A study on the formation and characterization of sprays from emulsions by pressure-swirl atomizers is presented. In preliminary investigations, a rheological and tensiometric characterization of the investigated liquids was carried Out. Tests of the suitability of phase-Doppler anemometry (PDA) for measuring sizes of drops of opaque liquids confirm that PDA is applicable. The first step towards the characterization of sprays from opaque liquids was the investigation of the discharge characteristics of the atomizers. A non-dimensional discharge correlation was developed, which is suitable for determining the second Newtonian plateau viscosity of the sprayed liquid. A second series of experiments revealed a correlation for the non-dimensional global Sauter mean drop diameter as a function of the operation parameters and liquid properties, which allows its prediction with good accuracy. (C) 2009 Elsevier Ltd. All rights reserved.