The effectiveness and the failure mechanism of fire barriers in residential upholstered furniture were investigated by full-scale flaming tests on upholstered chair mock-ups. Six commercial fire barriers were tested in this study. Fire barriers were screened for (1) the presence of elements that are typically used in fire retardants and, (2) the presence of targeted fire retardants. For each fire barrier, triplicate flammability tests were run on chair mock-ups where polyurethane foam and polyester fiber fill were used as the padding materials, and each chair component was fully wrapped with the fire barrier of choice and a polypropylene cover fabric. The ignition source was an 18 kW square propane burner, impinging on the top surface of the seat cushion for 80 s. Results showed all six fire barriers reduced the peak heat release rate (as much as ≈ 64 %) and delayed its occurrence (up to ≈ 19 min) as compared to the control chair mock-ups. The heat release rate remained at a relatively low plateau level until liquid products (generated by either melting or pyrolysis of the padding material) percolated through the fire barrier at the bottom of the seat cushion and ignited, while the fire barrier was presumably intact. The flaming liquid products dripped and quickly formed a pool fire under the chair and the peak heat release rate occurred shortly thereafter. Ultimately, the ignition of the percolating liquid products at the bottom of the seat cushion was identified as the mechanism triggering the failure of the fire barrier.
Keywords: bench-scale; fire barrier; flammability; flexible polyurethane foam; full-scale; residential upholstered furniture.