Apparatus for determining the density of liquids and gases from a period of an oscillator filled with a test sample

摘要

A device for determining the density of liquids and gases uses an actuator to physically excite a sample of the material being tested. The oscillations induced by this excitation are detected by a sensor and amplified by an oscillation amplifier, and the amplified signal is used to drive the actuator in a closed-loop fashion. To compensate for errors in the density measurement process arising from non-ideal viscous effects of the sample, a phase change circuit or inverter may be shunted into the amplifier circuit to change the phase of the excitation signal. By observing the effects of the excitation phase change on the oscillation frequency of the sample, the sample's viscosity can be measured, and the system can compensate for its effects.