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UVGI technology at a glance

Articles UV-C
22.08.2024
UVGI technology at a glance - Light Progress
latest update August 22, 2024
Ultra Violet Germicidal Irradiation (UVGI)

Ultraviolet is that part of electromagnetic radiation bounded by the lower wavelength extreme of the visible spectrum and the upper end of the X-ray radiation band. The spectral range of ultraviolet radiation is, by definition between 100 and 400nm (1nm=10-9m) and is invisible to human eyes.
UV spectrum is subdivided into three bands:
  • UV-A (long-wave)from 315 to 400 nm
  • UV-B (medium-wave)from 280 to 315 nm
  • UV-C (short-wave)from 100 to 280 nm
The portion of the UV spectrum (the “germicidal” region) that is important for the disinfection is the range that is absorbed by DNA (RNA in some viruses).  This “germicidal range” is approximately 200 – 300 nm, with a peak of germicidal effectiveness at about 265 nm.  The absorption of a UV photon by the DNA chain of dangerous microrganisms causes a distruption of a link and consequently an inhibition of DNA replication.
  • 265,0 nm peak of germicidal effect
  • 253,7 nm common UV-C bulbs
  • 280,0 nm length used by LED (NEW!!)
There are different types of lamps:
The discharge lamp is a type of bulb based on the light emission by luminescence from an ionized gas. The ionization of the gas is obtained by means of a potential difference, which migrates the free electrons and positive ions to the different ends of the lamp (where there are electrodes).
  • Low pressure UV lamps. These offer high efficiency (approximately 35% UV-C) but low power, typically 1 W/cm (power per unit of arc length). They produce ultraviolet radiation at 254 nm.
  • UV amalgam lamps. A high power version of low pressure lamps. They operate at higher temperatures and have a lifetime of up to 16000 hours. Their efficiency is slightly lower than that of traditional low-pressure lamps (approximately 33% UV-C) and the power density is about 2-3 W/cm.
  • Medium pressure UV lamps. These lamps have a spectrum with a pronounced peak and high radiation production but a low efficiency of 15% or less of UV-C. Typical power density is 30 W/cm³ or larger. They produce polychromatic light from 200 nm up to visible and infrared light. Depending on the quartz glass used for the lamp body, low pressure and amalgam lamps emit light at 254 nm and 185 nm (by oxidation). Light at 185 nm is used to produce ozone.
All these UV-C sources are exhausted both by the "discharge" of the gas contained within the bulb and by the progressive loss of transparency of the glass that forms them, in which walls are deposited electrons.

Light Progress lamps are low-pressure, high-output mercury vapor UV lamps, optimized to produce monochromatic radiation at a wavelength of 254 nanometers.

Primarily used for disinfection and sterilization, these lamps utilize short-wavelength ultraviolet radiation to eliminate pathogenic microorganisms such as viruses, bacteria, and spores. They are available in various sizes and shapes to suit a wide range of applications.

Advantages of UV-C Lamps

  • Effectiveness: UV-C lamps can eliminate up to 99.9% of pathogenic microorganisms, including those resistant to chemical disinfectants.
  • Speed: Disinfection occurs in seconds or minutes, depending on the lamp’s power and the distance from the object or surface to be treated.
  • Sustainability: Since they do not require the use of chemicals, UV-C lamps represent an eco-friendly and safer solution for the environment.

For a UV-C lamp to be effective, it is essential that the materials through which the radiation passes are highly transparent at the specific wavelength (253.7 nm). Common glass, for example, blocks most UV-C radiation, making it unsuitable for the casing of such lamps. Quartz, on the other hand, is the most commonly used material as it offers optimal transparency to UV-C rays, ensuring maximum disinfection effectiveness.

We have prepared a separate article (uvgi-technology-at-a-glance-part-ii) covering topics of great interest to our clients who intend to integrate and use UVC technology, such as resistance to plastic materials, transparency of certain materials, the presence of mercury, and more.

UV-C LEDs
The most innovative source of ultraviolet rays is UV-C Light Emitting Diodes (LEDs).
These microscopic UV light sources can offer revolutionary features in terms of portability, power, and applicability.
The R&D department of Light Progress is committed to developing new products that can maximize the advantages of this technology.

However, the following are the main limitations currently hindering the widespread adoption of products using UVC LED technology:

  • Emission Power: UVC LEDs tend to have lower emission power, making them less effective for large-scale applications or in environments that require high UVC intensities for rapid disinfection.
  • Cost: UVC LEDs are currently more expensive to produce than mercury UVC lamps, which can be a barrier to their widespread adoption.

F.A.Q.

Ultraviolet rays are electromagnetic waves which are part of light. Electromagnetic waves are divided into three main wavelength bands, expressed in nanometers, nm: Ultraviolet rays (UV) 100-400 nm Visible rays (light) 400-700 nm Infrared rays (IR) 700-800,000 nm UV rays are in turn identified in three bands:

  • UV-A (315-400 nm) with tanning properties;
  • UV-B (280-315 nm) con proprietà terapeutiche e di sintesi della vitamina "D";
  • UV-C (100-280 nm) with germicidal properties.

UV-C rays (100-280 nm) have a strong germicidal effect and reach their maximum efficacy at the 265 nm wavelength. The germicidal effect of UV-C radiation covers bacteria, viruses, spores, fungi, moulds and mites; this is mainly due to the destructive effect of the UV-C rays on their DNA, which damage their reproductive system and prevent them from replicating.

Bacteria, Viruses, Spores, Fungi, Mould, and Mites are all sensitive to, and can therefore be eliminated with, UV-C light. Mircrobes cannot acquire resistance to UV-C light, unlike that which occurs using chemical disinfectants and antibiotics. UV rays are ecological. Polluting the environment is inevitable using normal disinfectants. Directly inhaling the vapours, or swallowing food products contaminated by any contact with said chemical disinfectants, can also give rise to a number of serious risks. In cases where chemical disinfectants cannot be eliminated (food, pharmaceutical, healthcare industries, etc.), using ultraviolet rays for disinfection allows a reduction in their use, with considerable economic savings and greater care for the environment, while maintaining and almost always improving the level of disinfection. UV-C light devices can be installed in environments and on machinery and be programmed to maintain the same level of disinfection day and night, guaranteeing ideal hygiene conditions, without highs and lows. On the contrary, chemical disinfectants are effective only during their actual use. Using LIGHT PROGRESS equipped luminaires, operating costs are negligible; it could be said that “LIGHT PROGRESS” UV-C systems do not require maintenance except for the normal replacement of the lamps. The cost/benefit ratio is considered excellent; the devices are both powerful and long-lasting. Hence the elimination of germs using UV-C technology is low-cost and highly effective compared to (or in combination with) other systems.

UV-C really does work when applied correctly and with the necessary precautions. The difference between a quality project and an unsuccessful application is in-depth knowledge and experience gained over time. Since 1987, Light Progress has been carrying out successful projects all over the world and has acquired a clientele of major companies in all sectors that require verified hygienic conditions to produce quality products and services.