Electromagnetically spinning viscometer designed for measurement of low viscosity in low shear rate region

The electromagnetically spinning method for measurement of fluid viscosity was improved to obtain accurate values of low viscosity in the low shear rate region. Harmful effects derived from the mechanical friction to the smooth rotation of the rotor are thoroughly eliminated by employing a viscosity probe suspended by a thin metal wire. In our previous study, the motion of the meniscus of the sample surface also acted as a troublesome resistant torque for probe rotation, which was addressed by employing a sandwiched structure of the disk probe between the bottom and top plates. The measurements were carried out in two procedures. In the freely oscillating operation, we could measure the viscosity of the atmosphere with a viscosity of approximately 1/100 of that of water. The second type of quasi-steady measurement enabled a measurement of pure water in the range of shear deformation rates smaller than 1 s−1.