Chlorine Sensors & Transmitters

Chlorine Sensors & Transmitters

Chlorine (and related oxidant) sensors and transmitters are dedicated liquid-analysis instruments for monitoring disinfection residuals in real time. They are applied where systematic disinfection is required and where overdosing must be avoided due to toxicity, material compatibility, or downstream process impacts. Typical measurement targets include free chlorine, total chlorine, chlorine dioxide, free bromine, and ozone - each aligned to specific disinfectant strategies and water chemistries.

These systems commonly use amperometric measurement: the disinfectant diffuses through a membrane to an electrode system where an electrochemical reaction produces a current proportional to concentration. For chlorine dioxide, for example, diffusion through the membrane and reduction at the working electrode form the basis of the signal, and the approach supports operation across a broad pH and temperature range. For free available chlorine, pH dependence is handled by compensation using pH measurement in the flow assembly and transmitter processing.

Key benefits include immediate visibility of residual control, faster response to demand changes, and improved stability of disinfectant dosing loops. Real-time measurement supports tighter compliance margins and reduces chemical consumption by minimizing the “safety cushion” often used with manual verification alone. When integrated correctly, the result is more consistent microbial control with lower risk of disinfection byproduct drivers associated with excessive dosing.

Application fit is disinfectant-specific. Free chlorine is widely used in drinking water, hygienic process water applications, and pools; chlorine dioxide is often selected for its reduced pH dependence and is applied in cooling systems, drinking water, wash water, and desalination contexts; total chlorine can be used as an indicator of residual disinfectants in discharge and reuse; free bromine is common in seawater-related services; and ozone measurement supports pretreatment and disinfection strategies.

Implementation typically pairs the sensor with an appropriate transmitter and installation method - open-channel/basin mounting or flow assemblies - based on hydraulics, maintenance access, and representativeness. Packaged monitoring panels can further standardize installation by consolidating sensor, transmitter, assembly, filtration, and sampling hardware into a compact measuring point, reducing engineering variability and commissioning time.

At Eastern Controls, We are proud to be the exclusive authorized sales and service representative for Endress+Hauser.