UN 1005 — Ammonia, anhydrous
Placard: Non-Flammable Gas. ERG Guide 125. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
Ammonia, anhydrous, is a colorless gas with a pungent, suffocating odor, widely used in industrial processes such as the production of fertilizers, plastics, and pharmaceuticals. As a DOT Class 2 gas, it poses significant hazards to first responders due to its toxicity and reactivity. With millions of tons transported annually, the risk of accidents and spills is ever-present. First responders may encounter ammonia in various settings, including industrial sites, transportation accidents, and agricultural areas. The scale of production and transport of ammonia is substantial, with the United States alone producing over 10 million tons per year.
Hazard overview: Ammonia is extremely hazardous, with vapors that are toxic and corrosive, causing severe eye and respiratory irritation. Prolonged exposure can be fatal, with an IDLH of 300 ppm. The gas is also highly soluble in water, forming a caustic ammonium hydroxide solution that can cause burns and severe injury. In the event of a fire, ammonia will produce irritating, corrosive, and toxic gases, exacerbating the hazard. The worst-case scenario for first responders is a large-scale spill or leak, requiring immediate evacuation and specialized PPE to prevent severe injury or death.
Response guidance: In the event of an ammonia spill or leak, first responders should isolate the area, with a small spill requiring a 100m isolation zone and a large spill requiring an 800m initial isolation zone, with downwind evacuation of 3.2km during the day or 7.0km at night. The correct suppression agent is water fog or spray for vapor knockdown, with dry chemical or CO2 for small fires. Decontamination is crucial, and CHEMTREC should be contacted for assistance. Evacuation zones should be established, and positive pressure SCBA and chemical-resistant suits are mandatory due to the severe eye and respiratory hazard.
Firefighter training notes: First responders should be trained to recognize the hazards of ammonia and take immediate action to isolate the area and evacuate personnel. A common tactical error is underestimating the severity of the hazard, leading to inadequate PPE and decontamination procedures. ICS positions, such as the Incident Commander and Safety Officer, should be aware of the hazards and take steps to mitigate them. Mutual aid criteria should include the availability of specialized PPE and decontamination equipment.
Regulatory context: Ammonia is classified as a DOT Class 2 gas, with a packing group of II. The OSHA PEL for ammonia is 25 ppm, and the TLV is 18 ppm. Ammonia is also listed on the CERCLA list, requiring specialized reporting and response procedures in the event of a spill or leak.
Storage & handling: Ammonia should be stored in a well-ventilated area, away from incompatible materials such as chlorine and bromine. The temperature limit for storage is -33C (-28F), and the container should be designed to withstand the pressure and corrosion potential of the gas. Top 3 incompatible materials for ammonia include chlorine, bromine, and iodine, which can react violently with the gas.
UN 1005 Quick Details
Common Hazards of UN 1005
- TOXIC and/or CORROSIVE; may be fatal if inhaled, ingested or absorbed through skin.
- Vapors are extremely irritating and corrosive.
- Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
- Fire will produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or dilution water may cause environmental contamination.
- Some may burn but none ignite readily.
- Vapors from liquefied gas are initially heavier than air and spread along ground.
- Some of these materials may react violently with water.
Chemical Identity & Physical Properties
Ammonia is a colorless gas with a pungent, suffocating odor, shipped as a liquefied compressed gas. It has a boiling point of -33C (-28F) and a vapor density of 0.6, making it lighter than air. The gas is highly soluble in water, forming a caustic ammonium hydroxide solution that can cause burns and severe injury.
| Also known as | Anhydrous ammoniaLiquid ammoniaAmmonia gasR-717NH3 |
| CAS Number | 7664-41-7 |
| Appearance | Colorless gas with a pungent, suffocating odor. Shipped as a liquefied compressed gas. Lighter than air as a gas, but vapors from liquid may initially hug the ground. |
| Flash Point | Not applicable (gas) |
| Boiling Point | -33C (-28F) |
| Vapor Density | 0.6 (lighter than air) |
| Water Reactivity | Highly soluble in water, forming caustic ammonium hydroxide solution. No violent reaction but generates heat. |
Fireground Response Guidance — UN 1005
Extinguishing Media
PPE Requirements
The minimum PPE level for responding to an ammonia spill or leak is Level B, with a positive pressure SCBA and chemical-resistant suit required due to the severe eye and respiratory hazard. Full face protection is also necessary, and gloves should be made of a material resistant to ammonia, such as butyl rubber or neoprene. The rationale for this PPE is to prevent skin contact and inhalation of the toxic and corrosive vapors.
Isolation & Evacuation
First Actions for a UN 1005 Incident
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area for at least 100 meters (330 feet) in all directions.
- For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.
- For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind
📋 Copy & Share Field Card
UN 1005 — Ammonia, anhydrousUse for: Quick radio or face-to-face size-up. Short, structured, field-ready.
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
Use for: Quick text to command or incoming units. Fits in a single SMS.