The Comparison of Viscosity-Shear Data Obtained with the Kingsbury Tapered Plug Viscometer and the PRL High Shear Capillary Viscometer

Messrs. M. R. Fenske, E. E. Klaus and R. W. Dannenbrink.—The data presented in the attached Figs. 1, 2, and 3 show that the two viscometers yield values of about the same precision and reproducibility. To compare the results from the two different instruments, an average rate of shear must be assigned to the capillary type of viscometer. Values ranging from 0.5 to 0.66 of the maximum rate of shear at the capillary wall have been used as the average rate of shear. This basis appears adequate for the present comparisons given in Figs. 1, 2, and 3. Considering all the variables involved, the differences in equipment and in techniques, and the number of experimental points covered in the two studies, the agreement between the two instruments is good; the maximum difference is about 6 percentage units in viscosity decrease. The agreement between the two instruments is poorest at +210 F with both oils. The best agreement for oil No. 104 is at 150 F and for oil No. 103 at 100 F.