The handling of multiphase systems applied in mixersettler processes, in which phase separation characteristics are exploited, is to date still a challenge for the chemical industry. Approaches for analyzing the influencing parameters on these systems can be of use, especially regarding equipment design and technical applicability. In this contribution, a guideline is presented and applied in a case study for a surfactant-containing multiphase system implemented in a hydroformylation mini-plant. Herein, the most relevant investigated parameters such as temperature, concentrations of reactants, system pressure, and stirrer characteristics are analyzed. This is followed by an analysis of various internal fittings including their influence on the temperature profile within the settler. The results of the systematic analysis are used to design a highly flexible, modular, and efficient settler for the separation of up to three liquid phases.