A novel pycnometer for density measurements of liquids at elevated temperatures

A novel pycnometer has been designed for density measurements at elevated temperatures (up to T=473.15 K). The pycnometer consists of a stainless steel cell connected to a small-bore tube. The main feature of the design includes a bored-through expansion fitting, which allows the overflow due to thermal expansion from the cell (via the small-bore tube) to collect in a pressurized line. Densities were measured for pure 1-butanol, pure n-heptane, and for mixtures {x_bCH₃(CH₂)₃OH + (1−x_b)CH₃(CH₂)₅CH₃}, from T=316.85 K to T=458.15 K, at a pressure of 4.93 MPa. Excess volumes were calculated and reported for these mixtures.