UN 2682 — Caesium hydroxide
Placard: Corrosive. ERG Guide 157. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2682 At a Glance
UN 2682 (Caesium hydroxide) is listed as DOT Class 8 Corrosive and is assigned to ERG Guide 157. Use this page to review placard data, common hazards, PPE notes, isolation context, first actions, and related UN numbers.
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.