Does the uvc indicator at the top need to show a green color to confirm the presence of uvc? i saw a white color when directly in front of led

The bright green is what we want to see along with word visibility at the bottom. I am changing the answer to your question after talking to our lead engineer. Ok, first the good news, real UV-C wavelengths are present for the letters UV-C to be visible at all. But there is a party going on in there too. Led's used in disco lights and those for detecting cat pee in the 395nm range can not cause fluorescence in the molecules in the UV-C test area. Yet, I say there is a party going on because it takes a blacklight's wavelength to greatly change our visual perspective of the colors that reach our eyes (the same way a blacklight changes the reflected colors in a room). The color green is the only color being emitted by the fluorescent analyte in the wavelength test which makes the letters UV-C visible. However, toss some LED party lights into the mix, and our perception of the true reflected color will change. It is not uncommon at all to see dubious manufacturers include many UV-A and UV-B LEDs into their so-called UV-C LED light arrays. Some models have 12 LEDs on the top and 12 LEDs on the bottom, but only two LEDs are real UV-C in what can be considered optimal UVGI wavelengths. Recent studies on the sun's effect on the virus focused on UV-A and UV-B wavelengths which showed to be helpful but not to be considered anywhere close to optimal germicidal wavelength to inactivate a virus. Excessive UVA and UVB light produced from a sanitization device should be a huge red flag! The answer continued below...

How many times can this be used?

When correctly stored away from UV light and high humidity, the short answer is hundreds of times at 300 microwatts mercury-line UV-C exposure for a duration of 15-seconds each use as directed. The wavelength indicator in Step one, the top test area of the QuantaDose, does not degrade easily, so the test card will continue to detect mercury-line germicidal wavelengths of UV-C by glowing green letters as long as the specialized narrowband analyte is on the UVC test card. Step two is different. The photochromic material used for the lower intensity test area has a life span because of photo-degradation effects that affect photochromic materials. The main factor for how many times you can reuse the lower test area is the accumulative amount of exposure to UV radiation and NOT the number of times the photochromic material is cycled between exposures. Keeping the exposure times to a maximum of 15 seconds limits the photo-degradation effects on the photochromic material by decreasing unnecessary accumulative UV exposure. If you were to expose the test card twice as long as recommended, i.e., 30 seconds, you could expect half the life span. I’ve personally left one under confirmed UVC lights over 2 hours at 300 µW/cm², which would equate to 480 times used in 15-second intervals, and the card was still plenty reuseable. I’ve also left one in direct sunlight under the noontime sunshine in Florida, and the lower test area was completely burned out 2 hrs later. The longer wavelengths of UVA and UVB from the sun can penetrate the photochromic material much deeper. Thus, photo-degradation effects happen quicker in the natural sun than under short wave UVC’s much more energetic wavelengths with less penetrating power. Many variables contribute to accumulative UV exposure because everyone uses various wattage and wavelength devices for disinfection. One person can be testing 3-watt UVC bulbs while another is testing 60-watt bulbs – the wavelength, time exposed, and distance from the source are all factors for accumulative exposure. So as first mentioned, the short answer: It would be safe to assume the UV-C light tests can be performed hundreds of times if adequately stored and UVC exposure is limited to 15 seconds intervals at between 300-500 µW/cm² for each test. If you have any doubt about the lower test result of a new QuantaDose card because a UVC device doesn't have enough power to display the word “ULTRAVIOLET” (@300 µW/cm² 254.7nm) in step two, simply hold the test card in direct sunlight to confirm a near-instant UVA/UVB wavelength reaction. The QuantaDose UVC Test card is much like any other measurement device with a finite life span for accuracy. To maintain the accuracy of any measurement device that is reusable, which also has a finite life span, requires a calibration procedure. The QuantaDose UVC test card is straightforward to test, providing you have a known source of UVC power and distance. If you don't have a UVC meter or known source of power when you first get your QuantaDose card hold it in sunlight for 15 seconds and take a picture with your phone. After a couple of hundred 15 second tests or so, hold it in the sun again for 15 seconds to see if it is a full-color shade lighter compared to the original picture. This makes it easy to see any photo-degradation effects over time. For something more precise we recommend using a 3-watt UVC wand (Known Source) as these are the least expensive noted in our product listing. Just hold the 3-watt bulb 1 inch away to confirm word visibility occurs in 15 seconds. Calibration with a UVC meter is the most exact. This is an option for people with professional UVC light meters who use the QuantaDose to test in areas their meter probes can not get into.

