☣️ UN 2398 • CLASS 3
UN 2398 — Methyl tert-butyl ether
Placard: Flammable. ERG Guide 127. 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 2398 Quick Details
UN 2398
Product name: Methyl tert-butyl ether
DOT Class: 3
Placard type: Flammable
ERG Guide: 127 (check current ERG)
Initial isolation: ERG 127: Small spill isolate 50m all directions; large spill isolate 150m all directions, evacuate 800m downwind if tank/rail car involved in fire
Common Hazards of UN 2398
- 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 | MTBEtert-Butyl methyl ether2-Methoxy-2-methylpropaneMethyl t-butyl etherDriveron |
| CAS Number | 1634-04-4 |
| Appearance | Colorless liquid with a distinctive ether-like or terpene-like odor. Volatile and highly flammable at ambient temperatures. |
| Flash Point | -28°C (-18°F) |
| Boiling Point | 55°C (131°F) |
| Vapor Density | 3.1 (heavier than air) |
| Water Reactivity | No significant reaction; slightly soluble in water (approximately 4-5% by weight) |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 2398
Extinguishing Media
Alcohol-resistant foam (AR-AFFF), CO2, dry chemical; regular AFFF may be ineffective
PPE Requirements
⚠️ Level B minimum for spill response; SCBA required in confined spaces or high vapor concentrations; splash-resistant chemical protective clothing
Isolation & Evacuation
ERG 127: Small spill isolate 50m all directions; large spill isolate 150m all directions, 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 2398 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 2398 — Methyl tert-butyl etherHAZMAT RADIO NOTE — UN 2398
Product: Methyl tert-butyl ether
Class 3 / Flammable / ERG 127
PPE: Level B minimum for spill response; SCBA required in confined spaces or high vapor concentrations; splash-resistant chemical protective clothing
ISOLATION: ERG 127: Small spill isolate 50m all directions; large spill isolate 150m 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 2398 — Methyl tert-butyl ether
Class: 3 | Placard: Flammable | ERG Guide: 127
Appearance: Colorless liquid with a distinctive ether-like or terpene-like odor. Volatile and highly flammable at ambient temperatures.
Water Reactivity: No significant reaction; slightly soluble in water (approximately 4-5% by weight)
Extinguishing: Alcohol-resistant foam (AR-AFFF), CO2, dry chemical; regular AFFF may be ineffective
PPE: Level B minimum for spill response; SCBA required in confined spaces or high vapor concentrations; splash-resistant chemical protective clothing
Isolation: ERG 127: Small spill isolate 50m all directions; large spill isolate 150m 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/2398 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2398 Methyl tert-butyl ether Cls3 ERG127 | allfirefighter.com/hazmat/un/2398SMS / 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/2398
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Frequently Asked Questions about UN 2398
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 for spill response; SCBA required in confined spaces or high vapor concentrations; splash-resistant chemical protective clothing
Water reactivity: No significant reaction; slightly soluble in water (approximately 4-5% by weight). Recommended extinguishing: Alcohol-resistant foam (AR-AFFF), CO2, dry chemical; regular AFFF may be ineffective.
ERG Guide 127 recommendation: ERG 127: Small spill isolate 50m all directions; large spill isolate 150m all directions, 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.