"The DIS measurement always shows 0 ppm"

Typical Results:

Note: Sensor life expectancy is water quality and application specific. Best practice suggests annual replacement of process dependent sensors.

Follow below flow chart to determine root cause.

The mV signals always have to be positive.

Negative mV signals point to stray currents or chemical interference.

Take a water sample in a beaker and stir the sensor to create some flow – if the signal is still negative, there is a chemical interference (common with Chlorine dioxide measurements).