What is anhydrous ammonia?

Anhydrous ammonia, also known as NH3, is a dangerously volatile condensed chemical that can be explosive/flammable in certain circumstances. It is classified as an extremely hazardous material by the NFPA hazard diamond and regarded as the following:

  • Health Hazard (Blue) – 3
  • Flammability (Red) – 1
  • Reactivity (Yellow) – 0

To fully understand what anhydrous ammonia is, we must look at the definition of the word “Anhydrous.” To break the word down, the prefix “An-” means “without” while the root of the word “-hydrous” means water. Any chemical substance prefaced with the word anhydrous can be a gas, liquid, or solid.

The potential health hazards

Anhydrous ammonia boils at -33.34 degrees Celsius or -24.01 degrees Fahrenheit, which is why it is extremely important that the pressurized tanks be treated with caution. If the tank is punctured the anhydrous ammonia suddenly begins to boil, emitting a cloud of toxic vapors known to cause serious damage to the skin, eyes, lungs, and even death.

When anhydrous ammonia comes into contact with any part of the body that holds moisture, the chemical turns into ammonium hydroxide which instantly results in chemical burns. Living tissue becomes dehydrated while the cells that have been exposed are immediately killed by the toxic compound. Exposure often leaves the victim with disfigurement of the skin as it is reduced to a sticky and gelled substance that will need to be cut away to heal properly. It may also cause blindness. As for respiratory exposure, first-response rescue workers might only be able to help by administering oxygen. Even then, the respiratory system might go into paralysis due to difficulty breathing.

What do I do if exposed?

If exposed to anhydrous ammonia, the affected area should be rinsed with water and all affected clothing must be removed unless frozen to the victim’s skin. Do not stop rinsing until the victim is safely transported to medical treatment or at least for fifteen minutes as anhydrous ammonium has such an affinity to water that it takes gallons to dilute the chemical. It will continue to burn the victim as long as it exists on their person.

How to prevent accidents

If a job requires its workers to complete a task involving anhydrous ammonia, the proper PPE equipment must be used. This includes:

  • Chemical protective gloves including a long-sleeved shirt
  • Ventless goggles or full-face shield
  • It is recommended that the worker not use contact lenses as ammonia may become trapped underneath if exposed
  • A chemical apron or even a respirator mask could also be helpful depending on how the material is being handled

The best way to prevent injury is to train the employees in the correct procedure appropriate for the environment in which anhydrous ammonia is being handled. Prevention is also linked to complying with laws regarding the transportation of hazardous materials. These rules and regulations are explained in CFR title 49.

Proper ammonia pipe labeling is also one more step closer to eliminating serious work injuries and even death. There are numerous resources available on proper pipe and container labeling for dangerous chemicals like ammonia as well as a HazCom guide for transporting this material. If hazard labeling is a constant project at your workplace, industrial printers can quickly and easily print code-compliant labels in-house.


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