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Turbidity refers to the scattered component of a light beam which is diverted away from its natural course by optically denser particles in the medium (e.g. solid matter particles).

The measurement is performed by using a 90° scattered light method compliant with ISO 7027 / EN 27027. The measuring method is based on the Tyndall effect. The turbidity of the medium is determined by the amount of scattered light.


  • Untreated water
  • Surface water
  • Process water
  • Industrial or municipal water treatment plant discharge
  • S461 TN Technical specifications

    Measuring range 0…1000 NTU / 0…4000 NTU
    Measuring method 90° Scattered light
    Resolution 0.01 NTUfor 0…1000 NTU range
    0.01 NTUfor 0…4000 NTU range
    Accuracy ±2% for 0…1000 NTU range
    ±5% for 0…4000 NTU range
    Repeatability ±5 NTUfor 0…1000 NTU range
    ±20 NTUfor 0…4000 NTU range
    Response time T90 < 60s
    Operating temperature 0…50 °C (0…75 °C with body in SS316)
    Maximum pressure 4 bar
    Body material Black PVC and SS316 (on request only SS316)
    O-Rings Viton® and Silicon
    Optics Special Glass with oleophobic treatment
    Mechanical protection IP68 Sensor + cable
    Power supply 12…24Vdc
    Power consumption max. 3W
    Cable 10m integral with the sensor
    Calibration 1-point and/or 2-point for scale
    Signal interface Modbus RTU Standard Protocol RS485
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