Soap is, quantitatively-speaking, the most produced tenside in the world. It is primarily produced on an industrial scale by way of fatty acid alkaline hydrolysis in continuous operation. This is usually based on vegetable fats such as palm or coconut oil. In the first stage of soap production, these are hydrolytically split into fatty acids and glycerin by hot water vapour in the presence of a catalyst at a pressure of 10 bar in the autoclave. The fatty acid emulsion that forms during alkaline hydrolysis, which often used to be referred to as soap glue, is neutralised with caustic soda or sodium carbonate solution (soda) in the second reaction stage. The viscous substance produced in this way, which already represents the finished soap, is then elaborated into liquid soap in a scrubbing column. In an ancillary process, the glycerine obtained is steamed out to form raw glycerine, which then goes on to be used in a subsequent process.

KROHNE offers a wide range of high-quality flowmeters for soap production based on various, functional measuring techniques for the respective substance consistencies and requirements. These range from viscous liquids, to sludges, highly aggressive and abrasive media or other media with low flow velocities. These measuring devices for maximum performance requirements and precision are available in many versions – some of which feature an integrated temperature or pressure sensor. Soap production in particular requires proper storage of the raw materials and finished products, taking into account temperature, cleanliness and prevention of contamination. The components used to manufacture liquid soap, such as the measuring devices, are often made of stainless steel or special plastic materials, which on request meet the demands for hygienic applications. Most devices also allow the sensor technology to be directly connected to the process control system, not least by means of industrial bus communication.