Cone calorimeter studies on fire behavior of polycarbonate glazing sheets

Polycarbonate glazing sheets used to be protected by a film. Earlier fire investigations cases suspected ignition of polycarbonate is due to igniting the protective film. Therefore, polycarbonate materials with and without a protective coating were tested by a cone calorimeter under radiative heat fluxes of 10 kWm-2 to 70 kWm-2. In addition to thermal properties, smoke toxicity upon burning the materials was also studied. Values of lethal toxic potency LC50 deduced by measuring only carbon monoxide will be discussed. The calculation procedure with a cone calorimeter is clarified. It is found that polycarbonate would not be ignited under flashover heat flux at floor level of 20 kWm2. However, the sample would be ignited and then burned when there is a protective film. Smoke emitted will be more toxic in having lower value of LC50. Results confirmed that materials protected by the coating film might have a higher fire risk. Finally, a three-dimensional risk diagram with three parameters x, y, and z on flashover propensity, total heat released per unit area, and LC50 are proposed for hazard assessment.