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W W W . B A L T I M O R E A I R C O I L . C O M . A U
Biological Control
1. The warm, oxygen and nutrient rich environment inside
evaporative cooling equipment provides an ideal environment
conducive to the growth of algae, slime, and other micro-
organisms. Uncontrolled, this can reduce heat transfer, promote
corrosion and the growth of potentially harmful organisms such
as Legionella. To avoid biological contamination and minimise
the risk of Legionella, initiate the biocide treatment program at
start-up and continue on a regular basis thereafter in accordance
with the treatment supplier's instructions.
2. Bleed/blowdown or chemical treatment used for corrosion and
scale control alone is not adequate for control of biological
contamination.
3. Introduce solid or granular biocides through a chemical "pot"
feeder installed in parallel with the system circulating pump.
Diluted liquid biocides may be added directly to the cold water
basin.
4. If ozone water treatment is used, at no point should
concentrations exceed 0.5 ppm.
5. Initial Start-up & Start-up following a Shutdown Period.
• To minimise the risk of biological contamination
during a shut-down period of three days or more, it
is recommended that the entire system (evaporative
cooling equipment, system piping, heat exchangers,
etc.) be drained.
• To resume operation of a drained system and at initial
start-up, clean all debris from the cold water basin and
fill the system with fresh water. Then, execute one of the
following biocide treatment programs while operating the
circulating pump and prior to operating the unit fans.
• Resume treatment with the biocide that was used prior
to shut-down. Then run the pump only while maintaining
the maximum recommended biocide residual for a
sufficient duration (residual and time will vary with
the biocide) as recommended by the water treatment
supplier. Start the fan only after this treatment period is
completed.
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