Measurement of ultraviolet illumination and ultraviolet lamp radiation intensity
1. The radiation intensity of ultraviolet lamps:
In China, the ultraviolet lamps with 70 uw/cm2 (at a distance of 1m) account for almost 50-80%. Compared with the requirements of the Ministry of Health’s disinfection technical specifications, the pass rate is less than 50%. .Some are still in use even less than 40uw/cm2. You should know that each microorganism has its specific ultraviolet killing dose threshold. The killing dose (K) is the product of the irradiation intensity (I) and the irradiation time (t) , K=It. It can be seen from the formula that high-intensity short-time or low-intensity long-term irradiation can obtain the same sterilization effect. However, if the ultraviolet intensity is less than 40uw/cm2, then extending the irradiation time will not be satisfactory. The sterilization effect, there is a problem of microbial damage repair in the middle, and the main purpose is to increase the irradiation intensity
Second, the spatial range of ultraviolet radiation:
Many units that use ultraviolet germicidal lamps ignore the effective space range of ultraviolet radiation, and only consider and calculate the plane area of radiation. In addition to the area factor, each disinfection space has high and low heights, and the total space range varies. Small, the use of germicidal lamps should calculate the total space cubic and use ultraviolet germicidal lamps of corresponding power. The effective disinfection space range of a 30w germicidal lamp should be less than 30 cubic meters. It is generally believed that the power of germicidal lamps per cubic meter of space should be greater than 1-1.5w, it should be noticed in use.
3. Irradiation distance of lamp suspension:
When using a germicidal lamp, attention should be paid to the irradiation distance between the object to be sterilized and the germicidal lamp, that is, the hanging height of the lamp tube should be less than 2.5 meters. Some units that use the lamp tube have a hanging height greater than 2.5 meters, or even greater than 3 or 4 meters. Ultraviolet The irradiation intensity is almost inversely proportional to the irradiation distance, if the suspension is too high, it will inevitably affect the sterilization effect.
Fourth, the decline of ultraviolet radiation intensity:
With the prolongation of use time, the radiation intensity of ultraviolet germicidal lamps will gradually decline. According to various measurements, the decline rate of quartz lamps is less than 20% after 1000 hours of use, and the decline rate of high boron lamps is greater than 30% after 200 hours of use. , plus the radiation intensity of the high boron lamp itself is less than 70uw/cm2, so quartz ultraviolet germicidal lamps should be used in use. The characteristics of quartz ultraviolet germicidal lamps are mainly high radiation intensity and slow decay. The raw material of quartz lamps is natural crystal stone, and the purple transmission rate is more than 80%, while the purple transmission rate of high boron glass is less than 50%. The rate is low, and the radiation intensity is also low.
Five, the application should also pay attention to the wiping and cleaning of the lamp tube:
When using a new lamp, you can wipe the lamp tube with 75% alcohol gauze first. Dust and oil stains will pollute the lamp tube. During use, wipe it regularly and do a good job of cleaning the lamp tube so as not to affect the purple transmission rate and radiation intensity. .
