Fire toxicity of aircraft seat covers and seat foam

A cone calorimeter with air supply box around the fire test zone was shown to reproduce all the classic features of compartment fires and hence could provide a basis for the determination of toxic gases emitted from materials in fires, under realistic test conditions. Direct hot exhaust gas sampling was used from a small chimney attached to the cone heater outlet and heated sample lines, pumps and filters were used to transport the sample to a heated Temet FTIR, calibrated for all the toxic gases of interest in fire toxicity. Three aircraft seat material were tested, two seat covers of fabric and leather and the seat foam. All the materials were from commercial suppliers to the aircraft industry. Ventilation conditions in the fires were typical of those on aircraft at 9-15 ACH. All three material samples had S and N in their composition, the S from the fire retardants and N from the use of an acrylic fibre in the seat covers and of PUF in the seat foam. As a consequence SO₂ and HCN were major toxic species in all the material fires. In all the fires HF was detected and for the foam and the leather seat cover HCl was detected and these indicate the presence of halogen based fire retardants in the material composition. Thus, most of the toxic gases measured were due to the presence of S, N, F and Cl in the material composition. Other toxic gases detected were the more conventional fire toxic gases CO, formaldehyde, acrolein and benzene. Only in the fabric fire was NO₂ significant. The peak toxicity occurred in the initial flaming combustion and the toxicity order was leather > fabric > foam on both an LC₅₀ and COSHH15min toxic assessment basis. Both toxic assessment methods showed the same group of toxic gases were important and only their relative importance changed between the toxic assessment methods. It was concluded that toxic gas assessment should be added to current material test programmes on fire behavior and that the cone calorimeter, modified as in the present work, was a good basis for the toxic gas measurements.