The importance of keeping cooling tower water
in proper chemical balance is becoming clearer. Cooling tower treatment
control systems can limit scale formation to improve efficiency, limit
corrosion to increase the service life of the cooling water
system, and maintain a residual halogen level to reduce liability
associated with biological growth, particularly Legionellae.
The
use of automatic control equipment rather than manual measurement and
adjustment has increased dramatically in the past several years,
motivated in part by the loss of on-site personnel to perform the task,
in part by the safety aspects of chemical handling, and in part by
efforts to conserve water.
Environmental concerns have also driven the increased use of pH and oxidation-reduction potential (ORP) controllers in cooling water systems. After the use of heavy metals
was banned, the simple treatment method to control chromate passivation
could not be used to protect the cooling systems. The newer,
alternative methods can be more sensitive to pH fluctuations. For
example, alkaline orthophosphate treatments can result in corrosion if
the pH drops, and in calcium phosphate scaling if the pH rises. The use of automatic pH control minimizes this problem.
Similarly,
the combination of pH control and ORP control can maintain chlorine
and/or bromine residuals at the levels required to inhibit survival of
bacterium and the biofilm that supports them. Maintaining a constant
low-level halogen residual also minimizes the amount of chemical that is
discharged into the environment.
Installation of automatic control equipment is also a great way for water treatment chemical providers to differentiate themselves from the competition by increasing their level of service to the owner of the cooling towers.
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