☣️ UN 2561 • CLASS 3
UN 2561 — 3-Methyl-1-butene
Placard: Flammable. ERG Guide 128. 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 2561 Quick Details
UN 2561
Product name: 3-Methyl-1-butene
DOT Class: 3
Placard type: Flammable
ERG Guide: 128 (check current ERG)
Initial isolation: ERG 128: Initial isolation 100m all directions; protective action 800m downwind if large spill; consider ignition sources up to flash point area
Common Hazards of UN 2561
- 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 | Isopropylethylene3-Methylbutene-1IsoamyleneIsopentene |
| CAS Number | 563-45-1 |
| Appearance | Colorless liquid with a gasoline-like or hydrocarbon odor. Volatile organic compound at room temperature. |
| Flash Point | -54C (-65F) |
| Boiling Point | 20C (68F) |
| Vapor Density | 2.4 (heavier than air) |
| Water Reactivity | No significant reaction; insoluble in water, floats and forms flammable layer |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 2561
Extinguishing Media
AFFF, alcohol-resistant foam, dry chemical, CO2; water spray for cooling only
PPE Requirements
⚠️ Level B minimum with SCBA in vapor areas; butyl rubber or nitrile gloves; splash protection for liquid contact
Isolation & Evacuation
ERG 128: Initial isolation 100m all directions; protective action 800m downwind if large spill; consider ignition sources up to flash point area
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 128).
First Actions for a UN 2561 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 2561 — 3-Methyl-1-buteneHAZMAT RADIO NOTE — UN 2561
Product: 3-Methyl-1-butene
Class 3 / Flammable / ERG 128
PPE: Level B minimum with SCBA in vapor areas; butyl rubber or nitrile gloves; splash protection for liquid contact
ISOLATION: ERG 128: Initial isolation 100m all directions; protective action 800m downwind if large spill; consider ignition sources up to flash point area
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 2561 — 3-Methyl-1-butene
Class: 3 | Placard: Flammable | ERG Guide: 128
Appearance: Colorless liquid with a gasoline-like or hydrocarbon odor. Volatile organic compound at room temperature.
Water Reactivity: No significant reaction; insoluble in water, floats and forms flammable layer
Extinguishing: AFFF, alcohol-resistant foam, dry chemical, CO2; water spray for cooling only
PPE: Level B minimum with SCBA in vapor areas; butyl rubber or nitrile gloves; splash protection for liquid contact
Isolation: ERG 128: Initial isolation 100m all directions; protective action 800m downwind if large spill; consider ignition sources up to flash point area
— 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/2561 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2561 3-Methyl-1-butene Cls3 ERG128 | ERG 128: Initial isolation 100m all directions; protective action 800m downwind | allfirefighter.com/hazmat/un/2561SMS / 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/2561
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Frequently Asked Questions about UN 2561
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 with SCBA in vapor areas; butyl rubber or nitrile gloves; splash protection for liquid contact
Water reactivity: No significant reaction; insoluble in water, floats and forms flammable layer. Recommended extinguishing: AFFF, alcohol-resistant foam, dry chemical, CO2; water spray for cooling only.
ERG Guide 128 recommendation: ERG 128: Initial isolation 100m all directions; protective action 800m downwind if large spill; consider ignition sources up to flash point area
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 128 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.