Samples of chemicals involved in the fire were obtained from product manufacturers. Potential reaction consequences were determined using A Method for Determining the Compatibility of Hazardous Wastes. Reactions with the greatest potential to produce heat or fire were selected for testing. Potential binary, tertiary, and synergistic heat of reaction tests were conducted.
Induction reaction periods were determined to ensure that adequate reaction times were employed. The order or sequence of chemical reactants was also varied to determine maximum heat generation. Initial tests were conducted in one liter glass reactors with a digital thermocouple equipped with an immersion probe. Reactions yielding the highest reaction temperatures were scaled up (8 liter glass reactors) to determine if heats of reaction were mass limiting. Results indicated that insufficient heats of reaction were produced to elevate temperatures above threshold autoignition temperatures (for wood and cardboard 400 to 500 oF).
The cause of the fire was determined not to be due to the autoignition of chemicals on the trailer. The most probable cause of the fire was the crushing of pressurized paint spay cans during a load shift and the release of propellants and ignition by an open flame such as sparks from railcar wheels.
A video tape of typical flatcar braking and spark generation was provided to Remtech for determination of spark temperature and projection distances. Still frame capture indicated that molten sparks released during braking had sufficient mass and projection to enter the nose of the trailer where propellants could be ignited.
Remtech's investigation and accident reconstruction shifted the responsibility of the fire cause away from the LTL and saved them an estimated $300,000.