UVC TREATMENT
THE PROPERTIES OF UVC
UVC rays at 253.7 nm are germicidal
Germicide smeans destruction of germs or Micro-organisms
Viruses – Yeasts – Bacteria – Protozoa – Worms – Algae – Molds
UVC decontamination merely “kills” or “inactivates” germs without generating chemical effluents that are harmful to the environment, hence its undeniable advantage
UVC rays at 185 nm produce
deodorizing gas
They have the property of breaking down the air and promoting the formation of an OZONE (O3) gas. Ozone is a very oxidizing gas and this effect, combined with UVC radiation at 254nm, allows it to be used in deodorization processes.
UVC ultraviolet radiation (very energetic) produces molecular photochemical reactions.
In its reaction with microorganisms, mainly by absorption of UV photons between 250 and 270 nanometers, the DNA or RNA molecular dissociation that takes place damages the membrane of cells and the nucleus, which causes local mutations and thus prevents reproduction of microorganisms which are therefore inactivated and finaly annihilated. This is why UV radiation is used in decontamination processes which consist in the destruction of germs, in particular those known as pathogens.
Disinfection – Sterilization
In general, the term disinfection is used when the level of microorganisms remaining is lower than the one which can trigger disease. The term sterilization is used when all living microorganisms are killed.
Lamp efficiency for germicidal applications
The germicidal efficiency of UVC Radiation is between 180 and 320 nm with an optimum at 265 nm.. Low pressure mercury germicidal lamps are uniquely designed to produce the highest amounts of UVC radiation. These radiations are very close to the top of the germicidal efficiency curve which is located at 265nm, the wavelength most lethal to microorganisms (see curve).
This source is the most efficient for germicidal applications, as approximately 95% of the energy emitted by a low pressure mercury arc is at 253.7 nm.
UVC SOURCES
GERMICIDAL LAMPS
The germicidal effect by UVC radiation, studied for more than 70 years, has benefited from research into different processes producing radiation at 253.7 nm. So-called “mercury” tubes, whose operation is identical to “fluorescent” tubes, are used by ERIES® for this process.
These lamps can be of several types, mainly:
– Low pressure of mercury
– Medium pressure of mercury
– High pressure of mercury.
They differ in the yield of UVC radiated energy compared to the total electrical power:
– 30% for low pressure lamps
– 10 to 20% medium pressure lamps
– 5 to 6% for high pressure lamps.
Lamps (commonly called tubes)
The lamp is composed of a quartz tube and an electrode at each end. After the ignition of the electric arc between the 2 electrodes, the “gas”, which is in fact mercury vapor, is ionized by the passage of current.
The emission spectrum of ionized mercury is located at 253.7 nm, very close to the maximum absorption peak by microorganisms, between 250 and 270 nm.
GERMICIDAL QUARTZ LAMPS
The tube forming these lamps is made of quartz.
There are several types whose quality is judged here in relation to their ability to filter or pass certain wavelengths. One of these qualities of quartz is to filter radiation below 254 nm thus preventing the passage of 185 nm. These lamps are called Low-Ozone and are only considered as germicides. Another quality of quartz also allows the 185 nm to pass. These lamps are called High-Ozone and are considered as “germicides” plus an “oxidizing effect” (used for the treatment of odors, in particular).
Standard Lamps
The type of quartz used to make the germicidal lamp body determines the wavelength emission of UV energy. “Low Ozone” lamps transmit up to 90% of their energy at 254nm. In ozone-generating lamps its special quartz is clear fused to UVC and allows the transmission of energy at 185nm and 254nm.
High Output Lamps – HO
HO (High Power) lamps offer system designers the unique opportunity to reduce the number of lamps required without compromising efficiency. This has the additional potential benefits of a reduced system footprint, improved efficiency and / or increased system capacity.
HO lamps are available in the same configurations as Standard lamps. Custom lengths and can also be tailored to specific customer requirements.
Amalgam Lamps
Our manufacturer Light Sources also provides a high quality range. This range is the broadest of spotlight and amalgam pellet lamps in the industry today. Amalgam low pressure lamps operate with equal efficiency both horizontally and vertically. Amalgam lamps provide up to three times the UVC radiation of standard lamps of the same length.
