☣️ UN 2742 • CLASS 6
UN 2742 — Chloroformates, poisonous, corrosive, flammable, n.o.s.
Placard: Toxic. ERG Guide 155. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
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⚠️ Verification required:
Broad or variable material category; verify exact product, SDS and shipping papers.
⚠️ 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.
Chloroformates, poisonous, corrosive, flammable, n.o.s. is a variable class entry. Treat it as flammable, toxic, corrosive and moisture-reactive until the exact SDS is confirmed.
Hazard overview: The hazards include flammable vapor travel, corrosive liquid contact and moisture decomposition that can release HCl and pressure. Exact behavior depends on the chloroformate.
Response guidance: Isolate the area, remove ignition sources and prevent water from contacting the liquid. Use dry chemical, CO2 or alcohol-resistant foam; cool intact containers from a protected distance.
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UN 2742 Quick Details
UN 2742
Product name: Chloroformates, poisonous, corrosive, flammable, n.o.s.
DOT Class: 6
Placard type: Toxic
ERG Guide: 155 (check current ERG)
Initial 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
Common Hazards of UN 2742
- Broad n.o.s. chloroformate entry; exact product identity controls flash point and toxicity.
- Flammable vapors may form explosive mixtures and flash back.
- Liquid and vapor are toxic and corrosive to eyes, skin and respiratory tissue.
- Water or moisture can decompose many chloroformates, releasing hydrogen chloride, carbon dioxide and heat.
- Closed contaminated containers may pressurize and rupture.
- Fire can produce highly toxic acid gases and carbonyl chloride-type decomposition products.
- Runoff may be acidic, toxic and flammable.
Chemical Identity & Physical Properties
Typically colorless to pale yellow liquids with pungent, irritating odors. Highly reactive organic compounds that are both corrosive and flammable at room temperature
| 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 |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 2742
Extinguishing Media
Dry chemical, CO2, or alcohol-resistant foam; water spray for cooling only from safe distance
PPE Requirements
⚠️ Level A or B required; full-face SCBA mandatory; chemical-resistant suit; double gloves; extreme caution due to combined toxic, corrosive, and flammable hazards
Use SCBA and chemical-protective clothing; Level A is appropriate where vapor concentration, product identity or splash risk is unknown.
Isolation & Evacuation
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
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 155).
First Actions for a UN 2742 Incident
- Call 911 and the emergency response number shown on the shipping papers.
- Keep unauthorized personnel away and deny entry to the spill or fire area.
- Stay upwind, uphill and upstream; avoid low areas where vapors or runoff may collect.
- Avoid breathing dust, vapor, mist or smoke; prevent skin and eye contact.
- Do not touch damaged containers or spilled material without appropriate PPE.
- Ventilate confined spaces only if personnel are trained, equipped and monitored.
- Use the ERG, SDS, shipping papers and air monitoring to set isolation, PPE and tactical decisions.
- Keep product-specific SDS and shipping papers with command because tactical limits vary by formulation.
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📋 Copy & Share Field Card
UN 2742 — Chloroformates, poisonous, corrosive, flHAZMAT 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 —
• Broad n.o.s. chloroformate entry; exact product identity controls flash point and toxicity.
• Flammable vapors may form explosive mixtures and flash back.
• Liquid and vapor are toxic and corrosive to eyes, skin and respiratory tissue.
— First Actions —
• Call 911 and the emergency response number shown on the shipping papers.
• Keep unauthorized personnel away and deny entry to the spill or fire area.
• Stay upwind, uphill and upstream; avoid low areas where vapors or runoff may collect.
• Avoid breathing dust, vapor, mist or smoke; prevent skin and eye contact.
SOURCE: allfirefighter.com/hazmat/un/chloroformates-poisonous-corrosive-flammable-un-2742 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN2742 Chloroformates, poisonous, corrosive, flammable, n.o.s. Cls6 ERG155 | allfirefighter.com/hazmat/un/chloroformates-poisonous-corrosive-flammable-un-2742SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/chloroformates-poisonous-corrosive-flammable-un-2742
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Frequently Asked Questions about UN 2742
UN 2742 is Chloroformates, poisonous, corrosive, flammable, n.o.s., regulated as a hazardous material for transport and emergency response.
The main concern is a hazardous material behavior plus exposure risk from dust, vapor, liquid or fire products.
Approach from upwind, isolate the area, keep nonessential people out and verify the exact product with shipping papers or SDS.
Avoid direct water on the liquid because many chloroformates decompose with heat, HCl and CO2 pressure.
Use SCBA and chemical-protective clothing; Level A is appropriate where vapor concentration, product identity or splash risk is unknown.
Fire can produce toxic acid gases and flammable vapor flashback; downwind control is critical.
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.