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June 2022 – TD 320 OPERATING MANUAL – TURBIDITY SENSOR 4296
Short Description and Specifications
1.1
Description
The Aanderaa Turbidity Sensor 4296 are measuring optical backscatter in water.
Turbidity is the optical property of the water that causes light to be scattered by suspended
particles. High particle concentration causes high turbidity. By establishing the relationship
between turbidity and the local suspended matter this measurement can be used for assessing
the concentration of suspended matter.
The Turbidity Sensor 4296 measures the backscatter of infrared light.
A high efficiency light emitting diode is used to transmit modulated light into the water. The
backscattered light is picked up by a sensitive photodiode and this signal is then conditioned,
linearized and converted to data in engineering unit (FTU). In addition to turbidity, the sensor also
measures water temperature.
An FTU calibrated sensor will not be directly comparable to a NTU or FNU sensor since they are
only identical when measuring in Formazin. The measurement principle is different for the three
methods. For all other liquids except Formazin they will be different and there is no direct
correlation between the three methods.
The sensor is measuring approximately 35mm away from the sensor bot also objects close to this
point may influence the reading. This means that you should always try to mount the sensor with
free view.
1.2
Sensor versions available
The sensor is available with four different ranges:
4296
0-25
FTU
4296A
0-125
FTU
4296B
0-500
FTU
4296C
0-2500
FTU