UN 2851 — Boron trifluoride, dihydrate
Placard: Corrosive. ERG Guide 157. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
Boron trifluoride, dihydrate is a corrosive, fuming boron fluoride hydrate. Response decisions should focus on acid gas control, moisture contact, and skin/eye protection.
Hazard overview: The material can release corrosive fluoride fumes in moist air or water contact. Direct water streams may increase fuming, splashing, and acidic runoff.
Response guidance: Isolate the area, monitor for acid gases, and keep unnecessary water away from the product. Use dry chemical, lime, soda ash, or compatible dry absorbent methods under hazmat supervision.
Firefighter training notes: Training should focus on moisture exclusion, dry extinguishing media, gas monitoring, and withdrawal distances for UN 2851.
Regulatory context: Verify the SDS, shipping papers, packaging condition, and ERG 157 before selecting water, neutralization, or cleanup tactics.
Storage & handling: Store dry and tightly closed, away from water, humidity, incompatible acids/bases, oxidizers, fuels, and ignition sources as specified by SDS.
UN 2851 Quick Details
Common Hazards of UN 2851
- Corrosive liquid or fuming material; contact can severely burn skin, eyes, and respiratory tissue.
- Moisture or water can generate heat and acidic fluoride-containing fumes.
- Vapors and mist may be heavier than air and collect in confined or low areas.
- Nonflammable itself, but fire exposure can produce toxic and corrosive decomposition gases.
- Runoff from water application can become acidic and toxic.
- Containers may fail when heated or contaminated.
- Hydrogen fluoride exposure risk requires careful PPE and decontamination planning.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid with a pungent, irritating odor. Fuming liquid that releases white vapors in moist air
| Also known as | Boron trifluoride hydrateBF3 dihydrateTrifluoroborane dihydrateBoron fluoride dihydrate |
| CAS Number | 13319-75-0 |
| Appearance | Colorless to pale yellow liquid with a pungent, irritating odor. Fuming liquid that releases white vapors in moist air. |
| Flash Point | Not applicable (non-flammable corrosive liquid) |
| Boiling Point | Approximately 106C (223F) with decomposition |
| Vapor Density | Greater than 1 (heavier than air) |
| Water Reactivity | Reacts with water releasing heat and corrosive/toxic hydrogen fluoride (HF) and boric acid; exothermic reaction increases vapor concentration |
Fireground Response Guidance — UN 2851
Extinguishing Media
PPE Requirements
SCBA and acid-resistant chemical protective clothing are required for release or fire conditions. Consider Level A where vapor concentration or splash risk is unknown.
Isolation & Evacuation
First Actions for a UN 2851 Incident
- Call 911 and the emergency response number shown on shipping papers or the SDS.
- Keep unauthorized personnel away and isolate the area from ignition and moisture sources.
- Stay upwind, uphill, and upstream; avoid low areas where corrosive fumes or hydrogen may collect.
- Avoid breathing fumes and prevent all skin and eye contact with material or runoff.
- Do not touch containers or residue without SCBA and chemical-resistant PPE.
- Do not apply water directly to the material unless specialist guidance confirms it is safe.
- Use ERG guidance, SDS, shipping papers, and monitoring for hydrogen, acid gases, and oxygen levels.
📋 Copy & Share Field Card
UN 2851 — Boron trifluoride, dihydrateUse 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.