☣️ UN 1234 • CLASS 3
UN 1234 — Methylal
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 1234 Quick Details
UN 1234
Product name: Methylal
DOT Class: 3
Placard type: Flammable
ERG Guide: 127 (check current ERG)
Initial isolation: ERG 127: Initial isolation 50m all directions; protective action distance 0.3km for large spill; eliminate ignition sources
Common Hazards of UN 1234
- 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 | DimethoxymethaneFormalMethylene dimethyl etherDimethyl formal |
| CAS Number | 109-87-5 |
| Appearance | Colorless, volatile liquid with a chloroform-like or ethereal odor. Highly mobile and evaporates readily at room temperature. |
| Flash Point | -32°C (-26°F) |
| Boiling Point | 42°C (108°F) |
| Vapor Density | 2.6 (heavier than air) |
| Water Reactivity | Slightly soluble in water; no significant reaction |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1234
Extinguishing Media
Alcohol-resistant foam, CO2, dry chemical, water spray for cooling
PPE Requirements
⚠️ Level B minimum with SCBA; avoid all ignition sources; butyl rubber gloves recommended
Isolation & Evacuation
ERG 127: Initial isolation 50m all directions; protective action distance 0.3km for large spill; eliminate ignition sources
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 127).
First Actions for a UN 1234 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 1234 — MethylalHAZMAT RADIO NOTE — UN 1234
Product: Methylal
Class 3 / Flammable / ERG 127
PPE: Level B minimum with SCBA; avoid all ignition sources; butyl rubber gloves recommended
ISOLATION: ERG 127: Initial isolation 50m all directions; protective action distance 0.3km for large spill; eliminate ignition sources
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 1234 — Methylal
Class: 3 | Placard: Flammable | ERG Guide: 127
Appearance: Colorless, volatile liquid with a chloroform-like or ethereal odor. Highly mobile and evaporates readily at room temperature.
Water Reactivity: Slightly soluble in water; no significant reaction
Extinguishing: Alcohol-resistant foam, CO2, dry chemical, water spray for cooling
PPE: Level B minimum with SCBA; avoid all ignition sources; butyl rubber gloves recommended
Isolation: ERG 127: Initial isolation 50m all directions; protective action distance 0.3km for large spill; eliminate ignition sources
— 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/1234 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1234 Methylal Cls3 ERG127 | ERG 127: Initial isolation 50m all directions; protective action distance 0.3km | allfirefighter.com/hazmat/un/1234SMS / 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/1234
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Frequently Asked Questions about UN 1234
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; avoid all ignition sources; butyl rubber gloves recommended
Water reactivity: Slightly soluble in water; no significant reaction. Recommended extinguishing: Alcohol-resistant foam, CO2, dry chemical, water spray for cooling.
ERG Guide 127 recommendation: ERG 127: Initial isolation 50m all directions; protective action distance 0.3km for large spill; eliminate ignition sources
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.