A practical method for the estimation of ambient vaporization rates of compounds

A practical method for the estimation of ambient vaporization rates of a diverse set of organic compounds is presented. The method utilizes thermogravimetric analysis (TGA) to measure the vaporization rates of solids and liquids at elevated temperatures and reduced pressures. The rates are correlated with functions of temperature and pressure using multiple linear regression. The empirical equation generated for each compound is used to estimate its vaporization rate at ambient temperature and pressure. Good agreement was found between predicted and measured values. Samples (with vapor pressures that range between 10^-5 Pa and 10¹ Pa) are exposed to both stagnant air and to a 60 cm/sec (1.3 mph) air flow in order to determine the usefulness of the method when vaporization is influenced by convective air flow. The 60 cm/sec air flow produced a similar increase in the vaporization rates of all of the compounds, indicating that a simple proportionality constant can be employed to adjust estimated evaporation rates for air flow velocity.