AUTOMATION OF AN ULTRASOUND VELOCITY-MEASUREMENT SYSTEM IN HIGH-PRESSURE LIQUIDS

A system for the measurement of ultrasound velocity in liquids was aut omated to cope with variations in temperature (293.15 K less than or e qual to T less than or equal to 373.15 K) and pressure (P less than or equal to 100 MPa). The following problems had to be solved: supervisi on and monitoring of the achievement of the required pressure and temp erature, creation and reception of the signal, acquisition of the meas urement points, identification of the signal received on the basis of the characteristics of a reference signal, measurement of ultrasound t ravel times, memorization and processing of the results. The system en ables substantial savings of time compared with manual methods. The sy stem calibration procedure is also described. Measurements of octane a nd pentane (which had been studied previously) are used to verify the validity of the system developed and to determine its degree of accura cy (absolute average deviation from literature data 0.1% and maximum d eviation from literature data 0.25%).