How to Select the Best UV Light Meter For Your Application？

According to different biological effects of ultraviolet rays, ultraviolet rays can be divided into the following four bands according to the wavelength. The current LS125 multi-probe UV light meter is also mainly classified according to the three bands of UVA, UVB and UVC.

(1) UV-A band

The wavelength is 315-400nm, also known as long-wave black spot effect ultraviolet rays. UVA has a strong penetrating power and can penetrate most transparent glass and plastic. More than 98% of the long-wave ultraviolet rays contained in sunlight can penetrate the ozone layer and clouds to reach the earth's surface.

(2) UV-B band

The wavelength is 280 ~ 315nm, also called medium wave erythema effect ultraviolet. Its shorter wavelength will be absorbed by transparent glass. Most of the medium-wave ultraviolet rays contained in sunlight are absorbed by the ozone layer and only less than 2% can reach the surface of the earth. It will be particularly strong in summer and afternoon.

(3) UV-C band

The wavelength is 200-280nm, also known as short-wave sterilization ultraviolet. It has the weakest penetrating power and cannot penetrate most transparent glass and plastic. The short-wave ultraviolet rays contained in sunlight are almost completely absorbed by the ozone layer.

(4) UV-D band

Vacuum ultraviolet light, with a wavelength of 100 ~ 200 nanometers, has very weak penetrating ability and it can oxidize oxygen in the air to ozone.

UV intensity units are mainly μW / cm², mW / cm², W / cm² and W / m².

Conversion of UV intensity unit: 1W / cm² = 1 × 10 ^ 3 mW / cm² = 1 × 10 ^ 4 W / m² = 1 × 10 ^ 6 μW / cm²

The multi-probe UV light meter LS125 independently developed by Linshang Technology provides multiple units to choose from. Users can choose the corresponding unit according to their own measurement needs.

During sterilization, if the intensity of UV radiation is high enough, the inactivated virus bacteria will not be revived. But if the radiation intensity is too low, the virus bacteria inactivated by UV radiation can repair the damaged structure by light. Therefore, an UV light meter is needed to ensure that the irradiation intensity of the ultraviolet disinfection lamp is higher than the standard value.

"WST 367-2012 Regulation of disinfection technique in healthcare settings" stipulates that after turning on the UV germicidal lamp for 5 minutes, the probe of the UV light meter with a measuring wavelength of 253.7nm needs to be placed at a vertical distance of 1m directly below the tested UV lamp (special UV lamp needs to be placed at the recommended distance for measurement. The data shown after the UV light meter is stable is the irradiance value of the UV lamp).

The standard of ordinary 30W straight tube type ultraviolet lamp is as follows: the irradiation intensity of the new lamp should meet the requirements of GB 19258; the use of ultraviolet lamp irradiation intensity ≥70μW / cm² is qualified; the irradiation intensity of 30W high intensity ultraviolet lamp ≥ 180μW / cm² is qualified.

The length of UV sterilization needs to be treated differently depending on the type of bacteria or virus that needs to be killed. Ultraviolet radiation dose = ultraviolet radiation intensity × light duration. Only when a certain amount of UV radiation is reached can certain bacteria or viruses be killed.

Take the influenza virus as an example. To reach 99% inactivated influenza virus, a UV irradiation dose of 6600 µWs / c㎡ is required (the true UV irradiation dose unit is mJ / c㎡. In order to calculate the duration of the light, the unit is converted into µWs / c㎡). If a 30W straight tube medical sterilization lamp with an irradiation intensity of 90µW / c㎡ is used for sterilization, the duration of irradiation is 6600 ÷ 90≈73s, which is 1 minute and 13 seconds.

Taking over-flow sterilization equipment as an example, the principle of sterilization of ultraviolet germicidal lamps in water is such that the water flows through the periphery of a quartz tube that can penetrate ultraviolet rays, and the 254nm ultraviolet rays generated by ultraviolet lamps sterilize and sterilize water. Due to the rapid flow of water, the time it takes for the water to flow through the quartz jacket is no more than 1 second, so only high-intensity and high-power UV lamps can achieve the conventional sterilization effect, and the power of the UV lamps needs to be measured regularly with an UV light meter. 

If the UV light meters are used too frequently or after a certain period of time, a certain degree of aging will occur. For example, the internal filter may be mildewed due to the humid storage environment. In addition, many factors may affect the accuracy of ultraviolet radiation intensity measurements. Therefore, it is recommended to periodically calibrate the UV light meter. The recommended calibration cycle is one year. Users can adjust the calibration cycle according to their own frequency of use and the accuracy of the instrument.

Institutions and hospitals can send UV light meters to regular third-party metrology agencies if they need to be calibrated before using medical UV light meters. If it is only necessary to ensure the accuracy of the measurement data, we recommend that custometers send the uv light meter back to the manufacturer for calibration. The UV light meter manufacturer can provide a recalibration report, but cannot provide an authoritative certification report.

The UV light meter can measure the power (intensity) or energy value of the received UV. Ultraviolet is an electromagnetic radiation that has a shorter wavelength than visible light, but a longer wavelength than X-rays. The ultraviolet sensor can convert one energy signal received into another energy signal and the output signal is an electrical signal; The built-in analog-to-digital conversion chip (ADC) can convert the weak current signal into a digital signal. The digital signal collected by single-chip microcomputer will be adjusted and recorded.The obtained power value will be used to calculate the UV energy value or generate other graphics and measurement reports.