This article considers the problem of assessing the energy efficiency of installations for the preparation of liquid feed mixtures of continuous and batch action. The lowest total energy consumption for the unit, productivity, allowing to work under changing conditions at a necessary mode; the best quality of mixing and dissolution, determined by a stable state of the mixture; free access to the working bodies of the unit for its quick cleaning, washing and troubleshooting; the minimum dimensions and weight and the lowest energy consumption for the drive of the unit are determined.