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Michael Fox, PhD.




Semi-Trailer Fire

The driver of a tandem semi-trailer noticed smoke coming from his front trailer and pulled into a rest area off a major interstate freeway. The driver and the co-driver inspected the trailer and found a dripping liquid that would stain the plastic mud flap. They also continued to notice small puffs of white gas or smoke coming from the trailer. They did not open the door to investigate but called their company to inform them of the situation. 

The trailer contained some hazardous materials and over 14,000 pounds of non-hazardous, but combustible, materials. The trucking company’s HAZMAT specialist advised the drivers to stay away from the trailer and clear the area, as there were toxic inhalation chemicals on board. A team of first responders was called from a major city about 40 miles away. 

Chemical fires and explosions- Semi-Trailer fire
The photo here shows the strength of the fire within a few minutes of the door being opened.

The local fire department showed up within about 10 minutes, but they were advised to wait for the first responders who did not arrive until about 90 minutes later. After the first responders arrived, they opened the trailer door and tested the pH of the leaking liquid and found it was very acidic (pH < 1). Shortly after they opened the trailer door they noticed a glow coming from the middle of the trailer and within a few minutes the trailer erupted into flames. There had obviously been a smoldering fire on board the trailer and when the door was opened and air was allowed in. The nature of the fire quickly shifted from smoldering to full blown fire. About that time the first responders allegedly turned to the fire fighters and said: “It’s your baby now.” 

An evacuation of the nearest residents was called almost immediately. The fire continued to burn from about 1 A.M. to about 10 A.M. The fire would frequently erupt after apparently being extinguished. At about 5 A.M. a police officer responded to an alarm at a nearby community college that was about a half mile directly downwind from the fire. He was only exposed to the combustion products of the fire for a brief time (less than a minute) before he was called to help with the evacuation of a hospital that was even further away from the fire than the college, but like the college, downwind of the now smoldering fire. 

Within two hours, the police officer was in the hospital emergency room being seen for an uncontrollable cough. With in a couple weeks he had to be hospitalized for a continuing respiratory problem and he eventually had to quit working as a police officer and was approved for social security disability. It was also noted that a dog that was left out and chained up during the first evacuation was found dead the next day. 

Chemaxx was hired to investigate the cause of the fire and to characterize the combustion products that might have been inhaled by the police officer at the community college. The Chemaxx opinion of the most likely cause of the fire was that a package of perchloric acid was breached by a load shift, which subsequently mingled with combustible materials. Perchloric acid is a strong oxidizer and is know to cause fires when mixed with combustibles. 

The scientific method as outlined in NFPA 921 was used to investigate the cause of the fire, while logical reasoning, intuitive methods and air dispersion models were used to assess the likely nature of the combustion products inhaled. DOT Regulations of 49 CFR were also important issues. Of particular concern was the DOT requirement for Emergency Response Information.

Dr. Fox is a fire expert, explosion expert and chemical expert with extensive experience in OSHA, EPA, and DOT chemical regulations and chemical safety.