☣️ UN 2789 • CLASS 8
UN 2789 — Acetic acid, solution, more than 80% acid
Placard: Corrosive. ERG Guide 132. 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 2789 Quick Details
UN 2789
Product name: Acetic acid, solution, more than 80% acid
DOT Class: 8
Placard type: Corrosive
ERG Guide: 132 (check current ERG)
Initial isolation: ERG 132: isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m all directions
Common Hazards of UN 2789
- Flammable/combustible material.
- May be ignited by heat, sparks or flames.
- Vapors may form explosive mixtures with air.
- Vapors may travel to source of ignition and flash back.
- Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas
- Vapor explosion hazard indoors, outdoors or in sewers.
- Those substances designated with a (P) may polymerize explosively when heated or involved in a fire.
- Runoff to sewer may create fire or explosion hazard.
Chemical Identity & Physical Properties
| Also known as | Glacial acetic acidEthanoic acidVinegar acidMethanecarboxylic acid |
| CAS Number | 64-19-7 |
| Appearance | Clear, colorless liquid with a pungent, vinegar-like odor. Corrosive and miscible with water. |
| Flash Point | 39°C (103°F) |
| Boiling Point | 118°C (244°F) |
| Vapor Density | 2.1 (heavier than air) |
| Water Reactivity | Miscible with water; exothermic dilution generates heat but no violent reaction |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 2789
Extinguishing Media
Alcohol-resistant foam, CO2, dry chemical; water spray for cooling only
PPE Requirements
⚠️ Level B minimum; SCBA and chemical-resistant suit required due to corrosive vapors
Isolation & Evacuation
ERG 132: isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m all directions
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 132).
First Actions for a UN 2789 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 for at least 50 meters (150 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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📋 Copy & Share Field Card
UN 2789 — Acetic acid, solution, more than 80% aciHAZMAT RADIO NOTE — UN 2789
Product: Acetic acid, solution, more than 80% acid
Class 8 / Corrosive / ERG 132
PPE: Level B minimum; SCBA and chemical-resistant suit required due to corrosive vapors
ISOLATION: ERG 132: isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m all directions
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 2789 — Acetic acid, solution, more than 80% acid
Class: 8 | Placard: Corrosive | ERG Guide: 132
Appearance: Clear, colorless liquid with a pungent, vinegar-like odor. Corrosive and miscible with water.
Water Reactivity: Miscible with water; exothermic dilution generates heat but no violent reaction
Extinguishing: Alcohol-resistant foam, CO2, dry chemical; water spray for cooling only
PPE: Level B minimum; SCBA and chemical-resistant suit required due to corrosive vapors
Isolation: ERG 132: isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m all directions
— Key Hazards —
• Flammable/combustible material.
• May be ignited by heat, sparks or flames.
• Vapors may form explosive mixtures with 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/2789 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2789 Acetic acid, solution, more than 80% acid Cls8 ERG132 | allfirefighter.com/hazmat/un/2789SMS / 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/2789
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Frequently Asked Questions about UN 2789
Flammable/combustible material. May be ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas Vapor explosion hazard indoors, outdoors or in sewers. Those substances designated with a (P) may polymerize explosively when heated or involved in a fire. Runoff to sewer may create fire or explosion hazard.
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 B minimum; SCBA and chemical-resistant suit required due to corrosive vapors
Water reactivity: Miscible with water; exothermic dilution generates heat but no violent reaction. Recommended extinguishing: Alcohol-resistant foam, CO2, dry chemical; water spray for cooling only.
ERG Guide 132 recommendation: ERG 132: isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m all directions
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 132 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.