Testing for Solubility, Dispersibility, Emulsion, and Foaming

Solubility, dispersibility and emulsion-forming properties of an inhibitor may be determined in simple bottle tests. Either the actual fluids of interest or some closely simulating them may be used. 

The inhibitor is added to bottles at varying concentrations and the bottles are shaken and then observed for total solubility or dispersibility, and the time for the dispersion to separate. If two-phase systems are involved, both should be included in the bottle to find the effects of emulsion formation. 

For example, for oil-field use, the bottle tests may include either high or low molecular weight hydrocarbons, aromatic or aliphatic hydrocarbons, brine and mixtmes of brine and hydrocarbons. 

More elaborate equipment is required to determine certain other properties. The ASTM D-2550 test describes a method to determine water tolerance in jet fuels in which the fuel is emulsified, filtered, separated, and the remaining entrained water is measured as turbidity by a photocell. A less-stringent test for water pick-up is described in ASTM D-2550, where steam is sparged into the hydrocarbon phase and time of cloudiness is measured. Detergency is difficult to evaluate in equipment other than that being treated. In the petroleum industry, detergency of fuels is evaluated in small-scale engines. 

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