☣️ UN 1727 • CLASS 8
UN 1727 — Ammonium hydrogendifluoride, 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.
Ammonium hydrogendifluoride is a highly toxic and corrosive substance that requires special handling and safety precautions. It is a white crystalline solid or powder with a sharp, pungent odor.
Hazard overview: Inhalation, ingestion, or skin contact with ammonium hydrogendifluoride may cause severe injury. Contact with molten substance may cause severe burns to skin and eyes.
Response guidance: In case of emergency, evacuate the area immediately and call the fire department. Use dry chemical, CO2, or dry sand to extinguish fires, and avoid direct contact with the material.
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UN 1727 Quick Details
UN 1727
Product name: Ammonium hydrogendifluoride, solid
DOT Class: 8
Placard type: Corrosive
ERG Guide: 154 (check current ERG)
Initial isolation: ERG 154: Initial isolation 50m in all directions. Spill: daytime 100m, nighttime 200m downwind. Fire: evacuate 800m radius if tank/railcar involved.
Common Hazards of UN 1727
- 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
Ammonium hydrogendifluoride is a white crystalline solid or powder that deliquescent (absorbs moisture from air).
| Also known as | Ammonium bifluorideAmmonium hydrogen fluorideAmmonium acid fluorideABF |
| CAS Number | 1341-49-7 |
| Appearance | White crystalline solid or powder with a sharp, pungent odor. Deliquescent (absorbs moisture from air). |
| Flash Point | Not applicable (non-flammable solid) |
| Boiling Point | Decomposes at 240C (464F) releasing hydrogen fluoride gas |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Soluble in water, forming acidic and corrosive solution. Hydrolyzes to release hydrogen fluoride in moist conditions. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1727
Extinguishing Media
Dry chemical, CO2, or dry sand. Water spray may be used to cool containers but avoid direct contact with material.
PPE Requirements
⚠️ Level B minimum required. Full face SCBA, acid-resistant suit, neoprene or butyl rubber gloves. Avoid all skin and eye contact due to severe burn hazard from fluoride.
Level B minimum personal protective equipment (PPE) is required, including full face SCBA, acid-resistant suit, and neoprene or butyl rubber gloves.
Isolation & Evacuation
ERG 154: Initial isolation 50m in all directions. Spill: daytime 100m, nighttime 200m downwind. Fire: evacuate 800m radius if tank/railcar involved.
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 154).
First Actions for a UN 1727 Incident
- 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 1727 — Ammonium hydrogendifluoride, solidHAZMAT RADIO NOTE — UN 1727
Product: Ammonium hydrogendifluoride, solid
Class 8 / Corrosive / ERG 154
PPE: Level B minimum required. Full face SCBA, acid-resistant suit, neoprene or butyl rubber gloves. Avoid all skin and eye contact due to severe burn hazard from fluoride.
ISOLATION: ERG 154: Initial isolation 50m in all directions. Spill: daytime 100m, nighttime 200m downwind. Fire: evacuate 800m radius if tank/railcar involved.
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 1727 — Ammonium hydrogendifluoride, solid
Class: 8 | Placard: Corrosive | ERG Guide: 154
Appearance: White crystalline solid or powder with a sharp, pungent odor. Deliquescent (absorbs moisture from air).
Water Reactivity: Soluble in water, forming acidic and corrosive solution. Hydrolyzes to release hydrogen fluoride in moist conditions.
Extinguishing: Dry chemical, CO2, or dry sand. Water spray may be used to cool containers but avoid direct contact with material.
PPE: Level B minimum required. Full face SCBA, acid-resistant suit, neoprene or butyl rubber gloves. Avoid all skin and eye contact due to severe burn hazard from fluoride.
Isolation: ERG 154: Initial isolation 50m in all directions. Spill: daytime 100m, nighttime 200m downwind. Fire: evacuate 800m radius if tank/railcar involved.
— 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 —
• 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
SOURCE: allfirefighter.com/hazmat/un/1727 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN1727 Ammonium hydrogendifluoride, solid Cls8 ERG154 | allfirefighter.com/hazmat/un/1727SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/ammonium-hydrogendifluoride-solid-un-1727
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Frequently Asked Questions about UN 1727
No, UN 1727 is not flammable.
Yes, UN 1727 reacts with water to form an acidic and corrosive solution.
UN 1727 is a toxic and corrosive substance that can cause severe injury through inhalation, ingestion, or skin contact.
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.