Patent ID: 6907772

Claim:
An apparatus for determining the viscosity of a non-Newtonian fluid over plural shear rates using a decreasing pressure differential, said apparatus comprising: a non-Newtonian fluid source; a capillary tube having a first end and a second end, said first end being coupled to the non-Newtonian fluid source through a first riser tube, said capillary tube having capillary tube dimensions; a second riser tube having one end coupled to said second end of said capillary tube and another end being exposed to atmospheric pressure, said second riser tube being positioned at an angle greater than zero degrees with respect to a horizontal reference position, said first and second riser tubes comprising a riser tube dimension; a respective sensor for detecting the movement of the non-Newtonian fluid, caused by said decreasing pressure differential, through said first and second riser tubes, respectively, at plural shear rates as the non-Newtonian fluid moves from the non-Newtonian fluid source, through said first riser tube, through said capillary tube and into said second riser tube in a laminar flow, said sensors generating data relating to the movement of the non-Newtonian fluid over time; and a computer, coupled to said sensors, for calculating the viscosity of the non-Newtonian fluid based on said data relating to the movement of the non-Newtonian fluid over time, said capillary tube dimensions and said riser tube dimension; and wherein said laminar movement of the fluid through said riser tubes comprises: a rising fluid column in said second riser tube and wherein its corresponding sensor monitors the changing height of said rising fluid column over time, said height being defined as the distance between the top of said rising fluid column and a horizontal reference position; a falling fluid column in said first riser tube and wherein its corresponding sensor monitors the changing height of said falling fluid column; and said monitored changing height of said rising fluid column and said monitored changing height of said falling fluid column forming said fluid movement data.