☣️ UN 2742 • CLASS 6
Chloroformates, poisonous, corrosive, flammable, n.o.s.
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 2742
Class: 6
Placard type: Toxic
ERG: Guide 155 (check current ERG)
Isolation: ERG 155: Isolate spill 50m (150ft) all directions; evacuate immediate area; if tank/rail car involved in fire, isolate 800m (0.5 miles) in all directions
Chemical & Response Details
| Also known as | Chloroformate estersChlorocarbonic acid estersChloroformic acid estersCarbonic chloride derivatives |
| Appearance | Typically colorless to pale yellow liquids with pungent, irritating odors. Highly reactive organic compounds that are both corrosive and flammable at room temperature. |
| Flash Point | Varies by specific compound, typically below 23C (73F) - highly flammable |
| Boiling Point | Varies by specific chloroformate, typically 50-150C (122-302F) |
| Vapor Density | Heavier than air (typically 3-5 times air density) |
| Water Reactivity | Reacts violently with water producing HCl gas and CO2; highly exothermic reaction |
| Extinguishing | Dry chemical, CO2, or alcohol-resistant foam; water spray for cooling only from safe distance |
| PPE | ⚠️ Level A or B required; full-face SCBA mandatory; chemical-resistant suit; double gloves; extreme caution due to combined toxic, corrosive, and flammable hazards |
| Isolation | ERG 155: Isolate spill 50m (150ft) all directions; evacuate immediate area; if tank/rail car involved in fire, isolate 800m (0.5 miles) in all directions |
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 2742 — Chloroformates, poisonous, corrosive, fl HAZMAT RADIO NOTE — UN 2742
Product: Chloroformates, poisonous, corrosive, flammable, n.o.s.
Class 6 / Toxic / ERG 155
PPE: Level A or B required; full-face SCBA mandatory; chemical-resistant suit; double gloves; extreme caution due to combined toxic, corrosive, and flammable hazards
ISOLATION: ERG 155: Isolate spill 50m (150ft) all directions; evacuate immediate area; if tank/rail car involved in fire, isolate 800m (0.5 miles) in all directions
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 2742 — Chloroformates, poisonous, corrosive, flammable, n.o.s.
Class: 6 | Placard: Toxic | ERG Guide: 155
Appearance: Typically colorless to pale yellow liquids with pungent, irritating odors. Highly reactive organic compounds that are both corrosive and flammable at room temperature.
Water Reactivity: Reacts violently with water producing HCl gas and CO2; highly exothermic reaction
Extinguishing: Dry chemical, CO2, or alcohol-resistant foam; water spray for cooling only from safe distance
PPE: Level A or B required; full-face SCBA mandatory; chemical-resistant suit; double gloves; extreme caution due to combined toxic, corrosive, and flammable hazards
Isolation: ERG 155: Isolate spill 50m (150ft) all directions; evacuate immediate area; if tank/rail car involved in fire, isolate 800m (0.5 miles) in all directions
— 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/2742 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2742 Chloroformates, poisonous, corrosive, flammable, n.o.s. Cls6 ERG155 | allfirefighter.com/hazmat/un/2742SMS / 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/2742
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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 required; full-face SCBA mandatory; chemical-resistant suit; double gloves; extreme caution due to combined toxic, corrosive, and flammable hazards
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.