TECHNOLOGY
The UV-C-Technologie - in brief
Ultraviolet rays make up part of the natural sunlight’s spectrum. Around the wavelength range of 253, 7 nm they have a bactericidal effect on bacteria, viruses, yeasts and mildew. By the UVC disinfection of the air and the surfaces all micro-organisms effectively get inactivated.
By the innovative technology of UV disinfection there are deriving direct advantages for the operator:
The technology of UVC disinfection has no chemistry, no toxic compound and no formation of resistance. Undesirable micro-organisms get inactivated within seconds, whilst the product characteristics persist. In addition the application of UV disinfection meets the high requirements of the consumer protection and the VDI 6022 as well as the HACCP concepts. Not least the application of UVC disinfection has a positive effect on the IFS certifications.
The beginning
For a long time the sun light is attributed the characteristics to contain a spread of infections. In 1878 the English scientists Downes and Blunt discovered, that the multiplying of micro-organisms significantly gets reduced when exposed to sunlight. At that time the course of this process could not be cleared yet.
Later researches showed that this effect starts from the invisible part of the solar radiation below the wavelength range of 320 nm. From the moment of this discovery it was possible to originate an artificial radiation source for the generation of bactericidal radiation.
The kind of radiation, which causes an inactivation of bacteria, nowadays is well-known as ultraviolet radiation.
The ultraviolet radiation
Ultraviolet radiation, as well as visible light or radio waves is an electromagnetic radiation and cannot be perceived by a human eye. By definition it contains the spectral range of 100 up to 380 nm and thus directly joins the blue, visible part of the light.
The ultraviolet spectrum includes wavelengths up to 380 nm and is subdivided as follows:
| UV-A | 380-315 nm "blacklight" |
| UV-B | 315-280 nm responsible for sunburn |
| UV-C | 280-200 nm disinfection effect |
| UV-C-VUV | 200-100 nm ozone formation |
Ultraviolet radiation is present in the sunlight. Because of the absorption in Earth’s atmosphere (particularly in the ozone layer) radiations reach the surface of the earth with a wavelength range beyond 300 nm – particularly UV-A and a lower part of UV-B.
| UV-A rays tan the skin and accelerate skin aging. | Within the ultraviolet range we distinguish three types of rays. The UV-A rays reside around a wavelength range of 315 to 380 nanometres. They are the most long wave UV-rays and responsible for the tanning of the skin. |
UV-B rays can damage the skin. |
The UV-B light ranges in a wavelength range of 280 to 315 nanometres. It is higher-energy than the UV-A light. The UV-B radiation penetrates the areas of the epidermis and there turns into energy. That is the reason for the origin of sunburn. |
| UV-C rays are selected from the ozone layer and offer a high disinfection effect. | The UV-C light with 100 to 280 nanometres is the shortest wavelength range of the ultraviolet light. With intact ozone layer however this range of ultraviolet light gets filtered from the solar ray spectrum before impinging upon earth’s surface. |
As contrasted to UV-B radiation, which particularly deeply penetrates the epidermis, a causal relation of dermal cancer owing to intensive UV-C radiation could not yet be scientifically proven.
The principle of operation
The extreme high-energy UVC radiation prompts a photochemical reaction. The wavelengths with 253, 7 nm get absorbed by the cell nucleic acids and, depending on the radiation dosage, lead to a killing, resp. impairment of germs and fungal spores. Hence the UVC radiation sees use in the targeted impairment or killing of micro-organisms (like e.g. germs, viruses, yeasts and mildew).
The dose principle
The dose principle refers to the fundamental influence of the factors time and performance. The product of irradiation time and irradiation intensity is quoted in MW*s/cm².
UVC dose (mWs/cm²) = intensity (mW/cm²) x time (s)
While simply structured micro-organisms show a high sensitivity to UVC radiation, i.e. they easily may be deactivated with a minor dose, significantly higher energies are necessary in order to kill mildew and spores. The efficiency of UVC with the inactivation of micro-organisms therefore always is in direct relation to the applied dose.
That way sterilisation rates of up to 99, 99 % may be economically realised, depending on the requirement. The exact UVC dose that results in an inactivation of the micro-organisms, type-specifically differs. Whilst the majority of germs and viruses can be inactivated with relatively low doses, yeast, mildew and spores require a multiplicatively higher dose.
The disinfection technology
Several influencing factors such as sojourn time, air humidity, turbidity and temperature with the construction of UVC units must be strictly calculated and considered. For this purpose we use our year-long experience and the technology, we continuously developed.
The main spectrum of the STERILSSYSTEMS UVC lamp is on the range of 254 or of 185 nm. Beneath 240 nm of wavelength the ultraviolet light generates ozone from oxygen.
Especially for the disinfection in the food sector only those emitters are applied that don’t create ozone. An ozone formation during the disinfection process gets prevented with STERILSYSTEMS UVC germicidal lamps by use of special materials.
An important advantage of the physical UVC disinfection is that it cannot cause any resistance. The UV disinfection even works out, when germs already attained a resistance against conventional disinfection methods like alcohol, antibiotics etc. …
The UVC disinfection works out with all kind of micro-organisms, no matter whether it concerned the frequently arising E. coli bacteria, SARS, legionella or mould. A sufficient UV dose, many years of application know-how and the necessary device technology are the basis for the desired success.
The number of scientific proofs straight continued to increase in the last years.
Thus e.g. in the drinking water ordinance UVC water disinfection reactors are listed as one of the methods of disinfection. UV water disinfection units get certified to DVGW and Austrian Standard. For air handling systems the VDI 6022 applies and regulates the usage of UVC radiation for safe air disinfection.
In a sufficient dose UVC rays cause skin redness (erythema) and ophthalmitis, well-known also as arc eye. That’s why the limit value must not be exceeded.
UVC radiation with 254 nm may be shielded by normal window glass, transparent plastics like Makrolone® and practically all opaque materials. For further information concerning UV filters please consider the norm „EN 170 - Personal eye protection“. Quartz glass is permeable for UVC radiation and must not be applied for personal protection.
The odour removal
We face aggressive odours with high potency active oxygen – ozone O3.
Ozone is a natural, gaseous molecule, consisting of three oxygen atoms, and frequently occurs in nature.
In the stratosphere it protects our planet from ultraviolet solar radiation as ozone layer. It forms in minor concentrations with thunderbolts. The fact, that ozone is frequently related to air pollution, bestowed a rather hostile image on this gas - wrongfully! If applied in the right way it is an effective and non-polluting alternative to chemical processes.
Ozone consists of three oxygen atoms. Under near-Earth normal conditions the gas is instable and thus highly reactive. The ozone molecule quickly reacts with a wide range of organic and inorganic compounds. During this process of oxidation the ozone generally gets completely consumed and decomposes to oxygen.