☣️ UN 1811 • CLASS 8
UN 1811 — Potassium hydrogen difluoride, solid
Placard: Corrosive. ERG Guide 154. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
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⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
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UN 1811 Quick Details
UN 1811
Product name: Potassium hydrogen difluoride, solid
DOT Class: 8
Placard type: Corrosive
ERG Guide: 154 (check current ERG)
Initial isolation: ERG 154: Initial isolation 50m all directions; protective action distance 0.2km daytime, 0.4km nighttime for small spills
Common Hazards of UN 1811
- TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury
- Contact with molten substance may cause severe burns to skin and eyes.
- Avoid any skin contact.
- Fire may produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or dilution water may be corrosive and/or toxic and cause environmental
- Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive
- Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.).
- Corrosives in contact with metals may evolve flammable hydrogen gas.
Chemical Identity & Physical Properties
| 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 |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1811
Extinguishing Media
Dry chemical, soda ash, lime; avoid water spray directly on material
PPE Requirements
⚠️ Level B minimum; full face respirator with acid gas cartridge, acid-resistant gloves, boots, and suit; SCBA for fire or high concentrations
Isolation & Evacuation
ERG 154: Initial isolation 50m all directions; protective action distance 0.2km daytime, 0.4km nighttime for small spills
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 154).
First Actions for a UN 1811 Incident
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
- For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.
- For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind
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📋 Copy & Share Field Card
UN 1811 — Potassium hydrogen difluoride, solidHAZMAT RADIO NOTE — UN 1811
Product: Potassium hydrogen difluoride, solid
Class 8 / Corrosive / ERG 154
PPE: Level B minimum; full face respirator with acid gas cartridge, acid-resistant gloves, boots, and suit; SCBA for fire or high concentrations
ISOLATION: ERG 154: Initial isolation 50m all directions; protective action distance 0.2km daytime, 0.4km nighttime for small spills
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 1811 — Potassium hydrogen difluoride, solid
Class: 8 | Placard: Corrosive | ERG Guide: 154
Appearance: White crystalline powder or solid with no distinctive odor. Hygroscopic and deliquescent, meaning it absorbs moisture from air.
Water Reactivity: Dissolves in water producing hydrofluoric acid solution - corrosive and toxic
Extinguishing: Dry chemical, soda ash, lime; avoid water spray directly on material
PPE: Level B minimum; full face respirator with acid gas cartridge, acid-resistant gloves, boots, and suit; SCBA for fire or high concentrations
Isolation: ERG 154: Initial isolation 50m all directions; protective action distance 0.2km daytime, 0.4km nighttime for small spills
— Key Hazards —
• TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury
• Contact with molten substance may cause severe burns to skin and eyes.
• Avoid any skin contact.
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Ventilate closed spaces before entering, but only if properly trained and equipped.
SOURCE: allfirefighter.com/hazmat/un/1811 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1811 Potassium hydrogen difluoride, solid Cls8 ERG154 | allfirefighter.com/hazmat/un/1811SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS. Includes link to full page.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/1811
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Frequently Asked Questions about UN 1811
TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause environmental Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Corrosives in contact with metals may evolve flammable hydrogen gas.
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper Keep unauthorized personnel away. Stay upwind, uphill and/or upstream.
Level B minimum; full face respirator with acid gas cartridge, acid-resistant gloves, boots, and suit; SCBA for fire or high concentrations
Water reactivity: Dissolves in water producing hydrofluoric acid solution - corrosive and toxic. Recommended extinguishing: Dry chemical, soda ash, lime; avoid water spray directly on material.
ERG Guide 154 recommendation: ERG 154: Initial isolation 50m all directions; protective action distance 0.2km daytime, 0.4km nighttime for small spills
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 154 and your department SOP/SOG for incident-specific protective actions.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles.
This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.