8 Considerations When Choosing A Biocide To Be Used In Closed Circuit Systems
A biocide is a chemical solution formulated to effectively limit the growth
of microbial species. To minimize any risks that are related to microbial growth
like heat loss, under deposit corrosion and health hazards, it is important to
establish the correct biocidal treatment strategy.
In our last blog, we discussed the top factors to consider when selecting the
best oxidizing biocides. In this blog
we focus on selecting the right closed circuit biocides.
There are many elements that can adversely impact the microbial levels in
closed-circuit systems. These should also be considered.
1. Cleaning before the commission
It is essential to ensure the purity of new systems and the use of biocide
during the pre-commission cleaning (as as per BSRIA the BG29/2020) is
done.
2. Concentration
It is essential to ensure that the closed-circuit biocide or inhibitor are in
the system in the proper concentration. This can be verified with pressure
testing. This could also be conducted on a regular basis.
3. Formulation based on Nitrite
A cost-effective formula that is neutral and nitrite-based, which easily
passesivates and is well-suited to multi-metal systems containing aluminum, such
as Polyhib LC might be suitable. There are other products available. Contact our
technical department to determine the most suitable product. The right biocide
should be used if Polyhib-LC is used to keep the system once it has been
filled.
4. Closed system chemistry testing, and monitoring of microbiological
health
Closed system chemistry testing is an essential part of any maintenance
program. Monitoring of microbiological activity in the system is also an
important role. Dosing a dose of shock Biocide chemicals as a response to high
bacterial numbers is essential to ensure that control of microbial numbers is
maintained.
5. Tests for sensitivity to biocide
It is possible for resistance to develop over time and it might be necessary
to modify the biocide dosage regimen. It may be necessary that certain systems
undergo a biocide-sensitivity analysis in order to determine the most effective
biocide. Our on-site laboratory is able to accept samples for analysis of the
biocide's sensitivity. We then can conduct the analysis on behalf of our
customers. For more information on pricing and details, please contact
us.
6. Biodispersants
In the event of high levels of bacterial growth and a build-up of biofilm is
present, dosing an effective biocide with a biodispersant compatible such as
BV167 and BV1455 could be necessary. While removing biofilm off metal surfaces,
it's crucial to determine the source of this biofilm. Filters and strainers that
are scattered throughout a system must be cleaned and checked regularly. If the
system has small bore pipework and no strainers or filters blocked, it is
possible to have blockages. Biodispersants are not suitable for all
systems.
7. Temperature
A biocide is typically not needed if the temperature of the fully circulated
LPHW (Low Pressure hot water) systems remains constant at or above 60°C. If such
a system is used during the winter months it is suggested that a biocide be
added and allowed to circulate throughout the system prior to the time it is
switched off. BSRIA BG 50 recommends a minimum time for circulation in cooling
and heating circuits of an hour each day, even for seasonal utilized
systems.
8. Glycol
In a chiller that is containing glycol, the levels must be maintained at an
ideal concentration of 25% to avoid the growth of bacterial. The glycol
concentration is biostatic. it blocks the growth of bacteria. In the lower
range, glycol can act as a nutrient to bacteria.
It is vital to keep in mind that all biocidal products must be handled with care, and workers must wear appropriate personal protection equipment (PPE) always. The Safety Data Sheet (SDS) of every biocide should be read prior to using.
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