Does the Zirkon® DIS Free Chlorine sensor need a zeropoint calibration?

In most free chlorine measurement applications, a zeropoint calibration is absolutely NOT necessary and can lead to problems with the measured value and/or the reference calibration.

The free chlorine measurement is zero-point stable and usually needs only a one point calibration.

WARNING: The zeropoint calibration can have dire consequences if done improperly! If, for example, a zeropoint deviation is due to substances that consume disinfectant and are through that process themselves consumed, it would be wrong to make a zeropoint calibration. Instead, the measurement has to be relocated to a point at which the consumption reaction is already complete!

For zero-point calibration, supply the measuring point with disinfectant-free water that in every other respect and in all measuring conditions corresponds to your measuring water. Removing disinfectant with chemicals on the other hand may change the water and the resulting zero-point.

After a zero-point calibrations you still have to carry out a reference calibration.

IMPORTANT: If following a zeropoint calibration you encounter difficulties with the measurement or the reference calibration, we strongly recommend to undo the zeropoint calibration by disconnecting the cable from the sensor and repeating the zeropoint calibration as soon as the measuring signal has dropped to 0 mV.