on Amazon go, I have been told by multiple people that it is not possible to produce a UVC LED light product with a useful LED count that can sell as low as $50 or $100. If those products are scams, not only are desperate people getting cheated out of money, but the sterilization they believe is occurring is NOT, so, if they are indeed scams then the continued sales of those products actually promotes the spread of COVID-19. I kinda think that's a bad thing... ;) --- End quote --- How about a non-electronic solution? You want to test it kills bacteria so how about testing it on some harmless bacteria, such as yeast? Culture a small amount on an agar dish, expose it to the lamp, then see how much it continues to grow afterwards. --- Quote ---Part #2) I had a crazy idea to use a powerful enough UVC source to sterilize exhaled air in psuedo-real-time from infected people who need to use CPAP/BiPAP/etc for one reason or another. This includes (possibly healthy) people who normally use CPAP on a daily basis but have stopped due to warnings related to COVID-19 being expelled as an aerosol. Theoretically at least, it might be possible to do this with zero filters, which are in short supply globally. I should have a "textbook" on UVGI for surface and air sterilization tomorrow, so that should have most of the important info needed. The problem is availability of UVC sources with minimal lead time, and which ones might be suitable. I freely admit that it is Bass Ackward to design a "UVC light in a can" aka "bio reactor" based on what UVC source "just happens" to be locally available instead of the other way around. Which brings us back to products currently listed on Amazon. And back to Part #1 since anyone attempting to use UVC for something important has the same problem I'm currently facing. --- End quote --- That's not a crazy idea. I like it. There are small UVC lamps available. Something the size of a small neon indicator lamp would be good, but I've had a quick look and couldn't find anything that small. The smallest I could find is a 2W filament pre-heated mercury vapour lamp, which won't be that efficient, but still much better than LEDs. You should avoid lamps that produce ozone, which is bad for the lungs, unless there's some kind of filter to remove it. https://www.amazon.co.uk/GTL-2-Screw-Germicidal-Light-GTL2/dp/B06ZZ8GH24 --- Quote ---As for the current thread: I would appreciate recommendations on a "technical reference/textbook" that contains the right information to measure the output of UVC/radiating sources, preferably one that contains the "cheat sheet" equations to use for typical geometries so you can calculate total output based on point samples taken at specific positions around the UVC source. Hopefully I will not end up needing it, but there is a lead time so I should order it asap. Worst case it will be a welcome addition to my library. Decades ago, I vaguely recall I got a degree in EE, but after many professional years only on the software side of things... Well, saying that I have a lot of relearning and catching up to do is a gross understatement. --- End quote --- Sorry, I can't help you there. I'd just go with data sheets. If you're going to make enough of them, it might be worth talking to a manufacturer, but I expect they'll be very busy, given the current crisis. |
| james_s:
--- Quote from: Zero999 on April 05, 2020, 08:51:40 pm ---Yes go with mercury vapour for UVC. By the way nearly all modern mercury vapour lamps used for visible lighting use phosphors to boost the efficiency and are therefore really fluorescent lamps, even though they're not known as such. This is evident from the fact they're opaque/translucent white when unpowered. See the example linked below: https://www.bltdirect.com/venture-mercury-blended-lamps-delux-mbf-mbfudl-50w-e27?adcid=pla&gclid=EAIaIQobChMInZ_Kh5PS6AIVCPlRCh1EQwIDEAQYBSABEgIr2PD_BwE --- End quote --- Yes I'm well aware of this, there is a long history to phosphored mercury lamps, you can see the reddish or pinkish glow when they first start up before they warm up and appear white. The phosphor is not perfect though, only some of the UV is converted into useful light and the phosphor itself does absorb some visible light as well. You can be fooled too, I have at least one inexpensive Chinese mercury vapor lamp which is printed with the /DX (deluxe white) suffix but the coating is only a diffusing powder, it does not actually fluoresce. The best lamp related website I know of is www.lamptech.co.uk. It's an excellent site all around IMO, very good information density, clean layout without any scripts. Lots of good info without any fluff. |
| Navigation |
| Message Index |
| Previous page |