Hazmat: Understanding Ammonium Nitrate

mmonium nitrate fertilizer, chemically classified as an oxidizer, is commonly used in agriculture and for commercial and residential turf grass. Approximately 7 million tons of ammonium nitrate are produced annually in the U.S. and, under normal...


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Deadly explosions

Several major disasters involving ammonium nitrate have occurred over the years. In Texas City, TX, on April 16, 1947, the SS Grandcamp was at the port taking on a load of ammonium nitrate fertilizer to be shipped to Europe as part of the rebuilding process following World War II. Approximately 17 million pounds of ammonium nitrate was loaded onto the ship. Also in the harbor that day was the SS High Flyer, located approximately 600 feet from the Grandcamp on the same dock and loaded with 2 million pounds of ammonium nitrate. (By comparison, the bomb used in the terrorist bombing of the Murrah Federal Building in Oklahoma City, OK, in 1995 contained 5,000 pounds of ammonium nitrate. The deadly explosion at West, TX, this year involved approximately 60,000 pounds of ammonium nitrate.)

At 9:12 A.M., an explosion occurred within the hold of the Grandcamp. Instantly, all 27 members of the Texas City Volunteer Fire Department at the scene were killed. Some bodies were disintegrated by the heat and blast pressure of the explosion. All that remained of the department’s fire apparatus were piles of twisted metal. Texas City lost all but one of its firefighters and all of their apparatus in the explosion. (For more information about the Texas City disaster, see “The Day Texas City Lost Its Fire Department” by Robert Burke in the May 2007 issue of Firehouse®.)

On Nov. 29, 1988, at approximately 3:40 A.M., the Kansas City, MO, Fire Department received a call for a fire at a highway construction site. Several explosions occurred following the arrival of the fire department. It was reported by the fire department that the first explosion involved a split load of materials in a trailer/magazine.

One compartment held approximately 3,500 pounds of ANFO. The rest of the contents were approximately 17,000 pounds of ammonium nitrate/fuel oil mixture with 5% aluminum pellets. In the second trailer/magazine there were approximately 1,000 30-pound “socks” of ammonium nitrate/fuel oil mixture with 5% aluminum pellets. Pumper 30 was dispatched and arrived on scene at 03:52. Twenty-two minutes after Pumper 41 arrived and approximately 16 minutes after Pumper 30 arrived, the magazine exploded, killing all six firefighters assigned to Pumper 41 and Pumper 30.

The 1995 terrorist bombing at the Oklahoma City federal building involved a homemade mixture of ammonium nitrate fertilizer and fuel oil. As a result of the attack, 168 people, many of them children, died and another 600 were injured.

No emergency responders were killed at either incident since the explosions occurred before their arrival, but that may not always be the case. More than 800 buildings sustained some type of damage from ground shock and blast pressure. Of the buildings damaged, 50 would have to be demolished. Windows were broken as far as two miles from the blast site and the blast was heard 50 miles away. It registered 3.5 on the open-ended Richter Scale in Denver, CO.

Next: The West, TX, tragedy n