On-line acoustic viscometry in oil condition monitoring

The paper describes the theoretical standpoints of developing magnetoelastic viscometers and a concept of viscosity measurement. The magnetoelastic viscometer has shown the readings close to the capillary viscometer. Testing of the oils with PMMA viscosity-index improvers by viscometers has indicated changes in rheological properties observed in the non-Newtonian behavior of the oils. With increase in content or molecular weight of the improver, the non-Newtonian behavior of the oil appeared at lower frequencies of viscosity measurements.

► On-line magnetoelastic viscometer and a concept of viscosity measurement are developed. ► The capillary and solid-state acoustic viscometers are compared to the developed magnetoelastic one. ► Magnetoelastic viscometer yields the data close to the capillary method within 17–500 cSt range. ► The solid-state acoustic viscometer gives the least validity in measuring viscosity above 300 cSt. ► Oils with VI improvers start to reveal non-Newtonian behavior at lower measurement frequencies.