What is Anhydrous Ammonia?

Anhydrous ammonia is a chemical made up of one part nitrogen (N) and three parts hydrogen (H). It is typically synthesized from the air using natural gas. Anhydrous ammonia (NH₃) is one of the most used sources of nitrogen for plant growth because of the attractive lower price when compared to other sources of nitrogen and readily availability. NH₃ is a hydroscopic compound, which means that it seeks water from the nearest source, including the human body. This attraction places eyes, skin and lungs at greatest risk because of their high moisture content.

Anhydrous ammonia has to be handled and stored under pressure, which requires specially designed and well-maintained equipment. To ensure operator safety, workers must be trained to handle this product and to follow strict work procedures.    

Anhydrous ammonia has a distinct odor, which humans can detect in concentrations as small as 5 parts per million (ppm). When used as fertilizer, NH₃ has concentration of about 1x10⁶ ppm. Brief exposure to concentrations of 2,500 ppm to 6,500 ppm can result in death.

Exposure

Exposure to NH₃ can happen suddenly and is almost always unexpected, including these situations:

·         During the transfer from the nurse tank to the applicator. NH₃ can escape from the transfer hose or valves that connect the hose to the nurse tank or applicator. Farm operators must always follow procedures for making and breaking connections because the fertilizer is under extreme pressure.

·         Equipment fails. Valves malfunction, causing NH₃ to be sprayed in any direction with a force greater than of a fire hydrant.

·         During transportation. A loose or broken hitch can cause anhydrous hose to simply pull apart. Always use safety chains and a locking pin hitch when transporting the nurse tank.

·         Filling tanks beyond recommended capacity.

Operator Protection and First Aid

The best first aid treatment for anhydrous ammonia exposure is water – lots of it. Flush all exposed areas with water for at least 15 minutes.

Face shield or goggles, rubber gloves and a heavy-duty, long-sleeved shirt are recommended as minimum protection for an operator routinely dealing with NH₃.

Regulations require that all farm vehicles used for NH₃ carry a container filled with at least five gallons of water. This water should be readily available for flushing the eyes and skin in case of exposure. Also carry a 16-oz. water bottle. It provides an immediate source of water in case of an accident.