☣️ UN 1754 • CLASS 8
UN 1754 — Chlorosulphonic acid (with or without sulphur trioxide)
Placard: Corrosive. ERG Guide 137. 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.
Chlorosulphonic acid is a highly corrosive and toxic substance that can cause severe burns and eye damage. It is essential to handle this substance with extreme caution and follow proper safety protocols.
Hazard overview: Chlorosulphonic acid is a corrosive and toxic substance that can cause severe burns and eye damage. It reacts violently with moisture in air, producing dense white fumes of hydrochloric acid and sulfuric acid mist.
Response guidance: In case of an emergency, evacuate the area immediately and stay upwind. Use dry chemical, soda ash, or lime to extinguish the fire, but avoid using water, foam, or CO2.
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UN 1754 Quick Details
UN 1754
Product name: Chlorosulphonic acid (with or without sulphur trioxide)
DOT Class: 8
Placard type: Corrosive
ERG Guide: 137 (check current ERG)
Initial isolation: ERG 137: Isolate spill area 50m in all directions. For large spill, isolate 800m downwind. Evacuate immediate area and stay upwind.
Common Hazards of UN 1754
- 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
Chlorosulphonic acid is a colorless to pale yellow fuming liquid with a pungent, acrid odor and extremely corrosive.
| Also known as | chlorosulfuric acidsulfuric chlorohydrinmonochlorosulfuric acidsulfurochloridic acid |
| CAS Number | 7790-94-5 |
| Appearance | Colorless to pale yellow fuming liquid with a pungent, acrid odor. Extremely corrosive and reacts violently with moisture in air, producing dense white fumes of hydrochloric acid and sulfuric acid mist. |
| Flash Point | Not applicable (non-flammable liquid) |
| Boiling Point | 151-152C (304-306F) |
| Vapor Density | 4.0 (heavier than air) |
| Water Reactivity | Reacts violently with water, generating intense heat and toxic/corrosive fumes (HCl, SO2, H2SO4). Never apply water directly. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1754
Extinguishing Media
Dry chemical, soda ash, lime. Do NOT use water, foam, or CO2.
PPE Requirements
⚠️ Level A required for spill response. Full encapsulating chemical protective suit, SCBA, butyl rubber or Viton gloves. Acid-resistant boots.
Wear Level A required PPE with full encapsulating chemical protective suit, SCBA, butyl rubber or Viton gloves, and acid-resistant boots.
Isolation & Evacuation
ERG 137: Isolate spill area 50m in all directions. For large spill, isolate 800m downwind. Evacuate immediate area and stay upwind.
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 137).
First Actions for a UN 1754 Incident
- 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 1754 — Chlorosulphonic acid (with or without suHAZMAT RADIO NOTE — UN 1754
Product: Chlorosulphonic acid (with or without sulphur trioxide)
Class 8 / Corrosive / ERG 137
PPE: Level A required for spill response. Full encapsulating chemical protective suit, SCBA, butyl rubber or Viton gloves. Acid-resistant boots.
ISOLATION: ERG 137: Isolate spill area 50m in all directions. For large spill, isolate 800m downwind. Evacuate immediate area and stay upwind.
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 1754 — Chlorosulphonic acid (with or without sulphur trioxide)
Class: 8 | Placard: Corrosive | ERG Guide: 137
Appearance: Colorless to pale yellow fuming liquid with a pungent, acrid odor. Extremely corrosive and reacts violently with moisture in air, producing dense white fumes of hydrochloric acid and sulfuric acid mist.
Water Reactivity: Reacts violently with water, generating intense heat and toxic/corrosive fumes (HCl, SO2, H2SO4). Never apply water directly.
Extinguishing: Dry chemical, soda ash, lime. Do NOT use water, foam, or CO2.
PPE: Level A required for spill response. Full encapsulating chemical protective suit, SCBA, butyl rubber or Viton gloves. Acid-resistant boots.
Isolation: ERG 137: Isolate spill area 50m in all directions. For large spill, isolate 800m downwind. Evacuate immediate area and stay upwind.
— 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 —
• 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
SOURCE: allfirefighter.com/hazmat/un/chlorosulphonic-acid-un-1754 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN1754 Chlorosulphonic acid (with or without sulphur trioxide) Cls8 ERG137 | allfirefighter.com/hazmat/un/chlorosulphonic-acid-un-1754SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/chlorosulphonic-acid-un-1754
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Frequently Asked Questions about UN 1754
Yes, and it can cause severe burns and eye damage.
No, due to violent reaction.
Level A required with full encapsulating chemical protective suit, SCBA, butyl rubber or Viton gloves, and acid-resistant boots.
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.