This contribution presents a standardized experimental setup for the development of gravity separators. Two different optical measurement techniques for the characterization of the inlet and outlet dispersion with a droplet spectrum of 20‐2000 μm are used. The settling behaviour in a standardized batch settling test (ERICAA cell) serves as a basis for predicting the drop diameter resolved separation efficiency of a horizontal continuous separator. The latter (DN150, length 0.65 m) was operated and monitored with a phase fraction of up to 15% and a load of up to 17.0 m3 m−2 h−1. A paraffin oil with a viscosity of 10 mPa s was the dispersed and water the continuous phase. Sauter mean diameters of dispersions measured inline show a good agreement with those calculated from batch settling tests. Additionally, the modelled separation efficiencies are compared to the experimental results produced with the continuous separator.