Since UV based technology is not perceptible on its own, manufacturers often add color to UV radiation (e.g. by means of LEDs), thus allowing people to see whether a UV based lamp is on. Among other things, this is done to prevenet users from being exposed to harmful UV based light. But LEDs are not the only way to show whether a UV technology lamp is on. The presence and effectiveness of UV based radiation can also be measured in other ways, namely with light meters.
It's important that the UV based tech reaches the entire surface of the area it's disinfecting. It's also very important for hospitals, care institutions and laboratories that the correct disinfection values be attained, to ensure the reliability of their staff and patients. If a UV based disinfectant does not attain the correct values, major problems may ensue. Both the reach and the values of a UV technology based device can be measured with light meters. In this article we will explain which UV based light meters can be used to detect the presence of UV technology radiation in disinfection devices.
How to measure UV based technology with a radiometer
UV based light cannot be seen with the naked eye. Special meters, such as radiometers, allow one to measure invisible UV based light. Radiometers are devices that measure thermal radiation and thus also UV technology. The main components of the radiometer (figure 1) are the sensor and the display. A UV based sensor consists of a receiver which detects the properties of UV tech and then converts this into a numerical value. This value is shown on the display. The numerical value can be the UV based irradiation or dose. There are two different types of units which express UV based radiation levels.
- Irradiation, in watts per area (W/m2): UV based radiation is present if the power of the radiation can be measured. This power is often described as irradiation and can be used to calculate the UV based dose.
- Dose per surface area (Joule/m2): The UV based dose is the total amount of UV based absorbed by a surface area in a given time. The higher the measured dose, the more effective the UV based radiation is and thus the more active the disinfection process is.
It's important that the correct value be measured. The effectiveness of UV based technology depends on the combination of exposure time, radiation level and distance. This combination ensures that the correct log reduction is achieved – which is to say, how thoroughly a decontamination process reduces the concentration of a contaminant. In order to achieve a reduction of various bacteria or viruses, a specified minimum dose of UV based light must be administered during the disinfection process. Read more about this in ‘What Is Log Reduction and What Is It Used for?’
In order to take the correct measurement, the sensors must be placed near the UV based lamps.
It's important that the correct settings be entered in the radiometer. A radiometer for technology based on UV intended to measure UV at a wavelength of 254 nm (UV based tech) will not be able to properly detect the light from other UV based sources such as LED, far-UV or pulsed-xenon technology. Sources like LED lighting have a wavelength that's not 254 nm. As such, it's vital that the right equipment or settings be selected.
How to measure UV based technology with a dose indicator (dosimeter)
UV based technology dose indicators are used to check whether the correct UV tech dose can be achieved. Dose indicators (also referred to as ‘dosimeters’) are stickers of sorts. They allow you to see whether UV based light reaches where you want it to reach, and thus to check whether the entire product or surface will be disinfected correctly. If you have any concerns about whether a particular area will be reached, for example due to shadows (read this article), you can use these stickers to test. If the disinfection cycle is activated, the material on the dose indicator will be exposed to UV technology radiation.
Depending on the amount of energy to which the indicator is exposed, the colour of the sticker will change. The colour of the sticker can then be analysed. With some brands, a yellow sticker means that no UV based light was measured, while a red sticker means that UV light was measured! In other words, the color of the sticker will change if the sticker has been ‘touched’ by UV based light. This is an quick and easy way to check whether UV based light is reaching all the required places.
A disadvantage of dosimeters is that the stickers may change color because of exposure to other sources of light, e.g. regular sunlight, even when they are not being directly exposed to UV based technology. UV tech dosimeters should therefore be stored in a dark place when not in use.
Choosing the right UV based light meter
Now you may be wondering which type of UV based light meter to choose. A major advantage of radiometers is that they provide precise qualitative measurement results. They measure both irradiation and dose. The measurement results can then be used in a graph for research purposes. UV Smart recommends the use of UV technology radiometers for those who wish to conduct research on the power and effectiveness of UV based radiation.
Dosimeters, on the other hand, can be used for quantitative measurements. They only allow you to check whether a UV based light dose was actually measured. This is extremely useful if, for example, you are using a robot based on UV to disinfect an area, in that you can see at once where the robot can and cannot reach. Even if there are holes in the object to be disinfected, you can check whether the UV based light reaches these holes. Dosimeters are generally accurate and very easy to read. This is why UV Smart recommends using dosimeters when you want to detect the presence of UV based tech easily and quickly.
If you’d like to know more about UV based technology, be sure to read ‘How to Use UV based technology Reliable’.