July 22, 2020

UV lamp standards

UV dosimeter
In our country, 70uw/cm2 (1m place) UV lamps account for almost 50-80%. According to the requirements of the Ministry of Health's disinfection technical specifications, the pass rate is less than 50%. The irradiation intensity of some UV germicidal lamps used per unit is less than 70uw/cm2 (at 1m). Some even less than 40uw/cm2 are still in use.

In fact, each kind of microorganism has its specific ultraviolet kill dose threshold. The bactericidal 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 UV intensity is less than 40uw/cm2, the longer the irradiation time will not be able to achieve a satisfactory sterilization effect, because there is a problem of microbial damage repair in the middle, and the irradiation intensity is deliberately increased.

As the use time of the ultraviolet germicidal lamp is extended, the radiation intensity will gradually decline. After multiple measurements, the decay rate of quartz lamps is less than 20% after 1000 hours of use, while the decay power of high-boron lamps is more than 30% after 200 hours of use, plus the radiation intensity of the high-boron lamps itself is less than 70uw/cm2 Therefore, quartz ultraviolet germicidal lamps should be used in use.

The monitoring of the radiation intensity of ultraviolet germicidal lamps is a vital task in the application of ultraviolet disinfection. The management personnel of the user unit should test the ultraviolet germicidal lamps in use, and the ultraviolet intensity should be tested in three to six months. The instrument performs an intensity test. The health and epidemic prevention monitoring department should monitor the intensity of units using ultraviolet germicidal lamps every six months, and replace the lamps with insufficient intensity in time.

The UV dosimeter should be calibrated once a year to ensure its accurate performance. When testing the radiation intensity, it must be monitored in accordance with the technical specifications of the Ministry of Health, the voltage is 220V, the temperature is 20 degrees Celsius, and the RH<60% is used for monitoring. When the intensity tester is turned on for five minutes, the tested value after the intensity is stable is the irradiation intensity of the ultraviolet germicidal lamp.