☣️ UN 2346 • CLASS 3
UN 2346 — Butanedione
Placard: Flammable. ERG Guide 127. 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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UN 2346 Quick Details
UN 2346
Product name: Butanedione
DOT Class: 3
Placard type: Flammable
ERG Guide: 127 (check current ERG)
Initial isolation: ERG 127: Small spill isolate 30m, large spill 100m; evacuate 800m downwind if tank/rail car involved in fire
Common Hazards of UN 2346
- HIGHLY FLAMMABLE: Will be easily 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.
- Containers may explode when heated.
Chemical Identity & Physical Properties
| Also known as | Diacetyl2,3-ButanedioneBiacetylDimethyl diketoneDimethylglyoxal |
| CAS Number | 431-03-8 |
| Appearance | Yellow to green liquid with a strong, pungent buttery odor. Exists as a liquid at room temperature. |
| Flash Point | -2°C (28°F) |
| Boiling Point | 88°C (190°F) |
| Vapor Density | 3.0 (heavier than air) |
| Water Reactivity | Soluble in water; no violent reaction expected |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 2346
Extinguishing Media
Alcohol-resistant foam, dry chemical, CO2, water spray
PPE Requirements
⚠️ Level B minimum in vapor areas; SCBA and chemical-resistant suit for spill response
Isolation & Evacuation
ERG 127: Small spill isolate 30m, large spill 100m; evacuate 800m downwind if tank/rail car involved in fire
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 127).
First Actions for a UN 2346 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.
- Consider initial downwind evacuation for at least 300 meters (1000 feet).
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📋 Copy & Share Field Card
UN 2346 — ButanedioneHAZMAT RADIO NOTE — UN 2346
Product: Butanedione
Class 3 / Flammable / ERG 127
PPE: Level B minimum in vapor areas; SCBA and chemical-resistant suit for spill response
ISOLATION: ERG 127: Small spill isolate 30m, large spill 100m; evacuate 800m downwind if tank/rail car involved in fire
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 2346 — Butanedione
Class: 3 | Placard: Flammable | ERG Guide: 127
Appearance: Yellow to green liquid with a strong, pungent buttery odor. Exists as a liquid at room temperature.
Water Reactivity: Soluble in water; no violent reaction expected
Extinguishing: Alcohol-resistant foam, dry chemical, CO2, water spray
PPE: Level B minimum in vapor areas; SCBA and chemical-resistant suit for spill response
Isolation: ERG 127: Small spill isolate 30m, large spill 100m; evacuate 800m downwind if tank/rail car involved in fire
— Key Hazards —
• HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames.
• Vapors may form explosive mixtures with air.
• Vapors may travel to source of ignition and flash back.
— 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/2346 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2346 Butanedione Cls3 ERG127 | ERG 127: Small spill isolate 30m, large spill 100m; evacuate 800m downwind if ta | allfirefighter.com/hazmat/un/2346SMS / 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/2346
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Frequently Asked Questions about UN 2346
HIGHLY FLAMMABLE: Will be easily 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. Containers may explode when heated.
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 in vapor areas; SCBA and chemical-resistant suit for spill response
Water reactivity: Soluble in water; no violent reaction expected. Recommended extinguishing: Alcohol-resistant foam, dry chemical, CO2, water spray.
ERG Guide 127 recommendation: ERG 127: Small spill isolate 30m, large spill 100m; evacuate 800m downwind if tank/rail car involved in fire
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 127 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.