SIGRIST is recognized as a manufacturer offering highly sensitive and accurate turbidity meters to measure lowest turbidity values in water treatment works.
Measuring raw or waste water with turbidity values from 50 up to several hundred FNU require additional measures on the design of an online sensor. Cleaning systems such as wipers or ultra sonic can only deal to a certain extend with deposits and the resulting falsification of the results. The only sensible way is avoiding contamination right from the beginning.
SIGRIST introduced as the first manufacturer true contact-less measurement in a free-falling water stream already decades ago. In the mean time, various supplier offer instruments with non-contact measuring principle. In most cases, the light source and the receiver are indeed not in contact with the medium. However, the water is typically measured in an overflow measuring chamber, in which eventually sediments will settle within a short period of time, making frequent cleaning necessary. Because of the sediments, stray light is produced which adds a drift to the measured values.
Due to the design of the AquaScat models HT and WTM, contamination is not possible. Since the measuring light passes through the entire sample beam, there is no selection of the sample at the surface. The entire water beam is measured and hence, the measurement is representative. The result: reliable and maintenance-free operation over several months.
The picture shows the real use of an AquaScat HT for the measurement of waste water with a turbidity value of 3500 FNU.