High resolution and small volume automatic ultrasonic velocimeter for liquids

A method is described to precisely measure the sound velocity of liquids. The construction of a resonator cell for the simultaneous measurement of a sample liquid and a reference liquid is presented. The non-ideal properties of the cavity resonators are carefully considered for a superior evaluation of the resonance frequency data Also presented is a low-priced electronic set-up, designed for the computer-controlled determination of the complex transfer functions of the cavity resonators and also for automatic temperature monitoring and control. Possible sources of errors are discussed and some representative results are presented in order to illustrate the repeatability of the method and the accuracy of the sound velocity data relative to a reference liquid.