A Wide-Range (up to 10¹⁰ P) Rotating Cylinder Viscometer

The range of a high temperature rotating cylinder viscometer has been extended so that viscosity measurements can be made between 10⁰ to 10¹⁰ poises to within 2-percent accuracy. This involves three different techniques. After a calibration constant has been determined for the apparatus in the standard oil range, the other two constants for the higher viscosities were self-determined. In making measurements at the low viscosities, 10⁰ to 10⁵ poises, the outer cylinder is rotated at constant speed and the torque measured on the inner cylinder; from 10^4.5 to 10^7.5 poises the inner cylinder is rotated through an angle and timed as it returns to its zero position, and from 10^5.5 to 10 ¹⁰ poises the inner cylinder is driven through an angle at constant torque and timed as it traverses this angle. The Fulcher equation viscosity values obtained from previous measurements on Standard Glasses No. 710 and No. 711 by the fiber elongation and rotating cylinder methods have been compared with the present results.