UVGI technology at a glance

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.