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The Turbidity Sensor 3712 measures scattered light. This measurement is known to have a good correlation to the amount of suspended matter in water and can be used to monitor sediment, algae, or particle pollution. It is designed for use together with the Aanderaa Dataloggers or Display Units.

The sensor head is cylindrically shaped, molded in Durotong and installed in an adapter made of Titanium. The sensor is furnished with a 10-pin receptacle for connection to the sensor cable. Two light emmiting diodes and one photo diode are pointing towards a common center at an angle of 15°. The photodiode is furnished with a daylight filter. The electronic circuitry is molded in the sensor housing.

When a measurement is taken the IR light emitting diode is switched on for half a second and sends a light beam into the water. If the surrounding water is clean and clear the photodiode will not detect this light. On the other hand, if the water is contaminated, scattered light from particles in the water will be sensed by the photodiode and a photocurrent will flow in the diode. This current gives a signal that signifies the amount of light that has been scattered. The signal is independent of the ambient light intensity and it is fully temperature compensated.

The output is in the standard Aanderaa SR-10 format. The adapter also has a temperature probe measuring the exact water temperature and the output is in the standard Aanderaa VR22 format.

The sensor is designed to avoid marine fouling. In any case, it is important to keep the plastic surfaces, covering the IR-LED and the photodiode, clean to ensure accurate measurements. When exposed to air, the sensor should read 0.1 NTU.