UN 2439 — Sodium hydrogendifluoride
Placard: Corrosive. ERG Guide 154. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2439 is Sodium hydrogendifluoride, a toxic corrosive fluoride salt assigned to ERG Guide 154. Water can form hydrogen-fluoride-containing corrosive solution.
Hazard overview: TOXIC and CORROSIVE fluoride salt; inhalation, ingestion or skin contact may cause severe injury. Dissolves in water to form corrosive and toxic hydrogen fluoride-containing solution. Dust or solution can burn eyes, skin and respiratory tissue.
Response guidance: For UN 2439, isolate the area, avoid skin contact and use SCBA where dust, vapor, mist or fire is present. Contain toxic/corrosive runoff and verify exact product controls with SDS and ERG 154.
Firefighter training notes: Training for UN 2439 should emphasize toxic/corrosive exposure routes, skin absorption, SCBA use, decontamination, runoff containment and SDS verification. Use ERG 154, SDS and local SOP.
Regulatory context: Sodium hydrogendifluoride 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: Sodium hydrogendifluoride should be stored dry in tightly closed compatible containers away from moisture, bases, metals where incompatible and unauthorized access. Provide containment for acidic/corrosive runoff.
UN 2439 Quick Details
Common Hazards of UN 2439
- TOXIC and CORROSIVE fluoride salt; inhalation, ingestion or skin contact may cause severe injury.
- Dissolves in water to form corrosive and toxic hydrogen fluoride-containing solution.
- Dust or solution can burn eyes, skin and respiratory tissue.
- Non-combustible, but heating can release corrosive fluoride fumes.
- Contact with metals may generate flammable hydrogen gas under some conditions.
- Runoff may be acidic/fluoride-contaminated and harmful to waterways.
- Avoid dust generation and all skin/eye contact.
Chemical Identity & Physical Properties
White crystalline solid or powder. Odorless or slight acidic odor. Stable at room temperature.
| Also known as | Sodium bifluorideSodium hydrogen fluorideSodium acid fluorideNaHF2 |
| CAS Number | 1333-83-1 |
| Appearance | White crystalline solid or powder. Odorless or slight acidic odor. Stable at room temperature. |
| Flash Point | Not applicable (non-combustible solid) |
| Boiling Point | Not applicable (decomposes before boiling) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Dissolves in water producing corrosive and toxic hydrogen fluoride solution |
Fireground Response Guidance — UN 2439
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and chemical-resistant protective clothing. Level A may be needed for heavy vapor, fuming, splash risk or unknown concentrations.
Isolation & Evacuation
First Actions for a UN 2439 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 dust, liquid, 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 2439 — Sodium hydrogendifluorideUse 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.