☣️ UN 1777 • CLASS 8
UN 1777 — Fluorosulphonic acid
Placard: Corrosive. ERG Guide 137. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
🚒☣️
⚠️ 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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UN 1777 Quick Details
UN 1777
Product name: Fluorosulphonic acid
DOT Class: 8
Placard type: Corrosive
ERG Guide: 137 (check current ERG)
Initial isolation: ERG 137: Isolate spill 25-50m all directions. For large spill isolate 100m and evacuate downwind 300m. Contain runoff to prevent water contamination.
Common Hazards of UN 1777
- CORROSIVE and/or TOXIC; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance
- Fire will produce irritating, corrosive and/or toxic gases.
- Reaction with water may generate much heat that will increase the concentration of fumes in the air.
- Contact with molten substance may cause severe burns to skin and eyes.
- Runoff from fire control or dilution water may cause environmental contamination.
- EXCEPT FOR ACETIC ANHYDRIDE (UN1715), THAT IS FLAMMABLE, some of these materials may
- May ignite combustibles (wood, paper, oil, clothing, etc.).
- Substance will react with water (some violently), releasing corrosive and/or toxic gases and runoff.
Chemical Identity & Physical Properties
| Also known as | Fluorosulfuric acidFluorosulfonic acidFluosulfonic acidFSO3H |
| CAS Number | 7789-21-1 |
| Appearance | Colorless to straw-colored fuming liquid with a pungent, irritating odor. Fumes in moist air due to high reactivity with water vapor. |
| Flash Point | Not applicable (non-flammable corrosive liquid) |
| Boiling Point | 163°C (325°F) |
| Vapor Density | 3.5 (heavier than air) |
| Water Reactivity | Reacts violently with water generating heat and toxic/corrosive hydrogen fluoride and sulfuric acid fumes. Do not use water directly on material. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1777
Extinguishing Media
Do not use water or foam. Use dry chemical, soda ash, or lime to neutralize spills. CO2 for adjacent fires only.
PPE Requirements
⚠️ Level A required for significant releases. Full encapsulating suit with SCBA. Resistant materials: Teflon, Kel-F. Rubber and most metals corrode rapidly.
Isolation & Evacuation
ERG 137: Isolate spill 25-50m all directions. For large spill isolate 100m and evacuate downwind 300m. Contain runoff to prevent water contamination.
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 137).
First Actions for a UN 1777 Incident
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
- 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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📋 Copy & Share Field Card
UN 1777 — Fluorosulphonic acidHAZMAT RADIO NOTE — UN 1777
Product: Fluorosulphonic acid
Class 8 / Corrosive / ERG 137
PPE: Level A required for significant releases. Full encapsulating suit with SCBA. Resistant materials: Teflon, Kel-F. Rubber and most metals corrode rapidly.
ISOLATION: ERG 137: Isolate spill 25-50m all directions. For large spill isolate 100m and evacuate downwind 300m. Contain runoff to prevent water contamination.
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 1777 — Fluorosulphonic acid
Class: 8 | Placard: Corrosive | ERG Guide: 137
Appearance: Colorless to straw-colored fuming liquid with a pungent, irritating odor. Fumes in moist air due to high reactivity with water vapor.
Water Reactivity: Reacts violently with water generating heat and toxic/corrosive hydrogen fluoride and sulfuric acid fumes. Do not use water directly on material.
Extinguishing: Do not use water or foam. Use dry chemical, soda ash, or lime to neutralize spills. CO2 for adjacent fires only.
PPE: Level A required for significant releases. Full encapsulating suit with SCBA. Resistant materials: Teflon, Kel-F. Rubber and most metals corrode rapidly.
Isolation: ERG 137: Isolate spill 25-50m all directions. For large spill isolate 100m and evacuate downwind 300m. Contain runoff to prevent water contamination.
— Key Hazards —
• CORROSIVE and/or TOXIC; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance
• Fire will produce irritating, corrosive and/or toxic gases.
• Reaction with water may generate much heat that will increase the concentration of fumes in the air.
— 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.
• Ventilate closed spaces before entering, but only if properly trained and equipped.
SOURCE: allfirefighter.com/hazmat/un/1777 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1777 Fluorosulphonic acid Cls8 ERG137 | ERG 137: Isolate spill 25-50m all directions. For large spill isolate 100m and e | allfirefighter.com/hazmat/un/1777SMS / 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/1777
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Frequently Asked Questions about UN 1777
CORROSIVE and/or TOXIC; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance Fire will produce irritating, corrosive and/or toxic gases. Reaction with water may generate much heat that will increase the concentration of fumes in the air. Contact with molten substance may cause severe burns to skin and eyes. Runoff from fire control or dilution water may cause environmental contamination. EXCEPT FOR ACETIC ANHYDRIDE (UN1715), THAT IS FLAMMABLE, some of these materials may May ignite combustibles (wood, paper, oil, clothing, etc.). Substance will react with water (some violently), releasing corrosive and/or toxic gases and runoff.
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 required for significant releases. Full encapsulating suit with SCBA. Resistant materials: Teflon, Kel-F. Rubber and most metals corrode rapidly.
Water reactivity: Reacts violently with water generating heat and toxic/corrosive hydrogen fluoride and sulfuric acid fumes. Do not use water directly on material.. Recommended extinguishing: Do not use water or foam. Use dry chemical, soda ash, or lime to neutralize spills. CO2 for adjacent fires only..
ERG Guide 137 recommendation: ERG 137: Isolate spill 25-50m all directions. For large spill isolate 100m and evacuate downwind 300m. Contain runoff to prevent water contamination.
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 137 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.