UN 2682 — Caesium hydroxide
Placard: Corrosive. ERG Guide 157. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2682 is Caesium hydroxide, a strongly corrosive alkali hydroxide solid assigned to ERG Guide 157. Moisture creates caustic heat and runoff hazards.
Hazard overview: STRONGLY CORROSIVE alkali hydroxide solid; dust or solution can cause severe burns. Hygroscopic solid absorbs moisture and forms strongly alkaline corrosive solution. Dissolves in water with heat release; splattering or steam generation may occur.
Response guidance: For UN 2682, 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 157.
Firefighter training notes: Training for UN 2682 should emphasize caustic burns, mist/vapor control, heat of dilution, acid incompatibility, decontamination and alkaline runoff containment. Use ERG 157, SDS and local SOP.
Regulatory context: Caesium hydroxide 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: Caesium hydroxide should be stored in compatible corrosion-resistant containers with ventilation, secondary containment and segregation from acids, metals where incompatible and reactive materials.
UN 2682 Quick Details
Common Hazards of UN 2682
- STRONGLY CORROSIVE alkali hydroxide solid; dust or solution can cause severe burns.
- Hygroscopic solid absorbs moisture and forms strongly alkaline corrosive solution.
- Dissolves in water with heat release; splattering or steam generation may occur.
- Non-combustible, but contact with some metals may generate flammable hydrogen gas.
- Runoff may be strongly alkaline and harmful to waterways.
- Containers may fail when heated or exposed to moisture.
- Avoid dust generation and direct unprotected contact.
Chemical Identity & Physical Properties
White to yellowish deliquescent crystalline solid or pellets. Highly hygroscopic, absorbs moisture from air. Odorless.
| Also known as | Cesium hydroxideCaesium hydrateCesium hydrateCsOH |
| CAS Number | 21351-79-1 |
| Appearance | White to yellowish deliquescent crystalline solid or pellets. Highly hygroscopic, absorbs moisture from air. Odorless. |
| Flash Point | Not applicable (inorganic solid) |
| Boiling Point | Not applicable (decomposes) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Reacts vigorously with water generating heat and forming highly caustic solution; may generate flammable hydrogen gas |
Fireground Response Guidance — UN 2682
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 2682 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 157, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2682 — Caesium hydroxideUse 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.