Technical
which the pH value does not have a corrosive effect on any components is reduced .
HARD TALK Water hardness is defined by the content of alkaline earth metal ions . On the one hand , there is carbonate hardness , which is also called temporary hardness , and on the other there is permanent hardness . Non-permanent hydrogen carbonates , which are dissolved in water when a circuit is filled , precipitate into carbon dioxide and carbonates locate at the warm sections of a circuit and can cause significant efficiency losses .
The conductivity of water is determined by the amount of anions and cations dissolved in the water including minerals such as magnesium , calcium and hydrogen carbonate , as well as salts and dissolved metal ions . The more particles present , the higher the conductivity and thus the susceptibility to electrolytic corrosion . In chilled water systems lime always precipitates at the warmest point with the lowest flow velocity , and in most cases this is the air to water heat exchanger . As such , there is a risk that it will become clogged , which can also lead to stress cracks .
When checking water conditions , special attention should be paid to salts . Dissolved salts in particular are critical for the chilled water circuit , as they are very reactive and cause precipitation and corrosion . Chloride is the salt of hydrochloric acid and is the most stable parameter in the loop system . Primarily , it serves as a chemical catalyst that also accelerates corrosion processes .
TIME FOR ACTION In addition to mandatory leak and function tests , a comprehensive cooling system maintenance strategy should include preventive corrosion protection for air cooled or air exposed heat exchangers . Even seemingly simple measures can help and to permanently improve protection , so it is advisable to remove coarse dirt such as leaves , pollen and dust from heat exchanger surfaces at regular intervals . The coating must then be thoroughly checked for contamination and damage . Finally , when using a cleaning agent , make sure that it is compatible with the coating – information about this can be provided by the system manufacturer .
ABOUT THE AUTHOR Tobias Wolf has a degree in Mechanical Engineering and a Double Masters in Energy Technologies ( ENTECH ). Tobias joined Stulz in 2017 with a focus on chillers and precision air conditioners for data centers , telecommunications and industry . With 14 years experience in refrigeration , air conditioning and environmental technology , as well as energy efficiency and building services engineering , he is a knowledgeable expert in this field . RACA
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RACA Journal I February 2022 www . hvacronline . co . za