Measurement and Prediction of Viscosity-Pressure Characteristics of Liquids

Abstract

The successful application of a precision capillary-type pressure viscometer in the measurement of viscosity-pressure characteristics of a variety of fluids over the range of 0 to 10,000 psig is demonstrated. A number of pressure-viscosity values determined for about ten different chemical types of fluids provides the basis for the development of a graphical relationship involving the logarithm of viscosity, the pressure coefficient, and the viscosity temperature properties (ASTM slope) of the fluid. A second-degree polynomial equation in conjunction with a digital computer program allows one to calculate the pressure coefficient and, therefore, the viscosity values of fluids at 100 deg F and pressures up to 10,000 psig. The derivation of an exponent for the pressure coefficient extends the ability to calculate values over a range of temperatures. Primary data from three sources are used to compare and contrast these methods with those proposed by several other investigators.