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The pH electrode S401 DIG and the ORP electrode S406 DIG are suitable for the measurement of pH and ORP in various applications.

The porous liquid junction resists fouling and chemical attack. The double junction of the reference electrode increases the operating life in applications containing sulphides (H2S) and metals such as lead, mercury and silver.

The new type of solid reference electrolyte allows a reference potential constant in time and at pressure and temperature variations.

The new capillary temperature sensor design places the Pt100 behind the (pH or ORP) sensitive membrane for accurate temperature compensation and measurement.

The mechanical protection IP68 protects the high impedance signal of the electrodes from moisture that can be generated in immersion applications (condensation).


  • Drinking water
  • Process water
  • Waste water
  • Samples containing sulphides and metals such as;
  • Mercury
  • Lead
  • Silver
  • Waste Water
  • S401 DIG & S406 DIG Technical specifications

    Models S401 DIG S406 DIG
    Measuring range 0…14 pH -1500.....+1500 mV
    Measuring method Potentiostatic
    Accuracy 0.05 pH ± 5 mV
    Repeatability ± 0.05 pH
    Response time T90 < 60s
    Operating temperature 0…80 °C in insertion/by-pass • 0…50 °C in immersion
    Maximum pressure 6.9 bar
    Body material Ryton® and PVC
    Measuring electrode Hemispherical glass membrane
    Other materials Teflon®, carbon, epoxy
    Mechanical protection IP68 Sensor + cable
    Power supply 12…24Vdc
    Power consumption max. 2W
    Cable 10m integral with the sensor (other on request)
    Signal interface Modbus RTU Standard Protocol
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