UN 1775 — Fluoroboric acid
Placard: Corrosive. ERG Guide 154. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
Fluoroboric acid is a colorless to slightly yellow liquid with a pungent, acrid odor, used as a corrosive aqueous solution, typically at a 48-50% concentration in water. It poses significant health and environmental risks due to its toxic and corrosive properties.
Hazard overview: Inhalation, ingestion, or skin contact with fluoroboric acid may cause severe injury, and contact with the molten substance can cause severe burns to skin and eyes. These risks require careful handling and emergency response to mitigate accidents.
Response guidance: In the event of an emergency, responders should isolate the spill area and consider initial isolation of 800m all directions if a tank or rail car is involved. They should use soda ash or lime for neutralization, as foam is not needed, and wear full protective gear including SCBA and acid-resistant suits.
UN 1775 Quick Details
Common Hazards of UN 1775
- 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
Fluoroboric acid is a colorless to slightly yellow liquid with a pungent, acrid odor, which is soluble in water and releases heat when diluted.
| Also known as | Tetrafluoroboric acidBorofluoric acidHydrogen tetrafluoroborateFluoroborate |
| CAS Number | 16872-11-0 |
| Appearance | Colorless to slightly yellow liquid with a pungent, acrid odor. Corrosive aqueous solution, typically 48-50% concentration in water. |
| Flash Point | Not applicable (non-flammable aqueous solution) |
| Boiling Point | 130C (266F) for 48% solution; decomposes at higher temperatures |
| Vapor Density | Not applicable (aqueous solution, heavier than air vapors) |
| Water Reactivity | Soluble in water, releases heat when diluted; already an aqueous solution |
Fireground Response Guidance — UN 1775
Extinguishing Media
PPE Requirements
Responders must wear Level B minimum protective gear, including full-face SCBA, acid-resistant suits, and butyl or neoprene gloves, to prevent injury from fluoroboric acid exposure.
Isolation & Evacuation
First Actions for a UN 1775 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
📋 Copy & Share Field Card
UN 1775 — Fluoroboric acidUse 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.