Re-Circulated Water Quality Guidelines - BAC VX Series Operation & Maintenance Manual

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Table Of Contents

Table of Contents

In cooling towers, cooling is accomplished by evaporation of a portion

of the process water as it flows through the tower. As this water

evaporates, the impurities originally present remain in the recirculating

water. The concentration of the dissolved solids increases rapidly and

can reach unacceptable levels. In addition, airborne impurities are

often introduced into the recirculating water, intensifying the problem.

If these impurities and contaminates are not effectively controlled, they

can cause scaling, corrosion, and sludge accumulations which reduce

heat transfer efficiency and increase system operating costs.

The degree to which dissolved solids and other impurities build up in

the recirculating water may be defined as the cycles of concentration.

Specifically, cycles of concentration is the ratio of dissolved solids

(for example: TDS, chlorides, sulfates) in the recirculating water to

dissolved solids in the make-up water.

For optimal heat transfer efficiency and maximum equipment life, the cycles

of concentration should be controlled such that the recirculating water is

maintained within the guidelines listed below: