Thermal behavior and Toxic Emissions of Flame Retarded Timber in Cone Calorimeter Tests

Abstract

The thermal behavior and toxic emissions of timber products common in industrial buildings in Northern Greece treated or not with flame retardants are investigated. Eight species of wood treated or not with three typical intumescent flame retardants were subjected to constant incident heat fluxes of 35, 50, 65 and 80 kW/m2 in a cone calorimeter linked to the FTIr analyzer. The test results presented in this paper cover the following characteristics: (i) time to ignition, (ii) heat release rate (hrr), (iii) average (300 s) hrr, (iv) effective heat of combustion (mJ/kg), (v) smoke production and (vi) toxic species emissions. The main findings of the experimental analysis are that under the influence of the flame retardants: there was either ‘no ignition’ of the samples or a considerable ignition delay (at lower irradiances) compared with untreated samples. Thermal emissions significantly decrease in terms of the values of ‘peak hrr’ and ‘First 300 s mean hrr’ (by a factor varied from 2 to 5 up to type flame retardant used). In the cases of flame retarded samples, where there was ‘no ignition’ or a considerable ignition delay of the samples there were similar or less toxic emissions compared with the bare samples. Nh 3 was an exception, since both flame retardants contained ammonium in their chemical composition, which was released during the intumescent action of the samples. based on the results of this study, the application of intumescent flame retardants on wooden surfaces is proposed for the cases where ‘no ignition’ or considerable ignition delay occurred. This could be a safe and cost effective approach in reducing fire losses in industrial buildings.