Based on this experience the SORTER of Loptex which previously used only optical sensors was modified in order to receive an additional acoustic sensor. The machine is now offered under the denomination SORTER „Optosonic“.

The cotton conveyed will first pass through the acoustic and then the optical sensor. In contrast to the optical sensor, which is installed as a double version, a single acoustic sensor is sufficient as sound waves largely penetrate well opened, fibrous material. Opposite of the acoustic sensor there is a recess in the channel filled with a material absorbing the emitted sound waves. This appears to be necessary because otherwise they would be reflected by the metal walls.

Picture 4: Measuring channel of the SORTER Optosonic

1. acoustic sensor

2. optical sensor

3. pneumatic valves

4. waste container

5. absorber box

The application of two different measuring methods does not result only in the detection of coloured and colourless impurities but on the whole in a more effective since doubled inspection.

There  is a wide range of detection where optical and acoustic means overlap.

There is e.g. synthetic contamination which is coloured, or there is non-synthetic contamination which has a hard surface. Since such cases are detected by both measuring methods, the material is checked twice which will result in an overall higher efficiency of the machine.