Hello there,
A question came up as to whether or not a UVc light 'bulb' i have is really UVc or some other UV grade. The 'bulb' says on the side, "UV Germicidal Lamp".
Now i know that sounds good, but wavelengths other than 265nm also kill some germs but to get more of them you really need 265 or thereabouts, or shorter (180nm for example). UV also covers 405nm but hat's not as effective.
So i was thinking of a way to test this light. If it was a tube i might not think about it as much but it is made of a lot of LEDs that are supposed to be UVc LEDs. When i look all over the web i cant find one UVc LED that looks like these though. A test would tell me right away.
Now from what i understand, the forward voltage of a 265nm is quite a bit higher than for a 406nm LED. The voltage is around 7v with a 5v minimum for lower current, and for 405nm it could be as low as 3v to maybe 5v as a maximum.
So UVc 265nm has roughly 5v to 7v or so, while the 405nm has roughly 3v to 5v. That is enough to measure.
However, measuring the voltage is not that easy because of the mounting of the SMD parts, which would either require soldering to the ends of the LED or trying to hold two probes on the bulb while someone else turns it on.
Either of which i dont want to do.
So i looked into this, and you can buy 'cards' that test for UV light, but i think the ones that test for UVc are quite a bit expensive while the regular UV ones are only around 9 dollars USD. Looking up a few other things like UV activated epoxy, i found that the epoxy hardens with a lower frequency light (longer wavelength like 400nm) and it should not react much to 265nm.
So, putting a dab of the epoxy on a stick and holding up to the 60watt LED 'bulb' and turning it on with eyes blocked completely, i exposed the dab of epoxy for about 10 seconds. Amazingly, it did not harden or even seem to change consistancy. To be sure, i then exposed the dab to a UV light that normally is used to harden the epoxy in around 3 seconds. Holding the light above the dab, it harden rock hard leaving it exposed for about 5 seconds.
So what do you think. You think this is a good enough test? I suppose the light wavelength could be longer than 405nm but then i would think it would be a total fake, and might appear too visible. However, the lamp does appear to be a bight blue white color when turned on.
Also, when i price the UVc LEDs on the web they run 8 to 12 dollars USD or more, while the 405nm LEDs are only about 2 dollars USD, and i only paid 35 dollars for one of these bulbs and they have at least 100 LEDs on the sides and bottom.
So you think that was a good enough test or do you know of a cheap reliable UVc measuring card or device?
A question came up as to whether or not a UVc light 'bulb' i have is really UVc or some other UV grade. The 'bulb' says on the side, "UV Germicidal Lamp".
Now i know that sounds good, but wavelengths other than 265nm also kill some germs but to get more of them you really need 265 or thereabouts, or shorter (180nm for example). UV also covers 405nm but hat's not as effective.
So i was thinking of a way to test this light. If it was a tube i might not think about it as much but it is made of a lot of LEDs that are supposed to be UVc LEDs. When i look all over the web i cant find one UVc LED that looks like these though. A test would tell me right away.
Now from what i understand, the forward voltage of a 265nm is quite a bit higher than for a 406nm LED. The voltage is around 7v with a 5v minimum for lower current, and for 405nm it could be as low as 3v to maybe 5v as a maximum.
So UVc 265nm has roughly 5v to 7v or so, while the 405nm has roughly 3v to 5v. That is enough to measure.
However, measuring the voltage is not that easy because of the mounting of the SMD parts, which would either require soldering to the ends of the LED or trying to hold two probes on the bulb while someone else turns it on.
Either of which i dont want to do.
So i looked into this, and you can buy 'cards' that test for UV light, but i think the ones that test for UVc are quite a bit expensive while the regular UV ones are only around 9 dollars USD. Looking up a few other things like UV activated epoxy, i found that the epoxy hardens with a lower frequency light (longer wavelength like 400nm) and it should not react much to 265nm.
So, putting a dab of the epoxy on a stick and holding up to the 60watt LED 'bulb' and turning it on with eyes blocked completely, i exposed the dab of epoxy for about 10 seconds. Amazingly, it did not harden or even seem to change consistancy. To be sure, i then exposed the dab to a UV light that normally is used to harden the epoxy in around 3 seconds. Holding the light above the dab, it harden rock hard leaving it exposed for about 5 seconds.
So what do you think. You think this is a good enough test? I suppose the light wavelength could be longer than 405nm but then i would think it would be a total fake, and might appear too visible. However, the lamp does appear to be a bight blue white color when turned on.
Also, when i price the UVc LEDs on the web they run 8 to 12 dollars USD or more, while the 405nm LEDs are only about 2 dollars USD, and i only paid 35 dollars for one of these bulbs and they have at least 100 LEDs on the sides and bottom.
So you think that was a good enough test or do you know of a cheap reliable UVc measuring card or device?