Standard Room Fire Test Research at the National Bureau of Standards
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Research results with the proposed ASTM standard room fire test for interior finish materials are presented. The materials selected for the study were two untreated plywoods, a fire-retarded plywood, polystyrene foam, polyisocyanurate foam, and gypsum board. Three 900 s duration test scenarios were considered. Scenario A is a constant 180 kW ignition source exposure. Scenario B achieves the same maximum exposure after three intervals of 30 s each in which the heat release rate is increased in equal steps of 45 kW. Scenario C evaluates a material over a 300 s exposure at a nominal 45 kW, with another 300 s exposure at 180 kW, followed by 300 s at zero exposure. This zero exposure allows the material to be screened for continuation of burning afterwards. The study demonstrated that all three scenarios could adequately differentiate material fire behavior, in terms of the maximum degree of fire buildup attained and the time to reach the maximum, for the materials selected. However 1 scenario C would allow a more comprehensive evaluation of materials. Thermal radiation incident on the floor and room and doorway air temperatures were found to be suitable parameters for determining room fire buildup including room flashover. Surface flame spread and rate of heat release are discussed for the room fires. Unit area bench-scale rate of heat release data from the cone calorimeter may be predictive of the full-scale data when melting and dripping (which changes the active burning area) or very slow to ignite fire retarded materials (whose retardants may be baked out) are not involved. Further full-scale testing is desirable to establish more confidence and delineate the limits of validity.