NH3, (that’s the molecular symbol of anhydrous ammonia) is dangerous. But not the way some people think.
After the big fertilizer plant explosion in West, Tex., early reports blamed anhydrous ammonia for the blast. That’s not what happened. Anhydrous ammonia can cause freeze and chemical burns, but it isn’t normally explosive. It will only ignite as a vapor with exactly the right fuel to air mixture at a little over 1200 degrees F.
Because anhydrous ammonia is normally stored outside in heavy tanks like those used for propane, the chances of that happening are slim.
Plain old dust in a grain elevator is a greater explosion risk than NH3.
The reason we have NH3 is because at a concentration of 82%, it’s a very good source of nitrogen. Farmers inject the ammonia directly into the soil where plant roots can pick it up.
[imgcontainer][img:spread.jpg][source]rohnerlee[/source]A farmer injects anhydrous ammonia into a field. The chemical fertilizer can be dangerous, but it’s generally not explosive. That’s ammonium nitrate. Click photo to play video.[/imgcontainer]
With a boiling point of minus 28F, when NH3 is released into the atmosphere it vaporizes almost instantly.. That evaporation causes it to become colder than minus 50 F.
I have frozen my fingertips just undoing hose couplings between the nurse tank and my ammonia applicator. It gets cold. That’s why packing plants and other businesses with large refrigerated warehouses use anhydrous ammonia in place of freon in the their refrigeration systems.
During fertilizer time my hands chap and dry out just being around the fumes, no matter how much hand lotion I use. It’s dangerous for sure. Just a tiny whiff up the nose steals your breath. It burns lungs and eyes, and if a malfunction on the applicator or tank sets gas free, it can be scary or worse. It’s impossible to breathe or even see while engulfed in a vapor cloud unless wind carries it away or you’re able run clear.
The good news is the gas dissipates quickly in the wind. Without wind it can lay on the ground in a choking fog. Contact with liquid ammonia before it evaporates both burns and freezes unprotected body parts. NH3 is quickly absorbed into water or human flesh. Farmers keep water tanks on fertilizer applicators and near NH3 tanks at pumping stations, so anyone who comes into contact with it can wash it off.
One early news report out of Texas said anhydrous ammonia combined with water may have caused the explosion. That’s wrong. NH3 does not explode when combined with water and there’s no way water could have penetrated the heavy steel tanks it was in. If the ammonia had been set free from the tanks it would have vaporized instantly. In that case, water would have helped knock down the gas.
About the only blast I’ve heard caused by ammonia was the public relations explosion about McDonalds using hamburger treated with it.
But fertilizer can be dangerous stuff. While anhydrous ammonia’s worst qualities–possible suffocation or burns– are dangerous, they aren’t explosive in the truest sense. That’s not the case with ammonium nitrate because that product was developed as an explosive and later adopted by the fertilizer business.
[imgcontainer][img:leak1.jpg][source]keithtrimm.com[/source]Firefighters contain an anhydrous ammonia leak in Harbine, Neb., in 2011. [/imgcontainer]
That adaptation of nitrate probably came from chemical industry that found itself tooled up for war in peace time. (Our government also used anhydrous ammonia to harden dirt runways during World War II.) Suddenly the product switched from weapon to plant food. Farmers adopted the practice of using chemical fertilizer because it was cheap and added yield to crops like corn, wheat and cotton. With smaller sized farms of the 1940s and ’50s, average farmers used fertilizer in much smaller amounts than we do today. Dad’s early experiments with farm chemicals took him to Main Street and the local pharmacy for pesticides. He told me that’s also where his first keg of ammonium nitrate came from.
Farmers who used a few pounds of nitrate or non-explosive urea saw crops and pasture turn green and lush. A few pounds of chemical nitrogen later became a few tons. Using it replaced crop rotations, where nitrogen-fixing plants were grown followed by nitrogen dependent crops.
[imgcontainer right][img:blast2.jpg][source]ktbs.com[/source]Authorities say the explosion in West was likely caused by ammonium nitrate, a chemical created as an explosive and later adapted for use in agriculture.[/imgcontainer]
Farms grew in size, so individual farmers used more. If a little was good, a lot was better.
Seed and feed stores became seed, feed and chemical. As diversified livestock/grain farms have been replaced by livestock aggregators like Cargill, Smithfield and Tyson, feed is no longer mainstay farm supply merchandise just as livestock is no longer in the mix on individual farms.
In 1955 the little town where I went to school had three feed stores when I entered first grade. Today there is none.
Flammable wood is the construction material of choice for fertilizer plants because of the corrosive nature of fertilizer. Cellulose holds up better than metal frameworks and siding. Plastic and vinyl are used more these days. But those materials can be more flammable than wood.
There’s been a lot of talk about the way Texas regulates businesses. Their lack of a fire code has been pointed out as a possible culprit for the fire and fertilizer plant explosion that decimated the town of West. Not much has been said about liability and insurance costs. Many times those things, the high cost of replacing lost inventory and assets, and a nervous lender wanting to protect collateral probably have more to do with the way dangerous products are stored than state regulation.
Another fact is that occasionally people just get careless and need a refresher course in what can go wrong. And sometimes accidents aren’t accidents at all. That’s what happened in Kansas City in 1988, when explosives grade ammonium nitrate stored at a construction site was ignited by an arsonist. Six firemen died in that blast.
Farming has evolved into something highly specialized and dependent on things farmers can’t grow for themselves. Early on, the local farm supply feed warehouse was piled high with a few tons of fertilizer in a building to the side.
In today’s modern corn-belt farm community, it may be hard to find feed, but fertilizer is always handy. Huge warehouses have been built dedicated to holding nitrogen, phosphorous and potash — and other mainstays like genetically modified seeds and pesticides.
Those and other things are what modern agriculture demands. In some towns like mine, the number of risks and people exposed to them are relatively small.
But as agriculture becomes more concentrated and uses more chemicals, the amount of those chemical stored in one spot will get more concentrated, too. Personal injury liability can be huge. That’s one reason why new modern fertilizer plants sit on isolated lonely spots outside of town.
It’s just good business.
Richard Oswald, a fifth generation farmer, lives in Langdon, Missouri, and is president of the Missouri Farmers Union.
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