UN 1831 — Sulphuric acid, fuming
Placard: Corrosive. ERG Guide 137. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1831 is Sulphuric acid, fuming, also known as oleum, a fuming Class 8 corrosive acid assigned to ERG Guide 137. It contains dissolved sulfur trioxide and can release dense corrosive acid mist.
Hazard overview: UN 1831 presents severe acid burns, heat-on-dilution, corrosive mist and acidic-runoff hazards. Contact with some metals may release flammable hydrogen gas.
Response guidance: For a UN 1831 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 137. 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 1831 should emphasize strong acid burns, heat from dilution, fume control, incompatibility with organics/metals where relevant, runoff containment and decontamination. Use ERG 137, SDS and local SOP.
Regulatory context: Sulphuric acid, fuming 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: Sulphuric acid, fuming should be stored in compatible acid-resistant containers with secondary containment, away from water, bases, organics, combustibles, reducing agents where incompatible, reactive metals and unauthorized access. Keep containers closed and protected from heat and contamination.
UN 1831 Quick Details
Common Hazards of UN 1831
- EXTREMELY CORROSIVE fuming sulfuric acid/oleum; vapor, mist or liquid contact may cause severe injury.
- Contains dissolved sulfur trioxide and can fume heavily in moist air.
- Dilution with water can generate intense heat, boiling and spattering.
- Contact with some metals may release flammable hydrogen gas.
- Fire or heating may produce sulfur oxides and irritating/corrosive mist.
- Runoff may be strongly acidic, corrosive and environmentally harmful.
- Containers may rupture or fail when heated.
- Keep incompatible organics, bases and reactive metals away.
Chemical Identity & Physical Properties
Dense, colorless to dark brown oily liquid that fumes heavily in moist air, producing thick white vapors with a pungent, choking odor. Contains dissolved sulfur trioxide (SO3) in concentrated sulfuric acid.
| Also known as | OleumFuming sulfuric acidDisulfuric acidPyrosulfuric acidNordhauser acid |
| CAS Number | 8014-95-7 |
| Appearance | Dense, colorless to dark brown oily liquid that fumes heavily in moist air, producing thick white vapors with a pungent, choking odor. Contains dissolved sulfur trioxide (SO3) in concentrated sulfuric acid. |
| Flash Point | Not applicable (non-flammable) |
| Boiling Point | Approximately 338C (640F), varies with SO3 concentration |
| Vapor Density | 3.4 (heavier than air) |
| Water Reactivity | Reacts violently with water, generating extreme heat and spattering. Never add water to acid. May boil and release dense toxic SO3 fumes. |
Fireground Response Guidance — UN 1831
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for dust, vapor, mist, fire or confined-space exposure. Wear chemical-resistant gloves, boots, eye/face protection and protective clothing selected from SDS for corrosive contact.
Isolation & Evacuation
First Actions for a UN 1831 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.
- 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 137, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1831 — Sulphuric acid, fumingUse 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.