UN 1829 — Sulphur trioxide, stabilized
Placard: Corrosive. ERG Guide 137. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1829 is Sulphur trioxide, stabilized, a stabilized fuming corrosive material assigned to ERG Guide 137. Moisture can generate dense sulfuric acid mist and intense heat.
Hazard overview: UN 1829 presents violent water reaction, sulfuric acid mist, corrosive vapor and acidic-runoff hazards. Avoid direct water contact and use specialist hazmat control.
Response guidance: For a UN 1829 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 1829 should emphasize water-reactive fuming liquid behavior, dense acid vapor clouds, dry-agent selection, downwind control, PPE selection and decontamination. Use ERG 137, SDS and local hazmat SOP.
Regulatory context: Sulphur trioxide, stabilized 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: Sulphur trioxide, stabilized 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 1829 Quick Details
Common Hazards of UN 1829
- EXTREMELY CORROSIVE fuming material; inhalation or contact can cause severe injury.
- Reacts violently with water or moist air, generating intense heat and dense sulfuric acid mist.
- Vapors and acid mist are heavier than air and may collect in low or poorly ventilated areas.
- Non-flammable, but reaction heat and corrosive mist can intensify incident hazards.
- Runoff may become strongly acidic and corrosive.
- Containers may rupture or fail when heated or contaminated with water.
- Avoid all water contact with the product unless specialist guidance directs otherwise.
Chemical Identity & Physical Properties
Colorless to white crystalline solid or fuming liquid (depending on form and temperature). Pungent, choking odor. Reacts violently with moisture in air to form dense white fumes of sulfuric acid.
| Also known as | Sulfur trioxideSulphuric anhydrideSO3Sulfuric oxide |
| CAS Number | 7446-11-9 |
| Appearance | Colorless to white crystalline solid or fuming liquid (depending on form and temperature). Pungent, choking odor. Reacts violently with moisture in air to form dense white fumes of sulfuric acid. |
| Flash Point | Not applicable (non-flammable) |
| Boiling Point | 45C (113F) |
| Vapor Density | 2.8 (heavier than air) |
| Water Reactivity | Reacts violently with water, generating intense heat and forming sulfuric acid mist. NEVER use water directly on material. |
Fireground Response Guidance — UN 1829
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, fume, fire or confined-space exposure. Chemical-resistant gloves, boots, eye/face protection and protective clothing should be selected from SDS; Level A may be needed for close entry or unknown concentrations.
Isolation & Evacuation
First Actions for a UN 1829 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 137, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1829 — Sulphur trioxide, stabilizedUse 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.