Predicting the emission rate of volatile organic compounds from vinyl flooring

A model for predicting the rate at which a volatile organic compound (VOC) is emitted from a diffusion-controlled material is validated for three contaminants (n-pentadecane, n-tetradecane, and phenol) found in vinyl flooring (VF). Model parameters are the initial VOC concentration in the material phase (C0), the material/air partition coefficient (K), and the material-phase diffusion coefficient (D). The model was verified by comparing predicted gas-phase concentrations to data obtained during small-scale chamber tests and by comparing predicted material-phase concentrations to those measured at the conclusion of the chamber tests. Chamber tests were conducted with the VF placed top-side-up and bottom-side-up. With the exception of phenol and within the limits of experimental precision, the mass of VOCs recovered in the gas-phase balances the mass emitted from the material phase. The model parameters (C0, K, and D) were measured using procedures completely independent of the chamber test. Gas- and material-phase predictions compare well to the bottom-side-up chamber data. The lower emission rates for the top-side-up orientation may be explained by the presence of a low-permeability surface layer. The sink effect of the stainless steel chamber surface was shown to be negligible.