☣️ UN 1238 • CLASS 6
Methyl chloroformate
Placard: Toxic. 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 1238
Class: 6
Placard type: Toxic
ERG: Guide 155 (check current ERG)
Isolation: ERG 155: isolate spill 50m all directions; evacuate 300m downwind if large spill; 800m if tank/rail car involved in fire
Chemical & Response Details
| Also known as | Chloromethyl formateFormic acid chloromethyl esterMethyl chlorocarbonateMethylchloroformateMCF |
| CAS Number | 79-22-1 |
| Appearance | Colorless liquid with a pungent, irritating odor. Denser than water and volatile at room temperature. |
| Flash Point | 12°C (54°F) |
| Boiling Point | 71°C (160°F) |
| Vapor Density | 3.3 (heavier than air) |
| Water Reactivity | Reacts slowly with water, releasing HCl and CO2; avoid direct water contact, use water spray carefully |
| Extinguishing | Alcohol-resistant foam, CO2, dry chemical; water may be ineffective |
| PPE | ⚠️ Level A or B minimum; full-face SCBA required; chemical-resistant suit; avoid all skin/eye contact |
| Isolation | ERG 155: isolate spill 50m all directions; evacuate 300m downwind if large spill; 800m 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 form explosive mixtures with air: indoors, outdoors and sewers explosion hazards.
- Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas
- Vapors may travel to source of ignition and flash back.
- Those substances designated with a (P) may polymerize explosively when heated or involved in a fire.
- Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff.
- Corrosives in contact with metals may evolve flammable hydrogen gas.
- Containers may explode when heated or if contaminated with water.
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 in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
- For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.
- For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind
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UN 1238 — Methyl chloroformate HAZMAT RADIO NOTE — UN 1238
Product: Methyl chloroformate
Class 6 / Toxic / ERG 155
PPE: Level A or B minimum; full-face SCBA required; chemical-resistant suit; avoid all skin/eye contact
ISOLATION: ERG 155: isolate spill 50m all directions; evacuate 300m downwind if large spill; 800m 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 1238 — Methyl chloroformate
Class: 6 | Placard: Toxic | ERG Guide: 155
Appearance: Colorless liquid with a pungent, irritating odor. Denser than water and volatile at room temperature.
Water Reactivity: Reacts slowly with water, releasing HCl and CO2; avoid direct water contact, use water spray carefully
Extinguishing: Alcohol-resistant foam, CO2, dry chemical; water may be ineffective
PPE: Level A or B minimum; full-face SCBA required; chemical-resistant suit; avoid all skin/eye contact
Isolation: ERG 155: isolate spill 50m all directions; evacuate 300m downwind if large spill; 800m if tank/rail car involved in fire
— Key Hazards —
• HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames.
• Vapors form explosive mixtures with air: indoors, outdoors and sewers explosion hazards.
• Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas
— 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/1238 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1238 Methyl chloroformate Cls6 ERG155 | ERG 155: isolate spill 50m all directions; evacuate 300m downwind if large spill | allfirefighter.com/hazmat/un/1238SMS / 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/1238
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FAQ
HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors form explosive mixtures with air: indoors, outdoors and sewers explosion hazards. Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas Vapors may travel to source of ignition and flash back. Those substances designated with a (P) may polymerize explosively when heated or involved in a fire. Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff. Corrosives in contact with metals may evolve flammable hydrogen gas. Containers may explode when heated or if contaminated with water.
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 A or B minimum; full-face SCBA required; chemical-resistant suit; avoid all skin/eye contact
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 155 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.