What is Closed System Testing?
Closed System Testing refers to testing water in a controlled environment. In closed-system testing, there are microbiological, physical and chemical analyses.
Tests include a physical inspection of the water, measuring pH levels, and analysing the concentrations of minerals such as copper, iron, calcium, magnesium, zinc, phosphates, silicates, potassium, aluminium and sodium. Echo Square specialises in closed-system water testing to support BSRIA BG 50/2013 standards.
Here are several reasons why
closed system testing is important:
Environment Control
Closed water testing allows researchers to create and maintain specific environmental conditions, such as temperature, pH levels, water chemistry, and nutrient concentrations.
Replicability
Closed water testing facilitates the replication of experiments by using standardized protocols and maintaining consistent conditions.
Interference
Closed systems minimize the influence of external factors on experimental outcomes. They isolate the aquatic environment from natural disturbances.
Time Efficiency
Closed water testing can accelerate research progress by enabling faster data collection and analysis.
Cost-Effectiveness
Closed systems can be more cost-effective than conducting field studies. They eliminate the need for extensive fieldwork, such as travel expenses, logistical challenges, and potential risks.
Microbiological Analysis
Microbiological Analysis tests for bacteria most commonly found in closed systems. If left to proliferate, this can cause serious problems.
TVC/Aerobic colony count
Nitrite Reducing Bacteria
Pseudomonas Bacteria
Sulphite Reducing Bacteria
Physical & Chemical Analysis
Evaluating water composition in enclosed systems entails assessing the concentrations of different components, such as metals and other substances, in the water.
Alkalinity as CaCO3
Aluminium (Dissolved)
Boron (Dissolved)
Ammoniacal nitrogen
Calcium (Dissolved)
Conductivity
Plus, much more. Other Tests can be carried out as required.
New Commissions & Water Quality Considerations
During the initial heating or cooling system charging, the tanks are typically filled with water sourced directly from the mains water supply. Consequently, the closed system will inherit the bacterial and mineral content present in the main water.
Regional variations and the specific water source influence the levels of bacteria and minerals in the closed system. Notably, the mineral composition can differ across geographical locations and water extraction points.
Furthermore, it is important to note that the expected bacterial levels in mains water can range from 10 to 100 cfu (colony-forming units) per millilitre of water.
Testing for Bacteria in Closed-systems
Various types of bacteria can be found in mains water. Although Enterobacter, Klebsiella, and Citrobacter may exist, their survival and growth within a closed system are highly unlikely.
Nevertheless, as these bacteria perish, they can serve as a nutrient source for other bacterial varieties.
Additional bacterial species that can pose problems in closed heating and cooling systems include Pseudomonas, Flavobacterium, Acinetobacter, and Aeromonas.
These bacteria generally do not proliferate to levels that cause issues in a drinking water supply.
However, in a closed system, they can rapidly produce slime and initiate the formation of biofilm on internal surfaces such as pipework, pumps, and heat exchangers.
Moreover, mains water can also contain iron, sulphite-oxidising bacteria, and sulphite-reducing bacteria.
Iron bacteria thrive on ferrous substances and can contribute to corrosion.
The presence of red, orange, or yellow-coloured water often indicates the presence of iron bacteria.
If a black slime is observed within the system, it suggests the presence of sulphite-oxidising bacteria. If an unpleasant odour accompanies the slime, the issue may involve sulphite-reducing bacteria.
This type of bacteria is highly corrosive and can cause significant damage.
Biofilm Problems
When a newly commissioned closed system is put into service, one of the initial types of bacteria to establish itself is typically the slime or biofilm-forming bacteria.
These bacteria have the capability to form layers of biofilm on surfaces, creating a conducive environment for other bacteria to grow as well.
As the bacterial population accumulates, it inevitably begins to impact the thermal efficiency and overall operation of the closed heating or cooling system.
Bacterial layers act as insulation, thereby limiting heat transfer efficiency and affecting the system’s hydrology.
If the biofilm grows unrestricted, the oxygen levels within the system gradually diminish.
Consequently, this creates an environment suitable for the growth of anaerobic bacteria, such as sulphite-reducing bacteria (SRB), which do not require oxygen to thrive.
In cases where water levels in the closed system need periodic replenishment from an open header tank, the bacterial count can be even higher.
This is attributed to the specific storage conditions of the water.
If bacteria are not adequately addressed through the use of specialized closed-system water treatment chemicals known as biocides, the entire system may eventually fail. At best, its reliability and thermal effectiveness will be compromised.
Need help with Closed System Testing?
Echo Square are qualified in BSRIA closed system testing in water tanks. If you need support or advice with this particular service, then please do get in touch. Our services are based throughout the United Kingdom.
