A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Fire and flammability
Several authors published heat release rate data for plastic and resins but attempts to correlate these data with performance in standard flammability tests have proven largely unsuccesful. The heat release rate at zero external heat flux (intrinsic heat release rate/ HRR0) ist postulated to be the material fire response govering ignition resistance in flammability tests.The intrinsic heat release rate HRR0 can be measured directly in unforced flaming combustion or obtained by extrapolation to zero heat flux in forced flaming combustion. Both methods are in reasonable (qualitative) agreement for several polymers considering that the polymers were commerial products from different sources. Ignition resistance or self extinguishing behavior in isolated flame (flammability) tests is observed if the intrinsic heat release rate of the material is below a critical value HRR0 = 100 +- 25 kW/m2 as measured in a cone calorimeter. Thus, a critical heat release rate at incipient burning is a physically-based flammability criterion that relates UL 94 results and LOI to fire calorimetry data obtained in a standard test configuration. The steady state burning model shows that the intrinsic heat release rate is proportional to the heat release parameter and the difference between the flame heat flux to the surface and the heat losses from the surface by reradiation and conduction. Because these three terms contribute to the intrinsic heat release rate as the difference between two large numbers the intrinsic heat release rate can change in both sign and magnitude over a relatively narrow range of material properties, composition, or external conditions (e.g., oxygen concentration) consistent with the manifestation of a critical phenomenon. Thus, an abrupt transition from self propagating to self extinguishing behavior in isolated flame tests is impareted by small modifications to the material composition or combustion atmosphere that have relatively little impact on fire behavior.
Fire and flammability
Several authors published heat release rate data for plastic and resins but attempts to correlate these data with performance in standard flammability tests have proven largely unsuccesful. The heat release rate at zero external heat flux (intrinsic heat release rate/ HRR0) ist postulated to be the material fire response govering ignition resistance in flammability tests.The intrinsic heat release rate HRR0 can be measured directly in unforced flaming combustion or obtained by extrapolation to zero heat flux in forced flaming combustion. Both methods are in reasonable (qualitative) agreement for several polymers considering that the polymers were commerial products from different sources. Ignition resistance or self extinguishing behavior in isolated flame (flammability) tests is observed if the intrinsic heat release rate of the material is below a critical value HRR0 = 100 +- 25 kW/m2 as measured in a cone calorimeter. Thus, a critical heat release rate at incipient burning is a physically-based flammability criterion that relates UL 94 results and LOI to fire calorimetry data obtained in a standard test configuration. The steady state burning model shows that the intrinsic heat release rate is proportional to the heat release parameter and the difference between the flame heat flux to the surface and the heat losses from the surface by reradiation and conduction. Because these three terms contribute to the intrinsic heat release rate as the difference between two large numbers the intrinsic heat release rate can change in both sign and magnitude over a relatively narrow range of material properties, composition, or external conditions (e.g., oxygen concentration) consistent with the manifestation of a critical phenomenon. Thus, an abrupt transition from self propagating to self extinguishing behavior in isolated flame tests is impareted by small modifications to the material composition or combustion atmosphere that have relatively little impact on fire behavior.
Fire and flammability
Feuer und Brennbarkeit
Lyon, R.E. (author) / Hughes, W.J. (author)
2003
12 Seiten, 8 Bilder, 2 Tabellen, 22 Quellen
Conference paper
English
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