☣️ UN 2740 • CLASS 6
UN 2740 — n-Propyl chloroformate
Placard: Toxic. ERG Guide 155. 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.
n-Propyl chloroformate is a flammable toxic chloroformate. Moisture contact can create corrosive fumes and pressure in containers.
Hazard overview: This material combines flammable vapor behavior with corrosive/toxic decomposition. Water or humid air can release HCl and CO2, creating pressure and acidic fumes.
Response guidance: Isolate the area, eliminate ignition sources and keep water out of the product. Use dry chemical, CO2 or alcohol-resistant foam; cool intact containers from a protected distance.
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UN 2740 Quick Details
UN 2740
Product name: n-Propyl chloroformate
DOT Class: 6
Placard type: Toxic
ERG Guide: 155 (check current ERG)
Initial isolation: ERG 155: Isolate spill 50m in all directions. Evacuate 300m downwind if tank/rail car involved in fire.
Common Hazards of UN 2740
- n-Propyl chloroformate is highly flammable and toxic by inhalation or skin contact.
- Vapors can form explosive mixtures with air and may flash back from low areas.
- Moisture or water can decompose the liquid, releasing hydrogen chloride, carbon dioxide and heat.
- Closed or contaminated containers may pressurize and rupture.
- Liquid and vapor are corrosive to eyes, skin and respiratory tissue.
- Fire can produce hydrogen chloride, phosgene-like carbonyl chloride products and other toxic gases.
- Runoff may be acidic, toxic and flammable.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid with a pungent, irritating odor. Fuming liquid that reacts with moisture in air
| Also known as | propyl chlorocarbonatepropyl chloroformatechloroformic acid propyl estercarbonochloridic acid propyl ester |
| CAS Number | 109-61-5 |
| Appearance | Colorless to pale yellow liquid with a pungent, irritating odor. Fuming liquid that reacts with moisture in air. |
| Flash Point | 15°C (59°F) |
| Boiling Point | 105-107°C (221-225°F) |
| Vapor Density | 4.2 (heavier than air) |
| Water Reactivity | Reacts violently with water, liberating HCl and CO2. Do not use water directly on material. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 2740
Extinguishing Media
Dry chemical, CO2, or dry sand. Alcohol-resistant foam may be used at a distance. Avoid water spray directly on liquid.
PPE Requirements
⚠️ Level B minimum recommended. Full-face SCBA, chemical-resistant suit. Material is corrosive and toxic by inhalation.
Use SCBA and chemical-protective clothing resistant to acid chloride/chloroformate liquids; Level A may be needed for unknown vapor concentrations.
Isolation & Evacuation
ERG 155: Isolate spill 50m in all directions. Evacuate 300m downwind if tank/rail car involved in fire.
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 155).
First Actions for a UN 2740 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.
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📋 Copy & Share Field Card
UN 2740 — n-Propyl chloroformateHAZMAT RADIO NOTE — UN 2740
Product: n-Propyl chloroformate
Class 6 / Toxic / ERG 155
PPE: Level B minimum recommended. Full-face SCBA, chemical-resistant suit. Material is corrosive and toxic by inhalation.
ISOLATION: ERG 155: Isolate spill 50m in all directions. Evacuate 300m 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 2740 — n-Propyl chloroformate
Class: 6 | Placard: Toxic | ERG Guide: 155
Appearance: Colorless to pale yellow liquid with a pungent, irritating odor. Fuming liquid that reacts with moisture in air.
Water Reactivity: Reacts violently with water, liberating HCl and CO2. Do not use water directly on material.
Extinguishing: Dry chemical, CO2, or dry sand. Alcohol-resistant foam may be used at a distance. Avoid water spray directly on liquid.
PPE: Level B minimum recommended. Full-face SCBA, chemical-resistant suit. Material is corrosive and toxic by inhalation.
Isolation: ERG 155: Isolate spill 50m in all directions. Evacuate 300m downwind if tank/rail car involved in fire.
— Key Hazards —
• n-Propyl chloroformate is highly flammable and toxic by inhalation or skin contact.
• Vapors can form explosive mixtures with air and may flash back from low areas.
• Moisture or water can decompose the liquid, releasing hydrogen chloride, carbon dioxide and heat.
— 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/n-propyl-chloroformate-un-2740 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN2740 n-Propyl chloroformate Cls6 ERG155 | allfirefighter.com/hazmat/un/n-propyl-chloroformate-un-2740SMS / 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/n-propyl-chloroformate-un-2740
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Frequently Asked Questions about UN 2740
UN 2740 is n-Propyl chloroformate, 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 contact with the liquid; moisture can release HCl, heat and carbon dioxide pressure.
Use SCBA and chemical-protective clothing resistant to acid chloride/chloroformate liquids; Level A may be needed for unknown vapor concentrations.
Fire may produce toxic HCl and carbonyl chloride-type gases while vapors can flash back.
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.