Posted on 26/10/2023 in Transport Fire Safety 2023
Tests show fire danger of materials in buses

Bus seat, floor and interior trim materials as used in buses and coaches were tested for fire behaviour and smoke emission, concluding that they “lead to very limited times for escape and rescue in case of fire in a bus cabin”. Materials tested, supplied by manufacturers, were as used in public and commercial buses and coaches: four textiles and a polyurethane foam*. Cone calorimeter, FTIR (Fourier-transform infrared spectroscopy) and DIN tube furnace tests analysed heat release, smoke release and toxic gases, including carbon monoxide, HCN (hydrogen cyanamide), acrolein, SO2, HF, acetylene, formaldehyde, ammonia … Results show high heat release and smoke emission within five minutes, with IDLH (Immediately Dangerous to Life and Health) values exceeded for all materials, in particular for HCN. Polyurethane foam shows the highest heat release of materials tested and polyester textile the highest total smoke production. PUR shows acrolein 130x higher than IDLH. The authors conclude that, despite all materials tested fulfilling the most recent regulatory requirements for bus interiors (UNECE R 118 Annex B, see pinfa Newsletter n°64), results are not significantly better than previous tests (Hofmann et al. 2014). They recommend that to improve bus passenger safety, heat release, smoke production and smoke toxicity requirements should be introduced for bus interior materials, for example those already applicable for railways in Europe (EN 45545-2).

* Textiles: RC 70% polyester 30% wool, CD = 65% polyester 28% wool 6% viscose, MB = 100% polyester, LW = polyester/polyamide. PUR Green = green-coloured polyurethane foam.

“Reaction-to-fire testing of bus interior materials: Assessing burning behaviour and smoke gas toxicity”, Fire and Materials. 2023;47:665–680

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