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.