Abstract: The present invention relates to a method for determining the density of a liquid using a falling needle viscometer. The viscometer includes a vertical cylinder which is filled with the liquid the density of which is to be determined. Using a funnel at the top of the cylinder, a first needle having a known density is allowed to fall through the liquid in the cylinder. The time that the needle falls between two marks, or transducers, spaced on the cylinder a known distance is measured from which the velocity of the needle through the liquid is calculated. Then a second needle having the same dimensions as the first and a known density different from that of the first needle is allowed to fall through the liquid. The time that the second needle falls between the two marks on the cylinder or transducers is measured and the velocity of the second needle through the liquid is calculated.

Abstract: The present invention relates to an apparatus and method for determining the viscosity of Newtonian and non-Newtonian fluids. More particularly, the present invention relates to an apparatus and method for determining the viscosity of a fluid by measuring the time of fall of a needle through a predetermined distance of the fluid held in a container. The method further provides exact equations according to a modified power law model and Ellis model for the calculation of viscosity, shear stress and shear rate.