An Automated Vibrating-Tube Densimeter for Measurements of Small Density Differences in Dilute Aqueous Solutions

The core of the automated apparatus is a high-temperature high-pressure densimeter with a metal vibrating tube designed for accurate flow measurements of densities of liquids in the temperature range from 298 to 573K and at pressures from 0.1MPa up to 30MPa. The densimeter is being employed for a study of dilute solutions of aqueous solutions of organic substances where the density difference {solution–water} is a primary experimental quantity. Consequently, partial molar volumes of solutes at infinite dilution in water are evaluated from the measured data. Two sampling sections are connected in series in the filling line of the densimeter. One of them is employed for manual filling of the measured sample into a sampling loop using a syringe. The other section allows fully automated measurement of up to 12 samples in one run. The recorded data are evaluated after the automated run is completed.