UN 2073 — Ammonia solution, with more than 35% but not more than 50% ammonia
Placard: Non-Flammable Gas. ERG Guide 125. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2073 is Ammonia solution, with more than 35% but not more than 50% ammonia, a concentrated ammonia solution assigned to ERG Guide 125. It produces toxic/corrosive ammonia vapor and can cause severe respiratory or chemical burn injury.
Hazard overview: TOXIC and CORROSIVE concentrated ammonia solution; vapor inhalation can cause severe respiratory injury. Vapors are strongly irritating and corrosive to eyes, skin and mucous membranes. Ammonia vapor is lighter than air but can travel with cold mist or in poorly ventilated areas.
Response guidance: For a UN 2073 incident, verify the product with shipping papers, container markings, SDS and ERG Guide 125. Establish incident command, isolate the area, stay upwind, control ignition or incompatibility hazards, prevent runoff or vapor spread and base entry/fire-control actions on monitoring and local SOP.
Firefighter training notes: Training for UN 2073 should emphasize exposure routes, air monitoring, PPE selection, fire behavior, decontamination, runoff containment and ERG/SDS verification. Use ERG 125, SDS and local SOP.
Regulatory context: Ammonia solution, with more than 35% but not more than 50% ammonia is regulated as a hazardous material for transportation and emergency response purposes. Storage, workplace exposure, emergency planning, spill reporting, waste handling and environmental requirements vary by exact product, concentration, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, container markings and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Ammonia solution, with more than 35% but not more than 50% ammonia should be stored in tightly closed compatible containers in a secure, ventilated toxic/corrosive area with secondary containment, restricted access and segregation from incompatible chemicals according to SDS.
UN 2073 Quick Details
Common Hazards of UN 2073
- TOXIC and CORROSIVE concentrated ammonia solution; vapor inhalation can cause severe respiratory injury.
- Vapors are strongly irritating and corrosive to eyes, skin and mucous membranes.
- Ammonia vapor is lighter than air but can travel with cold mist or in poorly ventilated areas.
- Mixing with acids, chlorine, hypochlorites or other cleaners can release toxic gases or heat.
- Contact with liquid can cause chemical burns; concentrated vapor may be fatal.
- Runoff may be alkaline, toxic to aquatic life and environmentally harmful.
- Containers may rupture or fail when heated.
Chemical Identity & Physical Properties
Clear to slightly yellow liquid with a pungent, suffocating odor. Strong irritating ammonia smell detectable at very low concentrations.
| Also known as | Aqua ammoniaAmmonium hydroxide solutionAmmonia waterHousehold ammonia (concentrated)Aqueous ammonia |
| CAS Number | 1336-21-6 |
| Appearance | Clear to slightly yellow liquid with a pungent, suffocating odor. Strong irritating ammonia smell detectable at very low concentrations. |
| Flash Point | Not applicable (non-flammable solution) |
| Boiling Point | Approximately 24-38C (75-100F) depending on concentration |
| Vapor Density | 0.6 (lighter than air, ammonia vapor rises) |
| Water Reactivity | Miscible with water; dilution generates heat but no violent reaction |
Fireground Response Guidance — UN 2073
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, mist, fire or confined-space exposure. Wear chemical-resistant gloves, boots, eye/face protection and protective clothing selected for concentrated ammonia.
Isolation & Evacuation
First Actions for a UN 2073 Incident
- CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Treat the release as a serious inhalation hazard and consider downwind protective actions using ERG and incident command.
- Avoid breathing vapors, gas, dust, mist, smoke or fumes and avoid skin or eye contact.
- Do not touch damaged containers or spilled/released material unless properly trained and wearing appropriate protective equipment.
- Ventilate closed spaces before entering, but only if properly trained, equipped, monitored and authorized by incident command.
- Isolate the spill or release area and expand the perimeter for fire involvement, vapor spread, gas accumulation, cylinder heating or unknown product identity.
- Use ERG Guide 125, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 2073 — Ammonia solution, with more than 35% butUse 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.