Water quality monitoring systems for cooling water treatment industry - Water and Wastewater - Water Treatment

A number of treatment products are often added to prevent corrosion, scaling and fouling. Coating of sensors and other effects of these products must be taken into account when selecting analyzers. Discharge monitoring needs special attention because zero measurements must be reliable over time with little maintenance.

Chlorine, Ozone, ClO2

Two different technologies are available for monitoring free chlorine, ozone, chlorine dioxide or monochloramine. The choice of the technology depends on water quality and treatment methods:

  • Amperometric three electrode system TRIDES: Seawater  or common city water. Treatment with free chlorine, chlorine dioxide or ozone. pH below 8.5. No anticorrosion additives. Amperometric systems have lower cost of ownership (no reagents). Under unknown conditions, however, it is safer to use a photometer.
  • Process photometers CODES: Work under the same conditions as the amperometric system. In addition they can be used also for monochloramine and total residual chlorine. No limit for pH levels. They also work well in the presence of anticorrosion additives. Biofouling can be powerfully reduced with the optional Cleaning Module.

A high precision portable photometer is needed for calibration in any case: CHEMATEST portable photometer


Conductivity in power cycles is measured directly (total or specific conductivity) and/or after a cation column (acid or cation conductivity). Additional, a third measurement after sample reboiling is available (degassed conductivity). SWAN has integrated the cation column into the instruments. This results in considerable less maintenance work.

Oxygen (dissolved)

The choice of the instrument depends on cooling water quality and measuring range:

  • For the ppb range use OXYTRACE systems as for boiler feedwater;
  • For ppm use OXYSAFE systems as in potable water.