Editor's Note: There's a lot of controversy now surrounding the West, Texas, explosion and it's cause. We explore the potential risks for problems with anhydrous ammonia below. Safety is always our greatest concern, and we felt this was information you needed to know. We'll keep you posted on issues related to the explosion as they arise in the coming weeks.
The recent explosion in West, Texas, has put anhydrous ammonia safety in the news, raising the question of whether the same catastrophe could happen on farms. The chemical compound, rich in nitrogen, is commonly used on farms to fertilizer crops.
John Nowatzki, ag machinery systems specialist with North Dakota State University, says anhydrous ammonia explosions are extremely rare because under normal conditions it takes temperatures of over 1500 degrees F for the gas to ignite. However, anhydrous ammonia tanks in fire are certainly a danger to explode.A bigger risk for farmers is exposure, which can lead to severe burning of skin, suffocation and death.
“As far as safety, farmers are always way more concerned about breathing it or getting it on their skin because of burning than they are about explosion,” he says.
Anhydrous comes from the Greek word that means “without water,” Nowatzki explains. If exposed to air, the gas instantly bonds to water such as that contained in skin.
“Liquid ammonia, on the other hand, is not stored under pressure,” he says, “and is less caustic to skin because it already has water in it, so it doesn’t have to gather that water molecule through the moisture in your skin.”
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Anhydrous ammonia is a clear, colorless gas that has a very characteristic odor, which is its biggest safety feature. It is used and stored under high pressures, and a sudden rupture can shoot ammonia 10 to 20 feet.
Most accidents with anhydrous ammonia are due to uncontrolled releases caused by faulty equipment or careless or untrained workers.
“That being said, explosion is still an important issue,” Nowatzki says. “Heat from accidental fires, whether building fires or field fires, would be enough to ignite the gas.” Using welding equipment on or near the storage tank can create the same flashpoint.
Protective equipment is required by law to be available where anhydrous ammonia is stored, handled, or applied. Wearing protective equipment greatly reduces the chance of injury.
Safety procedures must also be in place.
“Farmers have to be very careful not to weld on a closed container of any kind, including piping,” he says. “And, if you have an anhydrous ammonia tank that catches fire in the field, you want to make sure you don’t try to recover it. Just stay away.”
Nowatzki says use of anhydrous ammonia is declining on farms for different reasons. “One is that the chemical compound has been used illegally to make methamphetamines, and farmers are finding that nurse tanks left in field over night have been stolen, making them a hassle to protect.”
The other reason, he says, is that other forms of fertilizer, such as liquid nitrogen and urea, a granular, are becoming more cost competitive.
Read more about the safe use and handling of anhydrous in Nowatzki’s bulletin “Anhydrous Ammonia: Managing the risks.” http://www.ag.ndsu.edu/pubs/ageng/safety/ae1149.pdf