IHS ESDU Vapour pressures and critical points of liquids. Polycyclic phenyl and cyclohexyl compounds. 94001

ESDU 94001 presents vapour pressure data for 21 compounds. The data were obtained by a critical evaluation of experimental results in the literature. The data available were limited but using a correlation previously developed for the alkanes that relates the second differential of the Wagner vapour pressure equation to the difference between the ideal gas and liquid heat capacities extrapolation was possible. The Wagner equation was used over a temperature range from close to the melting point to the critical point, although for some compounds the correlation was stopped at about 0.9 of the critical temperature. The coefficients of the equation are given and two tables of vapour pressure calculated using them are included; in SI units at 5 K intervals (although at low temperature a 10 K interval is used for the first four values) and in mm of mercury or atmospheres (for the higher values) at 5 degree Celsius intervals. A table also gives the saturation temperature at various specified pressures and indicates the possible uncertainty in the calculated values. An Antoine equation is given fitting the Wagner equation values between 2 and 200 kPa with an rms deviation of less than 0.05 per cent. The sources of data for each compound are also listed. Density data for the compounds (except 4-methylbiphenyl) appear in ESDU 94002, and the choice of critical point values gave the best correlations for both vapour pressure and density.