Residual chlorine sensors are based on different measuring principles, can be divided into diaphragm polarographic sensor and constant voltage sensor.

Used for continuous monitoring of residual chlorine.

  1. diaphragm polarographic sensor, cathode, anode, electrolyte and cathode covered with a layer of gas permeable thin film composition. The remaining chlorine in the tested solution diffuses to the cathode through the diaphragm, and the cathode and anode are appropriate the polarization voltage can reduce the residual chlorine at the cathode, and these chemical reactions occur in the residual chlorine in the measured solution chlorine is proportional to the current.
  2. constant voltage sensor, composed of two platinum electrodes and a reference electrode to form a microbattery measurement system. During measurement, a stable electrical potential is maintained at the measuring end of the electrode, and different components are produced under this electrical potential generate different, well linear current intensities.
  • polarographic sensor is characterized by:
    • Sensitive reaction, high accuracy, good stability
    • Simple operation and small maintenance
    • Suitable for all kinds of media, film is not easy to damage, pollution resistance
  • constant voltage type sensor is characterized by:
    • With stable zero performance, to ensure accurate and reliable measurement
    • Simple structure, easy to clean
    • It is suitable for measuring residual chlorine, chlorine dioxide and ozone in water


  1. Zero point correction

Zero correction with chlorine-free water

  1. Slope correction

Actual measurements are made in a portable or laboratory setting

Make alignment

Matters needing attention:

  1. PH should be controlled at 5-8pH
  2. The flow should be controlled at 60-80L/H
  3. The pressure is within 4bar

Read more about water quality:

Turbidity meter working principle
Main water quality indicators
What is salinity meter?