The subject of a recent hearing before the Texas House Homeland Security and Public Safety Committee was the deadly explosion at the West Fertilizer Company that occurred in West, Texas on April 17th of this year. Ammonium nitrate was involved in the explosion that killed more than a dozen people, injured more than 160 and damaged or destroyed more than 150 structures.
One of the people to testify before the committee, Texas State Fire Marshal Chris Connealy, presented a briefing called Ammonium Nitrate Estimated Blast Effects. This report was prepared by Aristatek Inc. for the Williamson County Hazmat Team. The team, as well as the state, wanted a method of predicting damage with different quantities of the substance for estimating the potential dangers were it to explode.
Aristatek's brief includes a blast effects table for ammonium nitrate quantities from one ton to 300 tons. It was prepared using a combination of the company’s hazardous materials response software, PEAC-WMD, and its own in-house chemists and engineers. Aristatek is making the brief available to qualified emergency planning, response and zoning officials through the company’s web site. Information about the brief can be found here. . .
The ammonium nitrate brief should provide a resource for communities with local ammonium nitrate stockpiles to help them understand the possible consequences of storing or shipping this substance. The briefing includes an explosion calculator for open-air explosions which shows the distance that fragmentation will be thrown and calculates overpressure - blast effects that can knock down structures and severely injure individuals
According to Aristatek, “The algorithms were developed for TNT,” but Aristatek’s software “can compute the TNT equivalent of a substance.”
Emergency Film Group’s program, Inorganic Oxidizers studies response actions for incidents involving ammonium nitrate as well as two other important oxidizers, nitric acid and calcium hypochlorite. To learn more, read here. . .
Response to ammonium nitrate incidents is also covered in Responding to Highway Incidents Involving Commercial Explosives, created for the Institute of Makers of Explosives by Emergency Film Group.