UN 2191 — Sulphuryl fluoride
Placard: Toxic Gas. ERG Guide 123. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2191 is Sulphuryl fluoride, a toxic fumigant gas assigned to ERG Guide 123. It may be odorless and requires strict exclusion, monitoring and ventilation.
Hazard overview: TOXIC compressed fumigant gas; inhalation may be fatal. Non-flammable, but fire may produce toxic/corrosive fluoride and sulfur oxide gases. Gas is heavier than air and may collect in low or confined areas.
Response guidance: For a UN 2191 incident, verify the product with shipping papers, container markings, SDS and ERG Guide 123. Establish incident command, isolate the area, stay upwind, control ignition or incompatibility hazards, prevent runoff or vapor spread and base entry/fire-control actions on monitoring and local SOP.
Firefighter training notes: Training for UN 2191 should emphasize toxic gas isolation, air monitoring, downwind protection, Level A entry decisions, cylinder control, decontamination and medical coordination. Use ERG 123, SDS and local SOP.
Regulatory context: Sulphuryl fluoride is regulated as a hazardous material for transportation and emergency response purposes. Storage, workplace exposure, emergency planning, spill reporting, waste handling and environmental requirements vary by exact product, concentration, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, container markings and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Sulphuryl fluoride containers should be secured in a cool, ventilated gas storage area away from heat, physical damage and incompatible materials. Toxic, corrosive, oxidizing or refrigerated gases require leak detection/ventilation and emergency planning as specified by SDS and local code.
UN 2191 Quick Details
Common Hazards of UN 2191
- TOXIC compressed fumigant gas; inhalation may be fatal.
- Non-flammable, but fire may produce toxic/corrosive fluoride and sulfur oxide gases.
- Gas is heavier than air and may collect in low or confined areas.
- Odor is not a reliable warning; product may be odorless or warning agent may not be present.
- Containers may rupture or rocket when heated.
- Exposure may cause delayed neurological or respiratory effects.
- Ventilation, monitoring and strict exclusion zones are critical.
Chemical Identity & Physical Properties
Colorless, odorless compressed gas at room temperature. Has a slight sulfur dioxide-like odor only at very high concentrations.
| Also known as | Sulfuryl fluorideVikaneSO2F2Sulfonyl fluorideSulfur dioxide difluoride |
| CAS Number | 2699-79-8 |
| Appearance | Colorless, odorless compressed gas at room temperature. Has a slight sulfur dioxide-like odor only at very high concentrations. |
| Flash Point | Not applicable (non-flammable gas) |
| Boiling Point | -55C (-67F) |
| Vapor Density | 3.5 (heavier than air) |
| Water Reactivity | Hydrolyzes slowly in water to form hydrogen fluoride and sulfuric acid; reaction is slow at ambient conditions |
Fireground Response Guidance — UN 2191
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and fully encapsulating chemical protective clothing for close entry or unknown concentrations. Level A may be needed; protect against frostbite where liquefied or refrigerated gas contact is possible.
Isolation & Evacuation
First Actions for a UN 2191 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.
- Treat the release as a serious inhalation hazard and consider downwind protective actions using ERG and incident command.
- Avoid breathing vapors, gas, dust, mist, smoke or fumes and avoid skin or eye contact.
- Do not touch damaged containers or spilled/released 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 release area and expand the perimeter for fire involvement, vapor spread, gas accumulation, cylinder heating or unknown product identity.
- Use ERG Guide 123, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 2191 — Sulphuryl fluorideUse 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.