Sterilization UVC

Properties of UVC rays:

UVC rays have the particularity of destroying microorganisms such as bacteria, viruses, spores and other pathogens. This method has been used for decades in many applications such as sterilization of operating theaters in hospitals, disinfection of laboratories, air conditioning systems, wastewater, etc. These UVC rays are most effective at the wavelength of 253.7 nm. They are absorbed by the RNA and DNA of cells and microbes that neutralize them and result in their inability to duplicate.

Required power of UVC rays:

The UVC tubes produced by the few major manufacturers (Philips, Osram, Sylvania, etc.) emit UVC rays at a wavelength of 254 nm (maximum efficiency level) with an efficiency close to 30%. A 100 W lamp therefore produces only 30 W of UVC ray of this wavelength.

To be neutralized, viruses require an energy (=power in watts * exposure time in seconds) of 7 to 241 Joule / m2 depending on the type of virus. Consequently, to send this energy to the walls and equipment of a room to be decontaminated, the power required will be determined according to the size of the room but also the maximum time desired for the UVC treatment.

In the case, for example of a dental practice of conventional size (4 m by 4 m and height 2.7 m), it is shown that a UVC lamp power of +/- 300 W is necessary to obtain a decontamination at 99.99% after a time of 5 minutes.
Notes: UVC rays are completely stopped by glass walls (windows, doors) and plexiglass

Conditions for good decontamination:

Light intensity decreases with the inverse of the square of the distance. There is therefore an advantage in placing the UVC lamp in a central position. Likewise, walls and objects that receive live UVC light will receive the most decontaminating energy. On the other hand, studies (www.sciencedirect.com) have shown that the rays are reflected to also reach the back side of objects but with less energy. Good reflection will be obtained by manually cleaned walls to remove organic substances. The position of the lamp is also important to reach both low surfaces (floor and under the seat) as well as walls and worktables.

No ozone production:

Ozone is an aggressive gas which attacks the respiratory tract. It is produced by passing air under UVC radiation between 100 and 200 nm. This is why the quality of the tubes used is essential with a wavelength of 254 nm (without ozone).

What is the impact of radiation on equipment and surfaces:

According to several studies, the impact of UVC on plastic surfaces does not show any particular damage only a slight discoloration. Tests with UVC dosimeters placed on walls and equipment are necessary to validate the quality and effectiveness of UVC144-300 lamps. PTS performs these tests for you when installing the lamp.

For marketing questions : Yves Bareel (PTS 0474/96.16.16) => yves.bareel@ptsmachining.be