☣️ UN 2459 • CLASS 3
2-Methyl-1-butene
Placard: Flammable. 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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Quick details
UN 2459
Class: 3
Placard type: Flammable
ERG: Guide 128 (check current ERG)
Isolation: ERG 128: isolate 100m all directions; evacuate 800m downwind if tank/rail car involved in fire
Chemical & Response Details
| Also known as | 2-Methylbutene-12-Methylbut-1-eneα-IsoamyleneIsopentene |
| CAS Number | 563-46-2 |
| Appearance | Colorless liquid with a characteristic hydrocarbon odor. Highly volatile at room temperature. |
| Flash Point | -20C (-4F) |
| Boiling Point | 31C (88F) |
| Vapor Density | 2.4 (heavier than air) |
| Water Reactivity | No significant reaction; immiscible and floats on water |
| Extinguishing | AFFF foam, alcohol-resistant foam, CO2, dry chemical; water fog for cooling only |
| PPE | ⚠️ Level B minimum; SCBA required in vapor areas; fire proximity suits for fire situations |
| Isolation | ERG 128: isolate 100m all directions; evacuate 800m downwind if tank/rail car involved in fire |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- 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.
First actions (field-minded)
- 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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UN 2459 — 2-Methyl-1-butene HAZMAT RADIO NOTE — UN 2459
Product: 2-Methyl-1-butene
Class 3 / Flammable / ERG 128
PPE: Level B minimum; SCBA required in vapor areas; fire proximity suits for fire situations
ISOLATION: ERG 128: isolate 100m all directions; 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 2459 — 2-Methyl-1-butene
Class: 3 | Placard: Flammable | ERG Guide: 128
Appearance: Colorless liquid with a characteristic hydrocarbon odor. Highly volatile at room temperature.
Water Reactivity: No significant reaction; immiscible and floats on water
Extinguishing: AFFF foam, alcohol-resistant foam, CO2, dry chemical; water fog for cooling only
PPE: Level B minimum; SCBA required in vapor areas; fire proximity suits for fire situations
Isolation: ERG 128: isolate 100m all directions; 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/2459 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2459 2-Methyl-1-butene Cls3 ERG128 | ERG 128: isolate 100m all directions; evacuate 800m downwind if tank/rail car in | allfirefighter.com/hazmat/un/2459SMS / 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/2459
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FAQ
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; SCBA required in vapor areas; fire proximity suits for fire situations
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.