☣️ UN 2191 • CLASS 2
Sulphuryl fluoride
Placard: Toxic Gas. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
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⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
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Quick details
UN 2191
Class: 2
Placard type: Toxic Gas
ERG: Guide 123 (check current ERG)
Isolation: ERG 123: Initial isolation 100m in all directions; protective action distance 300m downwind (day), 600m downwind (night) for small spills
Chemical & Response Details
| 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 |
| Extinguishing | Not applicable (non-flammable); ventilate area, no extinguishing agents needed |
| PPE | ⚠️ Level A or B required; SCBA mandatory; gas is highly toxic and odorless at dangerous concentrations; chemical-resistant suit for liquid contact (frostbite hazard) |
| Isolation | ERG 123: Initial isolation 100m in all directions; protective action distance 300m downwind (day), 600m downwind (night) for small spills |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- TOXIC; may be fatal if inhaled or absorbed through skin.
- Vapors may be irritating and/or corrosive.
- Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
- Fire will produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or dilution water may cause environmental contamination.
- Some may burn but none ignite readily.
- Vapors from liquefied gas are initially heavier than air and spread along ground.
- Cylinders exposed to fire may vent and release toxic and/or corrosive gas through pressure relief
First actions (field-minded)
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Many gases are heavier than air and will spread along the ground and collect in low or confined areas
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area for at least 100 meters (330 feet) in all directions.
- 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
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UN 2191 — Sulphuryl fluoride HAZMAT RADIO NOTE — UN 2191
Product: Sulphuryl fluoride
Class 2 / Toxic Gas / ERG 123
PPE: Level A or B required; SCBA mandatory; gas is highly toxic and odorless at dangerous concentrations; chemical-resistant suit for liquid contact (frostbite hazard)
ISOLATION: ERG 123: Initial isolation 100m in all directions; protective action distance 300m downwind (day), 600m downwind (night) for small spills
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 2191 — Sulphuryl fluoride
Class: 2 | Placard: Toxic Gas | ERG Guide: 123
Appearance: Colorless, odorless compressed gas at room temperature. Has a slight sulfur dioxide-like odor only at very high concentrations.
Water Reactivity: Hydrolyzes slowly in water to form hydrogen fluoride and sulfuric acid; reaction is slow at ambient conditions
Extinguishing: Not applicable (non-flammable); ventilate area, no extinguishing agents needed
PPE: Level A or B required; SCBA mandatory; gas is highly toxic and odorless at dangerous concentrations; chemical-resistant suit for liquid contact (frostbite hazard)
Isolation: ERG 123: Initial isolation 100m in all directions; protective action distance 300m downwind (day), 600m downwind (night) for small spills
— Key Hazards —
• TOXIC; may be fatal if inhaled or absorbed through skin.
• Vapors may be irritating and/or corrosive.
• Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Many gases are heavier than air and will spread along the ground and collect in low or confined areas
SOURCE: allfirefighter.com/hazmat/un/2191 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2191 Sulphuryl fluoride Cls2 ERG123 | ERG 123: Initial isolation 100m in all directions; protective action distance 30 | allfirefighter.com/hazmat/un/2191SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS. Includes link to full page.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions. Page: https://allfirefighter.com/hazmat/un/2191
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FAQ
TOXIC; may be fatal if inhaled or absorbed through skin. Vapors may be irritating and/or corrosive. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may cause environmental contamination. Some may burn but none ignite readily. Vapors from liquefied gas are initially heavier than air and spread along ground. Cylinders exposed to fire may vent and release toxic and/or corrosive gas through pressure relief
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper Keep unauthorized personnel away. Stay upwind, uphill and/or upstream.
Level A or B required; SCBA mandatory; gas is highly toxic and odorless at dangerous concentrations; chemical-resistant suit for liquid contact (frostbite hazard)
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 123 and your department SOP/SOG for incident-specific protective actions.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles. This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.