Fires and Explosions

The investigation of fires and explosions involves some unique aspects not present in other accident investigations. The damage from these events is often widespread and the evidence available is changed in form and appearance by the effects of extreme heat, combustion, and pressure. An experienced investigator needs the skills of both a detective and a scientist to determine the cause of the fire or explosion. Often, the most difficult part is simply determining whether a given piece of evidence was burned as a result of the fire or was the cause of the fire. Many times, this question is also the key issue in the investigation.

Investigating even a seemingly small event with localized damage can require the assistance of varied disciplines such as material science, chemistry, thermodynamics, psychology, and electrical engineering. Principia's engineers have extensive background in these areas including formal training and certification in fire investigation by the California State Fire Marshall's Office. We also maintain a laboratory for conducting both burn and explosive testing.

The examples below serve to illustrate the wide variety of projects we handle in this field and some of the tools we use to solve these problems.

	Nationally, a disproportionately high number of fires are attributed to electrical causes. Much of this stems from a lack of understanding of the principles of electricity. In this example, this fire-damaged electrical outlet box was determined by the fire department's investigator to be the cause of a fire that destroyed multiple structures and property. We were able to use metallurgy and knowledge of the behavior of electrical wiring subjected to fire to demonstrate that this box and its wiring was not the cause of the fire. In spite of evident non-code wiring in the box, we showed that all the damage visible to the wires and other hardware was caused as result of the heat of the fire.
	This electric grill was implicated in a fire that destroyed a rural town's industrial district. We placed thermocouples on an exemplar grill to record the temperatures at various points on the grill. The results of our test showed that the grill could not have caused the fire.
	A single-vehicle tractor-trailer accident caused the diesel tanks to rupture and separate from the vehicle. The resulting fire consumed much of the vehicle and its systems. We used fire modeling to calculate the spread of fluids and fire at the scene in order to determine the likely sequence of events leading to the rupture of the tank. We determined that the rupture of the tank was not the likely cause of the fire. Instead, the fire started with other combustables and spread to the separated tank.