Application of a micro-(p, V, T) apparatus for measurement of liquid densities at pressures up to 500 MPa

A new Micro-(p, V, T) apparatus, based on the piston-in-a-bottle design, ha s been developed for measurement of liquid densities at pressures up to 500 MPa. The temperature range corresponding to complete immersion of the cell in the thermostat fluid is from T = 263 K to T = 333 K. Friction problems are overcome by having a rotating piston, with varying rotational speeds av ailable. The sample size is about 0.8 cm(3). Results for freezing pressure are reported for (n-hexane + n-hexadecane). Calculation of the effects of a n increase in pressure and change in temperature on the components of the c ell leads to the determination of liquid densities at pressures up to 500 M Pa which agree within +/-1.5 per cent with reliable literature values. This can be improved to better than +/-0.4 per cent by calibration, as is demon strated by comparison of measured densities for n-octane with bellows volum ometer data. (C) 2000 Academic Press.