Abstract: An inline fluid properties measurement device that includes a tube defining an interior space that includes at least one non-cylindrical volume, and having a fluid entrance and exit, and capable of conducting fluid from the fluid entrance to the fluid exit, through the at least one non-cylindrical volume. An excitation and sensing transducer assembly is positioned to torsionally drive the tube and to sense torsional movement of the tube and a controller is programmed to drive the excitation and sensing transducer to drive the tube in torsion, thereby translating the fluid in the at least one non-cylindrical volume, and to sense torsional movement of the tube, thereby producing a sense signal. Finally, a signal analysis assembly responsive to the sense signal to form a measurement of at least one property of the fluid.

Abstract: An inline fluid properties measurement device that includes a tube defining an interior space that includes at least one non-cylindrical volume, and having a fluid entrance and exit, and capable of conducting fluid from the fluid entrance to the fluid exit, through the at least one non-cylindrical volume. An excitation and sensing transducer assembly is positioned to torsionally drive the tube and to sense torsional movement of the tube and a controller is programmed to drive the excitation and sensing transducer to drive the tube in torsion, thereby translating the fluid in the at least one non-cylindrical volume, and to sense torsional movement of the tube, thereby producing a sense signal. Finally, a signal analysis assembly responsive to the sense signal to form a measurement of at least one property of the fluid.

Abstract: An inline fluid properties measurement device that includes a tube defining an interior space that includes at least one non-cylindrical volume, and having a fluid entrance and exit, and capable of conducting fluid from the fluid entrance to the fluid exit, through the at least one non-cylindrical volume. An excitation and sensing transducer assembly is positioned to torsionally drive the tube and to sense torsional movement of the tube and a controller is programmed to drive the excitation and sensing transducer to drive the tube in torsion, thereby translating the fluid in the at least one non-cylindrical volume, and to sense torsional movement of the tube, thereby producing a sense signal. Finally, a signal analysis assembly responsive to the sense signal to form a measurement of at least one property of the fluid.

Abstract: A method of measuring properties of a fluid that uses a conductor electrically connected to a current source. A magnetic field is created about the conductor and the conductor is introduced into the fluid medium. A current waveform, having a frequency, is periodically passed through the conductor, so as to cause the conductor to move, due to force exerted on the conductor from interaction of the current and the magnetic field. The conductor movement is sensed, producing a sense signal that is amplified into an amplified sense signal. The phase relationship between the current waveform and the amplified sense signal is measured and the current waveform frequency is adjusted to create a phase lock loop. The frequency when the phase lock loop is in lock state is measured as the phase between the excitation and the measured sense signal is varied, and fluid properties are calculated from the measured frequencies.

Abstract: A system for measuring damping and that includes an oscillator that produces an excitation signal for a resonator that can be placed in a damping medium. A sensor produces a sensor signal responsive to resonator motion. Also, a timing circuit ensures that excitation and sensing occur during mutually exclusive periods. An amplifier responds to the sensor signal, producing an amplified sensor signal. A phase detector is adapted to measure the phase relationship between the excitation signal and the amplified sensor signal and a controller is responsive to the phase detector to adjust the excitation frequency of the excitation signal, to create a phase lock loop. An integrator receives the amplified signal during periods that are mutually exclusive to and interleaved with the excitation. This integrator produces an integrated DC and low frequency component of the amplified signal, which is subtracted from the input amplifier input.

Abstract: A resonator (1) is vibrating close to its resonance frequency. The vibration is excited by one or a first transducer (2) connected to an oscillator (11). The vibration is measured by the transducer (2) or a second transducer (3) and stabilized by a phase-locked feedback loop comprising a phase sensitive detector (33), a feedback controller (36), a phase shifter (17) and means (15) to evaluate the measured frequencies. In order to measure the damping of the resonator (1), the phase in the phase shifter (17) is alternately set to two different values. The difference between the frequencies corresponding to these two phase values is a measure for the damping of the system. One or more switches (19, 28, 27) and a gate generator (16) make sure that excitation and measurement do not occur at the same time. Thereby, any cross-talk between driving and sensing transducers is completely eliminated. Also, a single transducer can be used to both excite and measure the vibration.

Abstract: A resonator in the form of a cylindrical body is immersed in a fluid to be measured and excited by a piezoelectric transducer in the vicinity of its natural frequency. The vibration frequency is stabilized by a feedback loop. In that feedback loop a phase shift is introduced which can be switched between to discrete values. The resulting difference in frequency of oscillation of the resonator is proportional to the damping ratio of the resonator and is, therefore, a measure for the viscosity of the fluid. The natural frequency of the piezoelectric transducer is substantially higher than the natural frequency of the resonator, and the oscillation of the resonator is mechanically isolated from the housing by an inertial mass - spring arrangement with low natural frequency.