In the process engineering of chemistry and petrochemistry, food and pharmaceutical production, biotechnology, the paper and cellulose industry, supply and disposal as well as energy technology, raw material extraction, and agriculture and construction, rotary positive displacement pumps play an important role in transporting, circulating, and dosing. No other type of pump handles such a wide range of fluid properties: from thin to thick, from homogeneous to lumpy, from lubricating to abrasive, from neutral to aggressive. However, rotary positive displacement pumps meet these requirements only with partially very different designs, and the user often struggles to make the right choice for their application. This user manual provides pioneering and helpful services for this purpose. It is written for engineers, technicians, chemists, and physicists in research and development.