Conductivity controller limitation

Definition

The blind spot in which a conductivity controller cannot detect dissolved species that precipitate out as scale, so it holds setpoint while true scaling-ion concentration drifts away.

When calcium carbonate precipitates, its contribution to conductivity disappears, but the controller keeps making up the shortfall as if nothing changed. The result is that conductivity reports concentrating water while scale quietly leaves the mass balance on surfaces. This is the what changes form question of the mass balance, and it is why a tracer comparison is needed.

Related concepts

Solubility limit · Tracer ion comparison · Conductivity as concentration surrogate

---

Part of The Blueprint of Water · 📏 measurement