making waves in sensor technology

The XL7 viscometer is in a class of instruments called vibrational or resonant viscometers. Vibrational viscometers work by creating waves — but it turns out that the type of wave is very important. Not just any wave will do.

Viscosity is a shear measurement. It can only be truly assessed under shear conditions, so we use shear waves. There are many other types of vibrational waves but these are avoided as they can behave unpredictably in process environments.

To the naked eye, nothing moves. The solid stainless steel sensor element is submerged in the fluid and made to move back and forth microscopically at a high frequency. This is called “resonance”. As the surface of the sensor shears through the liquid, energy is lost to the fluid because of its viscosity.

The dissipated energy is accurately measured by microprocessor-controlled electronics and then equated back to viscosity. Higher viscosity causes a greater loss of energy and hence a higher reading.

The harnessing of the wave dissipation principle with solid engineering design gives Hydramotion viscometers a rare combination of incredible sensitivity and toughness.