A System for Viscosity Measurements at Pressures up to 3 GPa and Elevated Temperatures

A falling body viscometer was developed to measure viscosity of lubricants between 10-1 to 105 Pa.s at high pressures (up to 3 GPa) and temperatures of 20–200°C. The viscometer was incorporated into a variable-support pressure vessel mounted in an O-frame press. A solenoid is used to raise the falling soft iron plunger to its upper position, where it closes a pair of contacts. On deactivating the upper solenoid, the plunger, falls to the lower position to close a second pair of contacts. Fall times are measured by a timer in 0.1s increments. Viscosity of a few fluids, namely a synthetic turbine engine oil, a mineral oil, white gasoline and a 1:1 mixture of the mineral oil and white gasoline were measured to demonstrate capability of the system. For the synthetic turbine engine oil, isoviscous curves for 102, 103 and 104 Pa.s are presented on a P–T diagram and estimates are made of the viscosity at which dynamic effects can be expected.