UN 1811 — Potassium hydrogen difluoride, solid
Placard: Corrosive. ERG Guide 154. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1811 is Potassium hydrogen difluoride, solid, a toxic corrosive acid fluoride solid assigned to ERG Guide 154. Moisture can create acidic fluoride solution with hydrofluoric-acid-type exposure concerns.
Hazard overview: UN 1811 presents fluoride dust, corrosive contact, HF-type solution and contaminated-runoff hazards. Avoid dust and direct water contact unless incident command confirms a safe control method.
Response guidance: For a UN 1811 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 154. Establish incident command, isolate the area, stay upwind, prevent incompatible contact, control runoff and choose entry or fire-control actions based on monitoring, SDS and local SOP.
Firefighter training notes: Training for UN 1811 should emphasize corrosive exposure routes, water or oxidizer incompatibility where applicable, air monitoring, PPE selection, decontamination and runoff containment. Use ERG 154, SDS and local SOP.
Regulatory context: Potassium hydrogen difluoride, solid is regulated as a hazardous material for transportation and emergency response purposes. Transportation, workplace exposure, spill reporting, waste handling, storage and environmental requirements may vary by concentration, formulation, 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: Potassium hydrogen difluoride, solid should be stored in tightly closed compatible containers in a cool, dry, well-ventilated area away from water, moisture, bases, oxidizers/reducing agents where incompatible, heat and unauthorized access. Protect containers from corrosion, leakage and contamination.
UN 1811 Quick Details
Common Hazards of UN 1811
- TOXIC and CORROSIVE acid fluoride salt; inhalation, ingestion or skin contact may cause severe injury.
- Dissolves in water to form acidic fluoride solution and may generate hydrogen fluoride-type exposure hazards.
- Dust can seriously irritate or injure eyes, skin and respiratory tissue.
- Heating or fire may release corrosive/toxic fluoride gases.
- Runoff may carry toxic fluoride contamination.
- Containers may rupture or fail when heated.
- Avoid all skin contact and prevent dust from becoming airborne.
Chemical Identity & Physical Properties
White crystalline powder or solid with no distinctive odor. Hygroscopic and deliquescent, meaning it absorbs moisture from air.
| Also known as | Potassium bifluoridePotassium acid fluoridePotassium hydrogen fluorideKHF2 |
| CAS Number | 7789-29-9 |
| Appearance | White crystalline powder or solid with no distinctive odor. Hygroscopic and deliquescent, meaning it absorbs moisture from air. |
| Flash Point | Not applicable (inorganic salt) |
| Boiling Point | Not applicable (decomposes above 230C/446F) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Dissolves in water producing hydrofluoric acid solution - corrosive and toxic |
Fireground Response Guidance — UN 1811
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, fume, dust, fire or confined-space exposure. Chemical-resistant gloves, boots, eye/face protection and protective clothing should be selected from SDS; Level A may be needed for close entry or unknown concentrations.
Isolation & Evacuation
First Actions for a UN 1811 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, mist or spray and avoid skin or eye contact.
- Keep water and moisture away from released product unless incident command confirms a compatible cooling or control use.
- Do not touch or walk through 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 leak area and expand the perimeter if vapor, dust, fire involvement, water reaction or unknown concentration is present.
- Use ERG Guide 154, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1811 — Potassium hydrogen difluoride, solidUse 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.