The Use of Small Scale Fire Test Data for the Hazard Assessment of Bulk Materials

Abstract

An experimental study of fire testing of solid materials has been carried out to investigate whether or not these tests yield useful data for the burning of materials stored in bulk, for example in warehouses. Tests were performed using the Cone Calorimeter, the HSE third scale room/corridor rig, BS 5852 part 2, and some nonstandard tests. The results have been compared and the problems with fire testing have been discussed with reference to the current literature and trends in fire testing. The additional complications of unusual material behaviour under exposure to heating have also been investigated. In the third scale room/corridor test, where vertical, parallel samples are used, the separation distance between the samples was found to play a significant part in whether ignition of fire retarded samples could be achieved or not. A literature survey revealed a dearth of information on this subject. As this type of parallel configuration is found in warehouse storage as well as vertical ducts and cavities, an investigation was conducted into flames between vertical parallel walls. Measurements were made of total and radiative heat fluxes at the walls, flame and gas temperatures, and flame heights under a variety of conditions. It was found that the configuration of the system was very important, with the separation distance and fluid dynamics both having a major influence. Burner position, geometry and heat release rate were also varied and their influence assessed. Statistical methods were employed to correlate the heat flux data and temperatures with the other variables, with excellent correlation coefficients for the equations developed. These have been compared with previous expressions developed for flames against vertical walls. Results from CFD work on two of the parallel wall cases of special interest were analysed and discussed with reference to the . experimental results. The findings have implications for the fire testing of materials, and for the hazard assessment of materials stored in high rack storage. An understanding of potential exposure conditions in a real fire scenario are essential for the appropriate use of fire tests.