Patent ID: 7980118
Filing Date: 2011-07-19
Classification: G01N

Abstract:
1. A method of estimating an apparent viscosity of a non-Newtonian fluid by using test apparatus, said test apparatus comprising a conduit for receiving said fluid under pressure, said conduit having an inside diameter D, a length L and a L/D ratio greater than 40, a valve system operable in a first mode to block fluid flow in the conduit to allow fluid to accumulate under pressure in a pressure zone of the conduit and in a second mode to vent the pressure zone of the conduit, and a pressure measuring device for measuring the pressure inside the pressure zone of the conduit, said method comprising: a) with said valve system operating in its first mode, supplying fluid under pressure to said conduit until the fluid in said pressure zone reaches a predetermined pressure; b) operating said valve system in its second mode to vent the pressure zone of the conduit for a predetermined time interval during which there is a transition between non-Newtonian flow and Newtonian flow; c) using said pressure measuring device, measuring the pressure P in said pressure zone during said transition; d) calculating a wall shear stress τ of the fluid based on the conduit length L, the conduit diameter D, and the measured pressure P during said transition; and e) determining an estimated apparent viscosity η