Predicting Flammability of Railcar Interior Finish With Small-Scale Heat Release Rate Data

There is interest in providing a heat release rate based flammability requirements for interior finish materials on railcars. As a result, a research study was performed to develop a simple empirical model that can predict the real scale fire performance of an interior finish material from ASTM E1354 cone calorimeter data. A simple to use model has been developed to predict whether a material will contribute significantly to the growth of a fire inside of a railcar. The model consists of a flammability parameter, defined as the difference between the average heat release rate and the ratio of the ignition time and the burn duration. As indicated by the model, the relative flammability of materials is based on the balance between the heat release rate and the ease of ignition relative to burning duration. This work is focused on the use of the model in predicting material fire growth performance in full scale NFPA 286 room/corner tests, which has not previously been performed. The empirical flammability model was developed to use parameters which were obtained from cone calorimeter tests at 50 kW/m² and provides a single value for a material. Generally, materials that have a flammability parameter of greater than 0.7 were determined to cause flashover in the NFPA 286 test, while those less than 0.6 did not cause flashover. The materials in the region between these values are borderline, with some causing flashover and some not. An initial assessment of a database of passenger railcar materials using the flammability parameter model revealed that about 50% of materials that meet NFPA 130 flammability requirements using ASTM E162 have the potential to cause flashover in the NFPA 286 room-corner test.