Principles and hazards of UV disinfection
UV light is a wavelength of 16 to 397 nm electromagnetic waves, of which only 240 to 280 nm wavelength ultraviolet light has a strong bactericidal effect, generally as a representative of 253.7 nm UV germicidal ultraviolet rays. UV has a strong bactericidal, can kill a variety of bacteria (including Mycobacterium tuberculosis ) , fungi , viruses , as well as physical and chemical factors resistant to bacterial spores. And easy to use, low cost, small damaged goods , etc., are widely used in medical , health, food , pharmaceutical and other sectors disinfection.
UV lamps for disinfection straight tube type, H -type and other shapes of lamp power are not the same , there are 40W, 30W, 20W, 8W there even smaller . Most lamps will produce ozone during irradiation , ozone , said ultraviolet light , and some do not produce ozone during irradiation , saying no ozone ultraviolet light, they are made with different uses ultraviolet disinfection . Ultraviolet radiation on human skin, eye injuries, can not direct exposure to the skin when used, the eyes can not look directly at the UV light , ozone using ultraviolet light should also pay attention to human toxicity of ozone disinfection .
UV disinfection for air
The most commonly used UV and most effective way is to use air disinfection , widely used in wards, preparation room , treatment rooms , operating rooms , laboratories , etc. The air disinfection. UV air disinfection method used more, the most common is the direct UV lamp hanging in the room, the number of UV lamps installed in 1W/m3 appropriate. When installing multiple lamp reflectors installed , there are two methods to install reflectors , reflector down common is mainly used in the sterilization of unmanned , not directly irradiated UV reflector up exposed skin , eyes not directly visible , it can be used in air disinfection.
There are portable ultraviolet irradiation, ultraviolet light is not fixed in the room, when the indoor air requires disinfection, ultraviolet disinfection of vehicles or other ultraviolet disinfection unit moved indoors disinfected after the removal of the UV disinfection of vehicles , a decontamination vehicle available in multiple rooms disinfected.
In recent years also developed a variety of UV air disinfection machine circulating air , to strengthen disinfection , sterilization machine which increased circulating air filtration , anion and other functions , mainly for indoor air at the time of continuous disinfection, sterilization in addition to outside , also has a certain air purification, can reduce the concentration of airborne smoke , CO, CO2 and other harmful gases.
Under the situation when someone in air disinfection , do not use high ozone ultraviolet light, ultraviolet light may not be used direct exposure to the skin or eyes personnel methods for disinfection, ultraviolet light and easy to personnel due to skin and eye injury , ultraviolet light is not under normal circumstances Recommended for home air disinfection, UV- circulating air can be used for disinfection of air disinfection machine when necessary .
UV light can also be used appliance surfaces , coins and letters disinfection
Another effect of ultraviolet radiation on the body surface contaminants are disinfected , although with good UV sterilization function , do not damage the advantage of being sterile , easy to use . But there are very prominent drawback that the penetration is weak, only the surface directly irradiated with germicidal effect , is not directly irradiated to the place, no bactericidal effect. This is only for ultraviolet radiation hard surface disinfection reasons. If you want to use it to clean paper , letters, must be a page , a picture of each irradiation sterilization. Since UV can not penetrate , is not suitable for such items disinfected.
UV disinfection with ultraviolet radiation intensity of high- intensity ultraviolet radiation , good sterilization effect, the radiation intensity is weak, poor disinfection . Irradiation with UV light irradiation intensity is inversely proportional to the distance , the closer , the stronger the radiation intensity , on the contrary , the irradiation intensity weaker . So to disinfect surfaces should be disinfected direct exposure to ultraviolet light , the closer , the greater the radiation intensity , disinfection better.
The human eye can not see ultraviolet light , so the strength of the strong ultraviolet radiation can be used in Germany KUHNAST UV-365A UV radiation meter to test .
Under normal circumstances, with a 30W UV lamp irradiation , at the bottom of the vertical 100cm , irradiation for 30 to 60 minutes , can kill dysentery, Pseudomonas aeruginosa and other bacteria and influenza viruses , hepatitis viruses , to achieve disinfection requirements. Irradiation distance increases, sterilization time should be extended.
UV can also be used for water disinfection
Ultraviolet radiation on microorganisms in water also kill, and no residue after disinfection , without the formation of harmful substances can be used to disinfect drinking water, sewage , etc. . However, due to the weak penetration of ultraviolet rays , brachytherapy only superficial kill microorganisms in the water , on the deep microbial no role in the killing . So when disinfecting water depth of not more than 2cm, the flow rate should not exceed 3.6m3 / h. Family is difficult to directly use the disinfecting UV lamp . Existing proprietary UV water sterilizer can be selected according to need .
Penetrating weak because the ultraviolet , ultraviolet not penetrate plastic or glass , it can not penetrate the flexible packaging material , packaging material but can not penetrate the metal , and therefore unsuitable for bottled water disinfection beverage packaging . Not suitable for milk, juice and other beverages , such as viscous disinfection .