ARE UV-C RAYS ?
The small part of electromagnetic spectrum having wave lengths included
between 100 and 400 nm (thousandths of micron) is defined as space of
the ultraviolet irradiation. The UV-C are part of the subspace characterized
by the wave lengths included between 100 and 280 nm. Electromagnetic
waves with different wave length and width induce interactions with
the matter of different nature, the UV-C irradiation with = 254 nm is
particularly interesting thanks to its marked germicidal power.
DO THEY WORK ?
The high germicidal power of this wave length must be sought in DNA
and in the link of its fundamental components (nucleotides). DNA is
a macromolecule present in all living organisms in which all information
necessary for life and reproduction reside. The alteration, induced
by the UV-C irradiation, of some chemical links present among nucleotides
is able to change the information contained and conveyed by DNA, these
alterations prevent its normal activity and this irreversibly leads
to the cellular death.
MUCH DO THEY WORK ?
For being effective in the sterilization, an electromagnetic wave, besides
being of a certain kind ( = 254 nm) it must possess also a minimum value
of intensity to be able to ensure a minimum dose to water. The parameters
which mostly influence the calculation of the dose are: P=power of the
UV-C lamp, T=time of exposure (which depends on the flow-rate and on
the dimensional characteristics of the unit), exp(-kx)=transmission
factor (depending on the distance of the UV lamp and on the transparency
of water), CT=temperature coefficient of water. A UV sterilizer, if
correctly sized, is able to give water a dose sufficient for reducing
almost all the commonest microorganisms present in water.
ARE THEY PRODUCED ?
In nature the UV-C rays are part of the secondary cosmic irradiation
which, interacting with the high strata of the terrestrial atmosphere,
generates ozone and with a lower energy, it reaches ground as tanning
UV(A+B) irradiation. Artificially UV-C rays are produced with the help
of special fluorescent lamps containing mercury fumes, these lamps are
made of a very pure quartz (>99.99% SiO2) transparent to the UV-C
light which they emit in an almost monochromatic form (>95% of =
ARE THEY CONVENIENT ?
Among the several advantages offered by this kind of technology we mention: