The use of conventional water-based cleaning strategies such as CIP is largely avoided in chocolate processing due to the risk of microbial growth. For product changeovers on the same plant, dry cleaning methods are therefore used, for example pigging processes, flushing processes or combination of both. In contrast to pigging, flushing processes can, in principle, be applied to most geometries of immersed system components. Due to the complexity and size of the plants, as well as uncertainty about the exact influences in the process, flushing processes are designed with wide safety margins, resulting in unnecessarily high resource consumption. 

This study contributes to reducing this inefficiency by systematically investigating the key influencing factors of conventional flushing processes using a custom-designed experimental setup with dedicated measurement technology. In addition, insights into four alternative flushing strategies are presented. The experimental work examines flushing processes in partially filled pipelines, the use of flushing sequences, the combination of both approaches, and the use of contour-adaptive suspension pigs. The strategies are evaluated using two component geometries: a T-piece and a straight pipe. The results are compared with regard to their potential for resource savings. The aim is to provide a solid basis for the design of product changeovers in the field of chocolate manufacturing.