What you need to know about UV lamps

A sudden epidemic has disrupted everyone’s rhythm of life, and everyone had a unique Spring Festival. But at the same time, the epidemic has also made more and more people start to pay attention to personal hygiene. In addition to wearing masks when going out, the importance of disinfecting the home is also becoming more and more important.

The most common, naturally, is the use of alcohol and disinfectant for indoor disinfection. But the actual use of it has a number of hidden dangers. The first is 75% concentration of alcohol, as we all know, alcohol is extremely flammable, not to mention touching an open flame, is the current dry In winter, all the static electricity that is inadvertently generated can be extremely dangerous. As for disinfectants, and if there are pets in the house, whether it’s 84 disinfectant, or its phenol-based disinfectant, the damage to pets’ It’s also huge.

In addition to 75% alcohol and various types of disinfectant, there is actually a great way to disinfect using a UV lamp. Of course, UV lamps are currently a scarce product, just like masks and disinfectants, and can be difficult to purchase in a short period of time . But that’s okay, before we get to that, let me tell you about how UV lamps disinfect, how to choose, and what you need to do to use them. What questions to pay attention to. What is UV? The so-called ultraviolet light, is the spectrum of 100-400 nanometers of light, between X-rays and visible light. Depending on the wavelength, ultraviolet light is further divided into UVA, UVB, UVC and UVD, of which medium and long wavelength ultraviolet light can be found here. We’ll skip the discussion and focus on shortwave ultraviolet (UVC) as well as vacuum ultraviolet (UVD).

UVC short-wave ultraviolet, a type of ultraviolet light with wavelengths between 200 and 280 nanometers, has very little penetrating power and ordinary glass and plastic products can be easily blocked. But its killing ability is very strong, sterilization is the use of this point, and can not directly irradiate the human body. Another kind of UVD vacuum ultraviolet ray, the wavelength is between 100-200 nm, the penetration ability is very weak, but can make the air The oxygen oxidation to ozone. Ultraviolet lamp disinfection principle ultraviolet lamp main working principle, is to use the release of ultraviolet light, to bacteria, virus inactivation. In order to achieve the role of sterilization disinfection. And specific to the ultraviolet lamp specific working principle, should mention the ultraviolet lamp light source, at present mainly by two light sources: gas discharge Light sources and solid state light sources. We are usually able to buy mostly ultraviolet lamps of the gas discharge light source type, primarily low pressure mercury lamps. They work on the same principle as fluorescent lamps, except that the mercury vapour in the lamp is charged and the mercury atoms in the tube are electrically excited to produce ultraviolet light. Low-pressure mercury vapor generally produces mainly 254nm UVC ultraviolet and 185nm UVD ultraviolet.

The 254 nm UVC destroys the DNA and RNA molecular structure of microbial cells, causing cell death and sterilization.

And 185nm UVD ultraviolet although does not have the effective sterilization effect, but it can decompose the oxygen in the air, generate ozone. The strong oxidizing properties of ozone can oxidize the enzymes needed to break down the glucose inside the bacteria, killing the bacteria to sterilize and disinfect them. When you go to an e-commerce platform to pick out a UV lamp, you’ll find that almost all UV lamps will have both ozone-functional and non-ozone The functional version, which is actually because of how UV lamps work.

The other solid-state light source is the UV-LED light source, although the size is small, but compared to the above low-pressure mercury lamp efficiency is much lower, and because of the cost, the price is also very expensive, will generally be used in water purifiers, air conditioning and other equipment inside, such as Dyson’s humidifier, here will not start.

How to choose the suitable power?

UV lamp

Typically, 1 cubic meter of UV light should be no less than 1.5 W. Based on this, let’s say your bedroom is 20 square meters. The floor height is 3 meters, so a simple calculation shows that you need a 40W UV lamp for your bedroom. A rough calculation based on your own home is probably about right, it doesn’t need to be that precise.

Another thing to pay attention to is the material of the lamp, there are two main glass materials on the market for low pressure mercury lamps: quartz glass and high boron glass. The transmittance and radiation of quartz glass is higher than that of high boron glass. As mentioned before, short-wave UV rays have very little penetrating power, so be sure to choose quartz glass.

In addition, there are now on the market a number of smaller portable ultraviolet lamp, although the power is lower, but can be closed to the wardrobe, refrigerator and other small space for disinfection, is also a good choice, you may wish to consider.

Is the ozone function is necessary? The average home will have a variety of furniture and debris that will block the spread of UV rays, so it’s usually advisable to go with an ozone-containing The ozone can pass through the air flow to sterilize some dead spots. However, ozone is harmful to the human body, and after disinfection, windows should be opened for 30-60 minutes until the pungent smell of ozone is gone. For Stop.

As mentioned earlier, low-pressure mercury lamps normally produce UV in both the UVC and UVD wavelengths, and it can be argued that ozone is a doomed Will produce. And on the market which does not carry ozone ultraviolet lamps, in fact, the real lamp increased the coating, to block 185nm wavelengths. UV in order to avoid ozone production. But this also contributes somewhat to the efficiency of 254nm band UV transmission, so unless you don’t have open windows for ventilation. Otherwise, it is still recommended to opt for a UV lamp with ozone function.

For this COVID-19, how long does it take to disinfect?

covid

The guidelines issued by the CDC state only that “UV light can inactivate the new coronavirus” but do not mention how long it takes to inactivate it. How long does it need to be disinfected when it is actually in use? Let’s take an example.

A typical brand new 30W UV lamp has an irradiation intensity of 90-100μW/cm² at 1 meter. According to a 2003 study by Dong Xiaoping, a research team of experts from the Institute of Virus Prevention and Control of the Chinese Center for Disease Control and Prevention, an intensity greater than 90 μW/cm² of UVC irradiated with SARS coronavirus will kill the SARS virus in 60 minutes. Referring to this standard, you can essentially just follow the maximum dose and irradiate for 60 minutes at a time to disinfect.