Method for determination of concentration

摘要

The percentage of suspended substances in a flowing medium is indicated by illuminating said medium with light perpendicularly to the direction of flow. The light intensity is held mainly constant at a predetermined value. Detection is made by a first light detector of light radiated from the medium in a predetermined direction and the electrical signal obtained is led to a device squaring the effective value of the portion of said signal lying within a predetermined frequency range. The percentage of the suspended substance is obtained from said square of the effective value.