Ultraviolet radiation is a kind of electromagnetic radiation and is a kind of invisible light, so it is also called ultraviolet light. The germicidal effect of UVC has been discovered more than 100 years ago. UVC has been used directly for disinfection for nearly 100 years. Although many methods of disinfection have been discovered in the years since then many disinfection methods have been discovered since then, UVC is still an ancient disinfection method that is still widely used for sanitation and hospital disinfection. In recent years, due to the development of science and technology UV disinfection technology has also seen new advances. A variety of new UVC disinfection devices have been developed equipment, improved UVC germicidal lamps, further research on the rational use of UVC disinfection technology Further research on the rational use of UVC disinfection technology and UVC disinfection effect monitoring methods.
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1 UVC disinfection effect
The average kill rate of E. coli and S. aureus was more than 99.9% when different bacteria were contaminated with 105-106 CFU/tablet on a glass sheet and irradiated by a 30 W UV lamp with radiation intensity of 70 μW/cm2 for 3 min; the kill rate of Bacillus subtilis black variant for 15 min was also more than 99.9%; the kill rate of Candida albicans 99.9% required 100 μW/cm2 for 3 min. In the laboratory, a 30 W UV lamp with a power of at least 1.5 W/m3 is installed and irradiated for 30-60 min to kill more than 90% of natural bacteria in the air.
2 UV disinfection applications
UV disinfection is an effective, economical, convenient, and safe method, so it is widely used in all walks of life. In recent years, research and improvement have made UV disinfection more scientific and reasonable, more convenient to use, and more reliable.
1) Indoor air disinfection
UV disinfection is the most convenient method of air disinfection. There are three main methods of disinfection, fixed irradiation method, mobile irradiation method, and indirect irradiation method.
2) Surface disinfection of contaminated objects
UV light has a certain effect on surface disinfection, especially for smooth surfaces The effect is better. It can be used for indoor surface disinfection, equipment surface disinfection, and special equipment disinfection.
3 Effect monitoring
UVC lamps with the use of time to extend the radiation intensity decay and its germicidal effect will be affected by many factors. The results are also affected by many factors, so regular monitoring of UV lamps is an important measure to ensure their effective use. Therefore, regular monitoring of UVC lamps is an important measure to ensure their effective use. Therefore, regular monitoring of UVC lamps is an important measure to ensure their effective use. UVC disinfection is usually monitored using biological, physical, and chemical methods. biological, physical, and chemical methods, all three of which have been written into national disinfection All three methods have been written into national disinfection specifications.
1) Biological methods
The biologic method uses live microorganisms as indicators of UV killing ability and is therefore relatively straightforward. It is more intuitive and has practical value in the study and application of UV disinfection. The strict method is difficult to implement in hospitals because of the strict technical requirements, the complexity of the operation, and the slow results. It is difficult to implement in hospitals.
2) Physical methods
The use of certain UV-specific sensitive components of the “UV radiation illuminance meter” can directly determine the intensity of UV radiation from UV germicidal lamps and indirectly determine the ability of UV germicidal. When equipped with photosensitive components of the photoreceptor to receive ultraviolet radiation, the light signal is converted into an electrical signal, through the signal transmission amplification by the instrument to indicate the reading value or into a digital signal directly by the instrument window to display the number. Turn on the UV lamp, debug the voltage and zero points of the UV radiation illuminance meter; open the cover of the photoreceptor, it will be placed under the UV lamp vertical 1 m to receive irradiation; wait for the digital window of the illuminance meter to stop changing the digital can read the value; record the reading at the time, the end of the test, the illuminance meter switch back to the position, cover the cover of the photoreceptor.
- Dedicated storage, dedicated use. Ultraviolet intensity meter needs to be used by a person to maintain, regularly sent to the designated department standard test calibration (domestic instruments require annual standard test), and develop a protocol for use. Instruments should be stored in a dry cabinet after use, especially the measurement probe to prevent moisture, shock, mold.
- Standardized use. Before use should first carefully read the instruction manual, according to the specified measurement data, such as in the power supply voltage qualified, in the UV lamp 1 m below the vertical, open the UV lamp for 5 min after the measurement.
- Repair and maintenance. If you suspect that the instrument is faulty or out of time, do not disassemble it yourself, do not adjust at will, you need to ask professionals or directly contact the manufacturer to repair and calibrate.
- Pay attention to protection. The personnel performing the test need to take certain protective measures, such as wearing overalls, white gloves, and protective glasses, so as not to expose human eyes and skin directly to ultraviolet light.
3) Chemical methods
Because the physical monitoring method requires instruments, the one-time investment is relatively large, so China Combined with the national conditions of the first ultraviolet radiation intensity chemical determination method. Certain UV-sensitive chemical substances (such as chlorinated polymer compounds) are combined with certain excipients to make a chemical method. Specific sensitive chemical substances (such as chlorine-containing polymer compounds) and certain auxiliary materials to make The printing ink is made by choosing special paper and coating the ink evenly on the paper to make photosensitive paper. The two ends of the card paper printed on the standard color block that one end of the new factory lamp minimum standard radiation intensity and the minimum allowable radiation intensity of the lamp in use two standard color block, in the center of the card paste The center of the card is attached to the photosensitive paper is made to indicate the card. The card is made of photosensitive paper in the center. After the UV lamp was turned on for 5 min, the front side of the card was turned toward the UV lamp. After the UV lamp is turned on for 5 min, the front side of the indicator card is turned toward the UV lamp and irradiated for 1 min at a distance of 1 m from the center of the light source. The reading was taken immediately. The painted block changed from light yellow to dark purple, compared with the standard color block, and recorded UV lamp radiation intensity ≥ or ≤ 70 μW/cm2 or ≥ 110 μW/cm2. The UV Radiation intensity chemical indicator card is only suitable for routine monitoring, monitoring results can only conclude Whether the factory is qualified, whether the lamp in use can continue to use; indicator card can only be monitored at the time of reading and recorded in time, and subsequently, The indicator card can only be read at the time of monitoring and recorded in time, then the color block will fade and can not be repeated after fading use . The unused indicator cards should be wrapped in black photo paper, protected from light and moisture, and preferably The unused cards should be wrapped in black paper, protected from light and moisture, and preferably stored in a refrigerator at 4°C.
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