What happens in the coupling reactor is the core reaction of dye manufacturing, that is, the coupling reaction, through which the azo dye (synthetic dye) is generated, and it is processed into various colors of pigments in the subsequent process. A stirring device in the reactor is used for continuous mixing of azo dyes. In addition, the process also needs to be cooled, otherwise the various substances in the reaction will decompose. Level measurement is essential to the stable operation of this process.