This paper summarizes studies to determine the stability of water-in-oil emulsions in the OHMSETT tank facility and comparison with laboratory results. The OHMSETT tests were in four series. The tests were one week each in the first year and two weeks each in the second year. The first and second series consisted of 12 experiments each on 6 oils. The third series consisted of testing 9 oils through a series of 16 experiments. In the fourth set of tests, 8 oils were used in 16 experiments. Several of the experiments consisted of leaving the oils for longer periods of time. The rheological properties of the oils were measured and compared to the same oils undergoing emulsification in the laboratory. The oils and water-in-oil states produced were found to have analogous properties between the laboratory and the OHMSETT facility. Comparison of time and work factors showed that the energy in the two test conditions was similar. These tests also provide information on the kinetics and energy levels necessary to form emulsions, which is useful to oil spill modellers. These studies have confirmed previous laboratory studies that show that the stability of emulsions can be grouped into four categories: stable, unstable, meso-stable, and entrained. Water can reside in oil as ‘entrained water', in which larger droplets of water are temporarily suspended by viscous forces. These emulsions and mixtures have been distinguished by physical measures as well as visual differences.

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