Dean Stark | Water content of emulsion

The test, described in standard EN 1428, consists in determining the water content of bitumen emulsions by distillation with Dean Stark, in order to deduce the content of binder (bitumen). The content of binder in emulsions is an important parameter, specified in the tables of standard EN 13808, and which must be controlled as part of the control of factory production.

The water in the sample is entrained by refluxing a water-immiscible liquid entrainment solvent (azeotropic distillation). The condensed water and solvent are continuously separated in a recipe tube. 25 ml graduated every 0.1 ml. Water collects in the graduated part of the recipe tube and the condensed liquid entrainment solvent, as well as any fluxes and solvents, return to the flask. In this way, only the water is entrained.

The duration of the test is approximately 1.5 hours, and requires the use of toxic solvents such as toluene or xylene. The test must be carried out under an extractor hood to protect the operators, who must ensure that the boiling remains under control. It is the reference method for determining the water content of emulsions.

EN 1428