While an inexpensive and effective source of nitrogen for growers, anhydrous ammonia can pose serious health and safety risks if not handled properly.

Common Exposures

Exposure to anhydrous ammonia can happen suddenly and is almost always unexpected. These are some common scenarios for exposure:

  • During its transfer from the nurse tank to the applicator. Anhydrous ammonia 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.

  • When equipment fails. Malfunctions of valves, the quick coupler that connects the nurse tank to toolbar and gauges cause dangerous situations that could spray anhydrous ammonia in any direction with a force greater than that of a fire hydrant. Hoses exposed to sunlight, constant rubbing or those that are stretched are subject to failure.

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

Types of Injuries

Anhydrous ammonia is a hydroscopic compound, which means that it seeks water from the nearest source, including the human body. This attraction places the eyes, lungs and skin at greatest risk because of their high moisture content. Caustic burns result when the anhy¬drous ammonia dissolves into body tissue.

Most deaths from anhydrous ammonia are caused by severe damage to the throat and lungs from a direct blast to the face. When large amounts are inhaled, the throat swells shut and victims suffocate. Exposure to vapors or liquid also can cause blindness.

An additional concern is the low boiling point of anhydrous ammonia. The chemical freezes on contact at room temperature. It will cause burns similar to, but more severe than, those caused by dry ice.

Under normal temperature and air pressure, anhydrous ammonia is a colorless gas. However, anhydrous ammonia is used and transported under pressure as a liquid. All equipment used for applying or transferring liquid anhydrous ammonia must be designed for use under high pressure to avoid ruptures or breaks.

Reducing Risk

You can reduce your risk of exposure and injuries in these ways:

  • Always keep 5 gallons of clean water in your supply tank and carry a small squeeze bottle to clean any spills.

  • Understand first aid treatment and practice what you would do in an emergency.

  • Wear ventless goggles, rubber gloves and a long-sleeved shirt when working with anhydrous ammonia.

  • Regularly inspect equipment and have worn hoses and valves replaced.

  • Never allow bystanders in the area where anhydrous ammonia is being transferred or applied.

  • Review instructions before coupling and uncoupling lines.

Taken from “Play it safe with anhydrous ammonia”, an Iowa State Univ. Extension publication.   << Back to Issue Homepage