Thermal behavior and toxic emissions of flame retarded timber in fire enclosure tests

Timber in different forms contributes as first and secondary ignited material to the initiation and spreading of fires in industrial buildings. The aim of this work is to investigate experimentally the fire behavior of wooden surfaces treated or not with flame retardants in a 1.57 m3 fire enclosure linked to the FTIR analyzer in well ventilated conditions (75kg/h) that are usually encountered in industrial activities when large metal doors, ramps, ventilation openings, etc are open in order to serve the process of production. In order to simulate the \“worst reasonable cases” of fire scenarios, wooden cribs have been constructed with complex geometry and configuration, and various quantities (grams) of ethanol were used as ignition sources. Seven (7) wooden crib fires were investigated using untreated pine wooden cribs or those treated at different percentages (%) of the total surface area with a water-based, flame retardant intumescent, suitable for internal surfaces. In most fully treated (100% F.R.) cases, even in a halftreated (50% F.R.) case, lower or almost equal to unity emissions were measured compared with the bare samples. This can be explained, in such cases, due to the fact that during the intumescent action there was either ‘no ignition’ of the samples (100% F.R.-treated cases), or a considerable ignition delay (50% F.R.- treated case). Excessive HCN and NOx occurred in 60% of untreated cases due to the considerable involvement of the flame retardant paint in flaming combustion, since it contains N in its chemical composition. It is proposed that the application of intumescent flame retardants on wooden surfaces located close to ignition sources in the most probable areas for a fire to break out, could be a safe and effective approach in reducing fire losses in industries. Keywords: wood, fire enclosure, flame retardant, heat release rate, ignition, FTIR analyzer, emissions.