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S423 C OPT is an oxygen measuring sensor with integrated temperature probe. The measuring technique is based on the following optical principle: a diode emits a blue light towards a support on which a fluorescent substrate is applied.

The substrate reacts by emitting initially a red light (luminescence), then returns to its initial state. The intensity of the produced red light and the return rate to the initial state are related to the present oxygen concentration. This innovative method allows reliable, accurate measurements with no drift over time, so that the system calibration is no longer necessary.

No maintenance is required except for the replacement of the luminescent support about every two years. The system does not consume oxygen, therefore it is suitable for the most varied fields of application, including those in which the measuring liquid is almost stationary.


  • Surface water
  • Drinking water
  • Fish farming
  • Waste water
  • Sea Water
  • Available versions

  • with PVC body, with 4…20mA outputs
  • S423 Technical specifications

    Measuring range 0.00…20.00 mg/l
    Measuring method Optical measure by luminescence
    Accuracy ± 0,2 mg/l when < 5mg/L ± 0,3 mg/l when > 5mg/L
    Response T90 < 60s
    Refresh time < 1s
    Temp. compensation with internal NTC probe
    Operating temperature 0…50 °C
    Maximum pressure 5 bar
    Body material SS316 (PVC body optional)
    Electrode material Special optical glasses
    O-Rings NBR and Silicon
    Mechanical protection IP68 Sensor + cable
    Power supply 12…24Vdc
    Power consumption max. 2W
    Cable 10m integral with the sensor
    Signal interface RS 485 Modbus RTU Protocol
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