DENSITY AND VISCOSITY SENSOR Russian patent published in 2010 - IPC G01N9/00 G01N11/00 

FIELD: physics.

SUBSTANCE: sensor is based on use of mechanical elements which vibrate in the measured fluid medium and can be used to measure density and viscosity in oil refining, chemical, food industry etc. The sensor has a resonant element, an actuating/detecting element, a housing which forms a chamber. The housing has a region with small thickness which forms a membrane. The actuating/detecting element is placed inside the chamber so that it is insulated from the fluid medium F and mechanically connected to the membrane. The resonant element is made with possibility of immersion into the fluid medium F and is mechanically connected to the membrane through a first yoke plate. The membrane has thickness which enables transmission of mechanical oscillations between the actuating/detection element and the resonant element. The method of measuring density and viscosity of the fluid medium includes the following steps on which: an exciting signal is transmitted to the resonant device; a reception signal transmitted by the resonant device is detected; the exciting signal transmission step and the reception signal transmission step are repeated at different frequencies; the inphase actual response of the sensor and the quadrature actual response of the sensor are determined based on the reception signal detected in the frequency range. The method also includes additional steps on which: the inphase model response of the sensor and the quadrature model response of the sensor are calculated; the inphase model response of the sensor is compared to the inphase actual response of the sensor and the quadrature model response of the sensor is compared to the quadrature actual response of the sensor by determining the conjugated correlation coefficient; the calculation step and the comparison step are repeated at a different resonance frequency and different Q-factor and the defined number of resonance frequency, Q-factor and conjugated correlation coefficient is recorded; the final resonance frequency and final Q-factor of the resonant element are determined; density and viscosity of the fluid medium are determined based on the final resonance frequency, final Q-factor and analytical modelling of the resonant element, which is done with the possible degree of accuracy.

EFFECT: simplification of a sensor for use in sampling chambers or small pipes under high pressure and temperature.

15 cl, 30 dwg