Rotary viscometer - where viscosity is measured by speed of rotation of cup filled with ferromagnetic liq. and rotated in liq. being tested by magnetic field

摘要

The viscometer has an outer cup, which is stationary and contains a liq. of which the viscosity, is to be measured. In the outer cup is a coaxial inner cup which floats in the liq. and contains a ferromagnetic liq. Two pairs of Helmholtz coils are located outside the outer cup to create a rotating magnetic field, the liq. being tested forming an air gap. The two cups are pref. made of a material which is electrically and magnetically inactive, esp. transparent methyl methacrylate. The magnetic field pref. has a frequency of 30-200 esp. 100 Hz. and an intensity of 50 gauss. The ferromagnetic fluid is pref. water contg. ferrite grains and possessing a satn. intensity of 140 gauss. Thereis no mechanical contact between the two cups.