Vibrating element apparatus for fluid density and/or viscosity determination

摘要

Sensor apparatus which may be used for measuring the density and/or viscosity of, for example, frying oils includes two stainless steel tubes 1, 2 closed by caps 3, 4 and fixed to a diaphragm 5, the tubes being immersed in the fluid. An alternating voltage is applied to one of a pair piezoelectric transducers 9, 10 to produce oscillations of the tubes and their vibration is monitored by the other transducer. The difference in phase between the driving voltage and the detected vibration may be used to determine the viscosity of fluid. The tubes are vibrated at varying frequencies, preferably at frequencies above and below the resonant frequency when the tubes are submerged. Different signal processing is adopted if the fluid is of high viscosity and here the resonant frequency and damping constant are derived. IMAGE