Automated densimetric system: Measurements and uncertainties for compressed fluids

In this work, we present the automatization of a densimetric system for pVT measurements of compressed fluids, operating over the temperature range from 283.15 K to 398.15 K and pressures up to 70 MPa. The heart of the automatic assembly is a commercial Anton Paar DMA HPM vibrating-tube densimeter. The densimeter was calibrated using the method developed by Lagourette et al. and modified recently by Comuñas et al. The fluids used in this calibration were a vacuum, water, and n-decane. Data reliability has been verified by comparing our experimental results for toluene with literature data. The uncertainty of the experimental density was evaluated following the rigorous procedure of the EA-4/02 guide. Moreover, new density measurements of pentaerythritol tetrapentanoate ester are presented. For this fluid with significant viscosity values, a correction factor was applied to take into account the damping effects in the densimeter cell.