A viscometer for use at high temperatures and pressures

Abstract

The theory, development and technical details of a viscometer suitable for measuring the viscosities of silicate melts is described. The viscometer, as described, is essentially a torsionally oscillating rod, driven by a composite piezoelectric oscillator. This arrangement enables the viscosity and shear modulus of both non-elasticoviscous and elasticoviscous fluids to be determined quickly and accurately under a wide range of operating conditions. The equations relating the measured Q and period to the fluid viscous properties are derived and the resulting viscosities for a variety of fluids at room temperature and elevated temperatures confirmed to within 1% and better, by comparison with literature values. Experimental arrangements suitable for high temperature and pressure conditions are discussed.