What are closed system water circuits?

Closed systems, closed circuits or closed loop water systems are used in almost all commercial, industrial and process environments where they provide heating or cooling to work spaces and manufacturing or process areas.

Closed circuits operate as a “closed loop” or “closed system” meaning that they are sealed and the water inside is not exposed to the atmosphere, meaning a closed loop system contains a fixed volume of water that recirculates and tends to suffer only negligible water losses.

Problems affecting closed loop systems

If closed loop systems or the water used within them are poorly maintained or left untreated it can lead to problems that will affect energy usage, cost, asset performance and reliability. Specifically, these problems include corrosion, fouling, biofouling and scaling to a lesser extent unless there is significant water loss requiring additional make-up water.

• Corrosion
• Fouling
• Biofouling
• Scaling

To combat these problems, closed loop systems and the water within them require suitable treatment.

Successful closed circuit water treatment

Successful management of closed loop systems requires a comprehensive approach to the maintenance and protection of both the system, its components and the water used in them against the detrimental effects of corrosion, fouling, biofouling and scaling.

Integrated Compliance comprehensive approach to the successful management of closed loop water systems involves control of the following issues:

• Appropriate control measures to minimise system corrosion.
• Controlling fouling in the system to reduce blockage, maintain energy transfer efficiencies, and flow rates.
• Controlling biofouling from microbes, pseudomonas bacteria, nitrifying and sulphate reducing bacteria.
• Scaling in closed circuits is generally less of an issue but is problematic where significant make-up volumes are required.

Inhibiting corrosion in closed loop water systems

Corrosion can affect closed water systems even though oxygen levels tend to be lower in such fixed volume water systems. However, it is common in heating systems where fluctuating temperatures can increase rates of corrosion.

Corrosion control is important as if left unchecked it can lead to the degradation of metallic components and increased fouling from corrosion by-products. This will result in lower flow rates, cause blockages, and reduce reliability and life-expectancy.

Chemical corrosion control is achieved by incorporating specialist closed loop water treatment including high performance corrosion inhibitors and oxygen scavengers in to the water treatment programme.

Controlling fouling & microbial slimes in closed circuits

Closed circuit water systems may become fouled from sources such as suspended solids, corrosion by-products, scaling and the build-up of microbial slimes from pseudomonas bacteria, nitrifying and sulphate reducing bacteria.

The accumulation of fouling in the form of sludge and suspended solids may cause blockages, reduce heat transfer efficiencies, and constrict flow rates. It may also cause localised corrosion.

Controlling pseudomonas in chilled & cooling water systems

Pseudomonas bacteria may cause significant biofouling issues in chilled and cooling water systems, particularly those that are poorly maintained or untreated. As Pseudomonas bacteria proliferates throughout closed-circuit water systems it can accumulate to build thick microbial slimes which both contaminate the water and reduce heat transfer efficiencies (cooling) and increase operating costs.

Our expert water treatment engineers use techniques specifically designed to deal with Pseudomonas and other slime forming bacteria in closed systems. They act to disperse and then flush the unwanted microbial materials from the water systems to restore water quality and cooling performance.