Method for detecting gas bubbles in liquid medium in container during e.g. fermentation process, involves determining presence of gas bubbles in liquid medium and/or proportion of gas bubbles in medium

摘要

The method involves stimulating an oscillating unit i.e. membrane (11), by an excitation signal during a measuring phase to produce a reception signal. The oscillating unit is stimulated by another excitation signal during a detection or cleaning phase to produce another reception signal, where the two excitation signals differ from each other. A process variable is determined from the former reception signal. Presence of gas bubbles (5) in liquid medium (4) and/or proportion of the gas bubbles in the medium are determined from the two reception signals.