UN 2672 — Ammonium hydroxide, with more than 10% but not more than 35% ammonia
Placard: Corrosive. ERG Guide 154. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2672 is Ammonium hydroxide, with more than 10% but not more than 35% ammonia, a corrosive ammonia solution assigned to ERG Guide 154. Ammonia vapor, alkaline burns and concentration control are key concerns.
Hazard overview: CORROSIVE ammonia solution; vapor or mist can burn eyes, skin and respiratory tissue. Ammonia vapor can travel with wind and accumulate in poorly ventilated areas despite being lighter than air. Solution is not flammable, but released ammonia can form flammable mixtures at high concentrations.
Response guidance: For UN 2672, isolate the area, avoid mist or splash exposure and use SCBA where vapor/mist is present. Contain alkaline runoff, keep acids away and verify concentration controls with SDS and ERG 154.
Firefighter training notes: Training for UN 2672 should emphasize caustic burns, mist/vapor control, heat of dilution, acid incompatibility, decontamination and alkaline runoff containment. Use ERG 154, SDS and local SOP.
Regulatory context: Ammonium hydroxide, with more than 10% but not more than 35% ammonia is regulated as a hazardous material for transport and emergency response. Storage, exposure, spill reporting, waste and fire-code duties depend on quantity, concentration and jurisdiction; verify shipping papers, SDS and local authority requirements.
Storage & handling: Ammonium hydroxide, with more than 10% but not more than 35% ammonia should be stored in compatible corrosion-resistant containers with ventilation, secondary containment and segregation from acids, metals where incompatible and reactive materials.
UN 2672 Quick Details
Common Hazards of UN 2672
- CORROSIVE ammonia solution; vapor or mist can burn eyes, skin and respiratory tissue.
- Ammonia vapor can travel with wind and accumulate in poorly ventilated areas despite being lighter than air.
- Solution is not flammable, but released ammonia can form flammable mixtures at high concentrations.
- Mixing with acids releases heat and ammonia/chloramine-type hazards may occur with some incompatibles.
- Runoff may be alkaline, corrosive and harmful to waterways.
- Heating containers can increase pressure and ammonia vapor release.
- Exact concentration affects vapor pressure, corrosivity and response tactics.
Chemical Identity & Physical Properties
Clear to slightly yellow liquid with a pungent, suffocating odor of ammonia. Exists as aqueous solution at room temperature.
| Also known as | Aqueous ammoniaAmmonia solutionAmmonia waterHousehold ammoniaAmmonium hydroxide solution |
| CAS Number | 1336-21-6 |
| Appearance | Clear to slightly yellow liquid with a pungent, suffocating odor of ammonia. Exists as aqueous solution at room temperature. |
| Flash Point | Not applicable (non-flammable aqueous solution) |
| Boiling Point | Approximately 38C (100F) for 28% solution, varies with concentration |
| Vapor Density | 0.6 (lighter than air, ammonia vapor) |
| Water Reactivity | Miscible with water; dilution reduces hazard but generates heat |
Fireground Response Guidance — UN 2672
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, mist, dust, fire or confined-space exposure. Wear chemical-resistant gloves, boots, eye/face protection and protective clothing.
Isolation & Evacuation
First Actions for a UN 2672 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind, uphill and upstream.
- Avoid breathing vapor, dust, mist, smoke or fumes and avoid skin or eye contact.
- Do not touch damaged containers or spilled material without proper training and PPE.
- Prevent contaminated liquid, dust, runoff and decontamination waste from spreading.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 154, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2672 — Ammonium hydroxide, with more than 10% bUse 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.