COC from Conductivity

Field method to monitor cycles, since most dissolved solids contribute to conductivity. A conductivity controller opens the blowdown valve when tower conductivity exceeds the setpoint. Limitation: conductivity does not detect species that precipitate as scale.

$$\text{COC}\approx \frac{\text{Tower Conductivity}}{\text{Makeup Conductivity}}$$

Variables

Symbol	Meaning	Unit
Tower Conductivity	Conductivity of tower water	microsiemens/cm
Makeup Conductivity	Conductivity of makeup water	microsiemens/cm

Worked example

Target tower conductivity = makeup x COC = 400 x 5 = 2,000 microsiemens/cm.

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Part of The Blueprint of Water