Viscosity and elasticity of a fluid

Abstract

Disclosed herein is a torsion tube apparatus for making on-line measurements of the viscosity and elasticity of a fluid. The apparatus includes a housing member, an outer cylinder having one end rotatably mounted with respect to the housing member, and a motor for rotating this outer cylinder. An elongated torsion tube is mounted concentrically within and spaced from the outer cylinder and has one end fixed to the housing member, with its other end freely disposed within the cylinder for torsional movement with respect to the fixed end. Therefore, an annular void is defined between the tube and cylinder. Fluid may be introduced through a conduit into the interior of the cylinder for flow therethrough and discharge therefrom, such that rotating motion of the fluid caused by rotation of the cylinder exerts a torsional force directly on the outer surface of the tube. A torsion indicating shaft extends concentrically through the tube, having its one end fixed to the free end of the tube. An indicator is fixed to the other end of the shaft. Accordingly, torsional force on the tube provides the sole source of rotative movement of the shaft that is detected by the indicator. The assembly provides a smooth axial path for the fluid which flows through the annular void between the outer cylinder and tube.