Does the uvc/ultraviolet text remain for a few seconds after exposure is stopped? i'm trying to test a closed-box sanitizer.

There is a temporary result to check intensity after exposure that will last between 5 and 15 seconds depending on how much power the device emits. QuantaDose UVC test is a two-step test for a meaningful germicidal test result. IMPORTANT: You can't use color change in STEP 2 (UVC intensity test when the word ”ULTRAVIOLET” first becomes legible in lower area) until you have completed STEP 1 (confirm UVC wavelength when the letters ”UV-C” glow green in the upper test area) If the UV sterilizer is big enough, you might just want to consider propping up your phone to record the test to confirm STEP 1 that the device is using genuine UVC light indicated by the UV-C letters glowing green. The glowing UV-C will only glow when exposed to UVC light and must be confirmed before using the lower intensity test area. After you have confirmed that STEP 1 confirms the device is in fact UVC light. STEP two can be done without your phone. This part of the test gives you a few seconds to view the result as long as it has reached the minimum intensity of > 300 µW/cm² Simply run the device for not much longer than 15 seconds, open the device, and check to see if the word ”ULTRAVIOLET” is legible in the lower test area. The word ”ULTRAVIOLET” being legible confirms a minimum UVC intensity of 300 µW/cm² which is acceptable for UVC disinfection when step 1 is confirmed. The Quantadose test card is a two-part test to confirm the minimum power of 300 µW/cm² when the word “ULTRAVIOLET” first appears visible in the lower intensity test area while the green UV-C is glowing in the upper part. As long as you can confirm step 1 with your phone, step 2 will remain visible long enough to open the device to confirm the intensity of UVC is trustworthy for a germicidal application. The reason you must confirm step 1 is that if the device is using UVA and UVB light the lower test area will still change color, in fact, UVA and UVB will cause the color to be much darker than UVC shorter wavelength, and the legibility of the word ”ULTRAVIOLET” is only calibrated for > 300 µW/cm² for the mercury line spectrum of UVC at a peak 253.7 nm wavelength. If you have any questions about the process of testing UVC wavelength and UVC intensity for any device our engineers can help walk you through the process of validation over the phone. Our contact details can be found on our Quanta X Technology Amazon sellers page Blessings, Katie Webb

When i put card inside a uvc light bag, and turn it on, i can see "uvc" in purple through viewing window on the bag. does that prove bag emits uvc?

"UVC" should be lighting up in green in the top box which would indicate that it is detecting UVC light. The lower box should turn purple with "Ultraviolet" visible in white lettering. The shade of purple can be compared to the scale under the box to determine the intensity of the light. If you are not seeing the "UVC" in green in the top box and only the bottom box turning purple with "Ultraviolet" visible, that means your light bag is emitting only UVA and/or UVB light, not UVC light.

Manufacturer	Quanta X Technology LLC
Part number	QXT0022020QD
Item Weight	10 g
Product Dimensions	8.6 x 5.4 x 0.08 cm; 10 g
Item model number	QXT0022020QD
Material	PVC
Item Package Quantity	1
Batteries included?	No
Batteries Required?	No

2nd Gen QuantaDose® Reusable UVC Light Test Card with UV Intensity Strip Sensitive to UVA/UVB/UVC Light

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