UN 1786 — Hydrofluoric acid and sulphuric acid mixture
Placard: Corrosive. ERG Guide 157. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1786 is Hydrofluoric acid and sulphuric acid mixture, a Class 8 toxic corrosive acid mixture assigned to ERG Guide 157. It combines hydrofluoric acid systemic toxicity with sulphuric acid heat and fuming hazards.
Hazard overview: UN 1786 presents HF skin penetration, severe acid burns, toxic/corrosive vapor and contaminated-runoff hazards. Dilution may generate heat and increase fuming, while contact with metals may release hydrogen gas.
Response guidance: For a UN 1786 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 157. 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 1786 should emphasize HF systemic toxicity, sulphuric acid heat generation, fume control, runoff containment, PPE compatibility, decontamination and medical coordination. Use ERG 157, SDS and local SOP.
Regulatory context: Hydrofluoric acid and sulphuric acid mixture 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: Hydrofluoric acid and sulphuric acid mixture 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 1786 Quick Details
Common Hazards of UN 1786
- TOXIC and CORROSIVE acid mixture; inhalation, ingestion or skin/eye contact may cause severe injury or death.
- Contains hydrofluoric acid, which can penetrate skin and cause deep tissue injury that may be delayed and life-threatening.
- Sulphuric acid component can generate intense heat during dilution and worsen burns or fuming.
- Vapors or mist are highly irritating and corrosive to eyes, skin and respiratory tissue.
- Contact with metals may generate flammable hydrogen gas.
- Fire may produce irritating, corrosive and/or toxic gases.
- Runoff may be strongly acidic, fluoride-contaminated and environmentally hazardous.
Chemical Identity & Physical Properties
Clear to slightly colored fuming liquid mixture with a sharp, pungent, irritating odor. Highly corrosive and generates toxic vapors.
| Also known as | HF-H2SO4 mixturehydrofluoric-sulfuric acid mixturefluorosulfuric acid mixtureHF/sulfuric acid blend |
| Appearance | Clear to slightly colored fuming liquid mixture with a sharp, pungent, irritating odor. Highly corrosive and generates toxic vapors. |
| Flash Point | Not applicable (non-flammable corrosive liquid) |
| Boiling Point | Variable depending on mixture ratio, typically 100-160C (212-320F) |
| Vapor Density | Heavier than air (vapors sink and concentrate in low areas) |
| Water Reactivity | Reacts with water generating heat and increasing toxic vapor concentration; violent spattering may occur |
Fireground Response Guidance — UN 1786
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and acid-resistant chemical protective clothing for any vapor, mist or liquid exposure. Level A may be needed for close entry; PPE and medical planning should account for hydrofluoric acid exposure and follow SDS, monitoring and local hazmat SOP.
Isolation & Evacuation
First Actions for a UN 1786 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 157, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1786 — Hydrofluoric acid and sulphuric acid mixUse 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.