UC San Diego

Experimental tests were conducted on a single cartoned, unexpanded Group A plastic commodity to evaluate an approach to commodity classification in complex fuel geometries. The approach is based on comparing the chemical energy released during the combustion process with the energy required to vaporize the fuel. The ratio of these two quantities is often called the mass transfer number, B-number or Spalding number. The Group A commodity tested was essentially a three-dimensional cardboard box subdivided by cardboard placeholders for individual unexpanded polystyrene cups. Experiments consisted of burning the front face of a single box with all remaining faces uniformly insulated. Measurements of gas temperatures, mass-loss rate and heat flux from the flame were used to calculate a modified B-number, which includes consideration of the role of radiant heat transfer. Results from experiments have produced time-averaged B- numbers for stages of burning. Comparison to a concurrent study using a cone calorimeter on smaller-scale material samples shows good agreement between these methods. Future use of the results to improve commodity classification for better assessment of fire danger is discussed