UN 1645 — Mercury sulphate
Placard: Toxic. ERG Guide 151. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1645 is Mercury sulphate, a toxic mercury compound assigned to ERG Guide 151. It may form corrosive or toxic solutions, and fire can produce persistent mercury contamination.
Hazard overview: UN 1645 presents toxic mercury exposure, dust/solution contact and contaminated-runoff hazards. Some salts are corrosive in solution, and heating may produce toxic mercury or halogen/sulfur-containing fumes.
Response guidance: For a UN 1645 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 151. Establish incident command, isolate the area, stay upwind, prevent dust or vapor exposure, control runoff and choose entry or cleanup actions based on monitoring, SDS and local SOP.
Firefighter training notes: Training for UN 1645 should emphasize mercury salt toxicity, dust or solution contamination, SCBA use, runoff containment, decontamination and waste-control coordination. Use ERG 151, SDS and local SOP.
Regulatory context: Mercury sulphate is regulated as a toxic mercury hazardous material. Transportation, occupational exposure, spill reporting, waste handling, storage and environmental controls may vary by compound, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Mercury sulphate should be stored in tightly closed compatible containers in a secure, cool, dry, well-ventilated toxic-material area away from food, incompatible chemicals, heat and unauthorized access. Prevent dust release, solution leaks and mercury-contaminated runoff.
UN 1645 Quick Details
Common Hazards of UN 1645
- TOXIC and potentially corrosive mercury compound; inhalation, ingestion or skin contact may cause severe injury.
- Dust, solution or contaminated residue can be hazardous by skin contact, ingestion or inhalation.
- Some mercury salts form corrosive or acidic solutions in water.
- Fire or heating may produce toxic mercury fumes and corrosive halogen, sulfur or organic decomposition products.
- Runoff may spread persistent toxic mercury contamination.
- Containers may rupture or fail when heated.
- Avoid all unnecessary contact with solid, solution, dust and contaminated equipment.
Chemical Identity & Physical Properties
White crystalline solid or powder. Odorless. Dense heavy metal salt that is stable under normal conditions.
| Also known as | Mercuric sulphateMercury(II) sulfateMercuric sulfateSulfuric acid mercury(2+) salt |
| CAS Number | 7783-35-9 |
| Appearance | White crystalline solid or powder. Odorless. Dense heavy metal salt that is stable under normal conditions. |
| Flash Point | Not applicable (non-flammable solid) |
| Boiling Point | Decomposes before boiling |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Soluble in water forming acidic solution; no violent reaction but releases toxic mercury compounds |
Fireground Response Guidance — UN 1645
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for dust, vapor, fire or confined-space exposure. Chemical-resistant gloves, eye/face protection and protective clothing should be selected from SDS; prevent skin contact and mercury-contaminated dust or runoff spread.
Isolation & Evacuation
First Actions for a UN 1645 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, fumes, dust or mist and avoid all skin or eye contact.
- Do not touch or walk through spilled material unless properly trained and wearing appropriate protective equipment.
- Avoid creating dust clouds or spreading contaminated liquid, powder, solution, runoff or debris.
- Ventilate closed spaces before entering, but only if properly trained, equipped, monitored and authorized by incident command.
- Isolate the spill or leak area and expand the perimeter if dust, vapor, fire involvement or unknown concentration is present.
- Use ERG Guide 151, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1645 — Mercury sulphateUse 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.