Cooperative test results of apparent viscosity determination at low shear rates using the constant pressure viscometer

Since the introduction of the Constant Pressure Viscometer by Shell Canada Limited in 1972, the instrument has been built and used by three other companies. Originally designed to study the dispensing limits of centralized system greases, this Viscometer has proven to be a reliable tool in determining the apparent viscosity of greases at shear rates below 10.0 s-1. Two round-robin studies have been conducted among the four grease manufacturers. Round-robin testing was done on two different grease samples supplied by two of the participants in the study. Both were NLGI grade 2, lithium based, commercially produced greases. Results of the first study showed good reproducibility among three of the participants.