Viscometer

US6910366B2 · kind B2 · utility

Assignee

• Endress+Hauser Flowtec AG · CH

Inventors

• Wolfgang Drahm · Erding, DE
• Alfred Rieder · Landshut, DE

Key dates

• Filing date: Aug 23, 2002
• Grant date: Jun 28, 2005
• Expiry date: Nov 16, 2022

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N2009/006
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

The viscometer provides a viscosity value (Xη) which represents the viscosity of a fluid flowing in a pipe connected thereto. It comprises a vibratory transducer with at least one flow tube for conducting the fluid, which communicates with the pipe. Driven by an excitation assembly, the flow tube is vibrated so that friction forces are produced in the fluid. The viscometer further includes meter electronics which feed an excitation current (iexc) into the excitation assembly. By means of the meter electronics, a first internal intermediate value (X1) is formed, which corresponds with the excitation current (iexc) and thus represents the friction forces acting in the fluid. According to the invention, a second internal intermediate value (X2), representing inhomogeneities in the fluid, is generated in the meter electronics, which then determine the viscosity value (Xη) using the two intermediate values (X1, X2). The first internal intermediate value (X1) is preferably normalized by means of an amplitude control signal (yAM) for the excitation current (iexc), the amplitude control signal corresponding with the vibrations of the flow tube. As a result, the viscosity value (Xη) provide…