EcoWater CHC Series, Service And Troubleshooting Manual, Page: 23 / 130

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stabilized (at atmospheric pressure) and the velocity of the water slows down. Submicron particles of
calcium carbonate called colloids are formed and flow with the water. These become thermodynamically
favored incubation sites to grow crystals composed of Ca
2+
and HCO
3
ions versus metal surfaces in the
system. As the molecules agglomerate, they become heavy and sink to the basin/sump floor. At this
point, the resultant calcium scale is removed via the side stream filter or centrifugal separator and
collection system. This device is periodically backwashed to remove entrapped calcium and other
suspended matter.
Corrosion Protection: Corrosion occurs in a system due to several phenomena mentioned earlier in this
report. All waters are corrosive to some degree; however, the level of corrosive tendency will depend
upon its physical and chemical characteristics. The materials that a given water supply will negatively
affect may differ. For example, water that is corrosive to galvanized pipe may not be corrosive to mild
steel. Corrosion inhibitors that protect one material may have no effect on other materials. Biological
growth in a piping system can also cause corrosion by providing an environment in which physical and
chemical interactions can occur. Several types of system level problems can occur if cooling water
systems are left untreated. A major source of corrosion is the addition of the bio-inhibiting chemicals
themselves. This is true especially when “shocking” is required as chemicals lose effectiveness over time
and a chemical alternative is administered. By the time this new chemical, usually bromine or chlorinebased,
is put into service the biological growth in the system has gotten out of control such that a “super
concentration” of biocide is required. These chemicals tend to be very corrosive. A layer of biofouling on
any surface in the condenser water system acts as a haven for aerobic and anaerobic activity, bacteria
formation, scale accumulation and potential corrosion. By eliminating biofouling, the potential for corrosive
activity is greatly diminished. CHC operating parameters and the absence of chemicals allow the pH
level to be elevated in the range of 8.5 to 9.0. At these values both iron and copper are protected from
oxidation corrosion, which cannot operate in an alkaline state. Under these conditions metals are allowed
to establish a thin layer of natural protection, which is not penetrated by system water or dissolved
oxygen.