UN 2331 — Zinc chloride, anhydrous
Placard: Corrosive. ERG Guide 154. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2331 is Zinc chloride, anhydrous, a corrosive anhydrous zinc chloride solid assigned to ERG Guide 154. Moisture can form acidic/corrosive solution and heat.
Hazard overview: CORROSIVE anhydrous zinc chloride; dust, mist or solution can burn eyes, skin and respiratory tissue. Reacts with water or moisture to release heat and form strongly acidic/corrosive solution. Fumes or smoke from heated material can cause severe respiratory irritation.
Response guidance: For a UN 2331 incident, verify the product with shipping papers, container markings, SDS and ERG Guide 154. Establish incident command, isolate the area, stay upwind, control ignition or incompatibility hazards, prevent runoff, dust or vapor spread and base entry/fire-control actions on monitoring and local SOP.
Firefighter training notes: Training for UN 2331 should emphasize toxic/corrosive exposure routes, contaminated clothing, toxic fire products, decontamination waste and runoff containment. Use ERG 154, SDS and local SOP.
Regulatory context: Zinc chloride, anhydrous 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: Zinc chloride, anhydrous should be stored dry in tightly closed compatible containers away from water/moisture, bases, metals where incompatible and unauthorized access. Protect packaging from humidity and provide acidic runoff containment.
UN 2331 Quick Details
Common Hazards of UN 2331
- CORROSIVE anhydrous zinc chloride; dust, mist or solution can burn eyes, skin and respiratory tissue.
- Reacts with water or moisture to release heat and form strongly acidic/corrosive solution.
- Fumes or smoke from heated material can cause severe respiratory irritation.
- Non-combustible, but fire may produce irritating/corrosive metal chloride fumes.
- Runoff may be acidic, corrosive and harmful to waterways.
- Containers may rupture or fail when heated or contaminated with water.
- Avoid dust generation and moisture contact during spill handling.
Chemical Identity & Physical Properties
White to grayish-white crystalline solid or granular powder. Odorless to slight odor. Highly hygroscopic, absorbs moisture from air.
| Also known as | Butter of zincZinc dichlorideZinc(II) chlorideZnCl2 |
| CAS Number | 7646-85-7 |
| Appearance | White to grayish-white crystalline solid or granular powder. Odorless to slight odor. Highly hygroscopic, absorbs moisture from air. |
| Flash Point | Not applicable (non-flammable solid) |
| Boiling Point | 732C (1350F) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Dissolves in water with heat generation; highly exothermic reaction, may cause solution to boil |
Fireground Response Guidance — UN 2331
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for dust, mist, vapor, fire or confined-space exposure. Wear chemical-resistant gloves, boots, eye/face protection and protective clothing selected from SDS; Level A may be needed for unknown concentrations.
Isolation & Evacuation
First Actions for a UN 2331 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.
- Avoid breathing vapors, dust, mist, smoke or fumes and avoid skin or eye contact.
- Avoid unnecessary water contact with released product unless incident command confirms a compatible control use.
- Do not touch damaged containers or spilled 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, dust generation, water reaction or unknown product identity.
- Use ERG Guide 154, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 2331 — Zinc chloride, 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.