Balanced torsionally oscillating pipe used as a viscosity sensor

Abstract

We present a robust viscosity measurement system based on a torsionally oscillating pipe. The sensitive surface of the sensor performs periodic movements in the fluid to be sensed, generating a shear wave that penetrates the fluid. Due to this interaction, the resonance characteristic of the structure is affected, in particular the quality factor decreases with increasing viscosity. The pipe is mounted at its center where it features a nodal point of the preferred resonant mode, reducing temperature issues while simultaneously enabling high quality factors. A mathematical model is presented illustrating how different parameters influence the sensitivity of the sensor. Long-term measurements were performed to demonstrate the time stability of the sensor setup.

6.3.2 Accuracy study of a torsionally oscillating pipe viscometer

“…The range was chosen to provide a large viscosity range but does not represent the limits of the sensor. As shown in [6] also lower viscous fluids with viscosities of 1.96 mPa.s and below are measurable and also higher viscous fluids with viscosities up to 21.5 Pa.s were already measured. The measurements were performed using the MFA200 analyzer from Microresonant (presented in [7] and [8] www.microresonant.at) and an automated sampling system.…”

“…The mounting spring placed in the middle of the oscillator is not moving. A more complex model including the interaction with the fluid was presented in [6].…”

“…These high resonance frequencies result in a low penetration depth and therefore a very thin fluid layer being sensed directly on the surface of the sensor which leads to spurious influences due to surface contamination. In this contribution we present an accuracy study of our recently presented viscosity sensor based on a torsionally oscillating pipe [5] and [6] with a low resonance frequency around 7.7 kHz. The sensor setup is almost completely machined in aluminum and is actuated and read out electromagnetically.…”

Mechanically flexible viscosity sensor for real‐time monitoring of tubular architectures for industrial applications

“…Moreover, viscosity analysis is employed to ensure product consistency as a quality indicator within the industrial production process, such as in petrochemical, 3‐5 polymers, 6‐8 and food industries 9‐11 . Capillary methods, 12,13 falling‐object methods, 14,15 vibrational, 16‐18 optical 19‐21 and torque detection are various known and reliable techniques for measuring the viscosity using an off‐line workstation setup 22‐24 . The conventional approach for the viscosity measurement procedures in industries starts with on‐site sample collection, followed by laboratory analysis, and, sometimes, requiring sample preparation before examination; it ends with sending the results' report to the site for decision‐making 25 .…”

Analysis of a Tubular Torsionally Resonating Viscosity–Density Sensor

“…Probe-style sensors are already commercially available (e.g., Rheonics, Hydramotion, Sofraser, Brookfield, and Emerson). Experimental and numerical studies have been conducted on how to measure viscosity [25][26][27][28][29]. Furthermore, they have been used to characterize viscoelastic fluids [21].…”