First, choose the category
There are low-pressure mercury lamps on the market, as well as LED UV lamps.
The low-pressure mercury lamp is currently the mainstream product with a life span of 8000 hours. The main wavelength is 253.7nm with high sterilization efficiency. The radiation efficiency is 18W single-ended as an example, which is above 23%, and the high power can reach 30-40%. The power is from 1W to 300W, which can meet the needs of different usage scenarios, and the light maintenance rate is high.
LEDs have long lifespan, current efficiency is low, about 3%, low power, mainly in the milliwatt level; the current mainstream wavelength is 275nm. In general, LED UVC has a promising future. It is currently suitable for disinfection in small spaces such as contact lens disinfection. Other scenarios are more suitable for experimental use by professionals due to the lack of cost-effectiveness advantages.
Second, choose materials
Take the mainstream product low-pressure mercury lamp as an example. There are two types of low-pressure mercury lamps on the market: quartz tubes and high boron glass.
Quartz tube ultraviolet germicidal lamp:
1. The material with the highest ultraviolet transmittance can transmit more than 90% of 253.7nm ultraviolet rays;
2. High ultraviolet intensity, long life, low light decay, good sterilization effect, lamp life is generally greater than 8000 hours.
High boron tube ultraviolet germicidal lamp:
1. High boron glass can only transmit about 50% of 253.7nm ultraviolet light;
2. Its ultraviolet radiation intensity is small and its life span is short. Several established international companies are doing well, such as Philips/OSRAM.
Third, choose whether to contain ozone
Quartz UV lamps are divided into ozone and ozone-free.
Need to make a choice for specific use scenarios. Such as disinfection box or warehouse goods disinfection, need to use ozone. (Note: Because ozone is harmful to cultural relics/calligraphy and painting, etc., you need to consult a professional before using it.)
Doped (Ti, Ce) quartz glass for ozone-free ultraviolet lamps;
Natural quartz glass, used for ozone ultraviolet lamps;
Synthetic quartz glass, with higher cost, is used for ultraviolet lamps with higher requirements. General household use. Don't choose the ozone function, which is harmful to human health.
Fourth, choose power
For space disinfection, one square can be configured with 1W, and for high-demand ones, one cubic can be configured with 1.5W. Taking the floor height of 3 meters as an example, 4.5 watts per square meter is required.
Dosage considerations
The structure of the pneumonia coronavirus is similar to that of the SARS virus, and it is also sensitive to ultraviolet radiation. In the later period of SARS in 2003, CCTV pointed out in a corresponding report: 30-watt ultraviolet light, at a distance of 1m, will kill the virus in 30 minutes. The ultraviolet illuminance at 1 meter is 90 microwatts/square centimeter. The dose is: 90X30X60=162,000 microwatts·sec/square centimeter Illuminance*time=ultraviolet energy value.
