It is being said that the fatal explosion that killed a 35-year-old battalion chief while operating at a tractor-trailer fire was a “smoke explosion.” The investigation continues, looking at other fuel sources, such as the foam insulation in the trailer. They have ruled out a BLEVE. A sample of rigid foam insulation from the trailer was provided for testing to identify the foam type and its potential as a fuel source for the smoke explosion. The refrigerated intermodal container had a portable generator, or genset, affixed to the bulkhead of the container. The genset in this incident ran on diesel fuel and included a self-contained diesel fuel tank on the lower portion of the genset device. Based on the information provided by the UL Research Institutes team, a visual inspection of the diesel tank did not reveal any evidence of bulging or rupture. The container was loaded with frozen chicken.