METHOD OF ISOLATING SURFACE TENSION AND YIELD STRESS IN VISCOSITY MEASUREMENTS

摘要

A method for isolating surface tension effects and/or yield stress of a fluidflowing in a U-shaped tube wherein one or both legs of the U-shaped tube is monitored over time for the changing height of the respective fluid columns therein. A portion of the U-shaped tube comprises a flow restrictor, e.g., a capillary tube, of known dimensions. Monitoring one or both of the moving fluid columns over time permits the viscosity determination of the fluid flowing therein over a range of shear rates from fluid column height differences. However, it is necessary to isolate the effects of surface tension and/or yield stress to obtain an accurate viscosity determination. The method provides for the surface tension effect being subtracted from the difference in fluid column heights and then any yield determining stress effect. Alternatively, the method also provides a process for determining both the surface tension effect and yield stress effect simultaneously.