Measurements of rheological fluid properties with the falling needle viscometer

Abstract

The use of data from the falling needle viscometer to determine the rheological properties of purely viscous non-Newtonian fluids is described. From the solution of the basic flow equation, which is given in tabular and graphical form, a method is presented to determine rheological flow curves for both power law and more generalized rheological fluids. The use of the instrument to determine the zero shear rate viscosity is also described and a method of fitting appropriate constitutive equations to the data is discussed and illustrated by examples. Finally, a technique for measuring fluid densities using the falling needle viscometer is presented that is applicable to both Newtonian and power law fluids.