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used to be very frequent before the Directive 3523), there are still doubts
whether the drift velocity caused by the fan of the air conditioning is enough
to carry the water aerosol, go through the air filter, coil, fan, ducts and reach
the environment where people is with still the possibility of contamination.
It may be probable, but it is quite unlikely to occur.
Even today, many companies in Brazil still request analysis studies
of
Legionella
for these trays. This can be done and they can even find the
bacteria there, but this is not the most recommended place.
There is a place in the air conditioning system which is considered as
having the greatest potential for proliferation and diffusion of the bacteria:
the cooling tower of the system of water condensation, which is quite used
in commercial buildings, shopping centers, hospitals and medium to large
sized systems all over the world.
In this place, the microorganism finds favorable conditions to grow as
well as a large dispersion of water steam of the evaporation process caused
in this equipment which is considered a heat exchanger.
It has to be clear that the cooling towers are located outside the internal
environments of the buildings, generally in the penthouses of the buildings
or, sometimes, in the ground floor. It means that water circulating in the
system, as well as that evaporated, is not released in the interior of the
building.
The care that has to be taken with these devices is to keep them away
from the circulation of people and 10 meters far, at least, from the outside
air intake of the HVAC system of the building, according to the NBR 16,401
of ABNT – Brazilian Association of Technical Standards.
