UN 2826 — Ethyl chlorothioformate
Placard: Corrosive. ERG Guide 155. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2826 is Ethyl chlorothioformate, a flammable toxic corrosive chlorothioformate assigned to ERG Guide 155. Water reaction and flashback are key hazards.
Hazard overview: HIGHLY FLAMMABLE, TOXIC and CORROSIVE chlorothioformate liquid; vapors may ignite easily. Reacts with water or moist air, releasing hydrogen chloride and sulfur-containing toxic/corrosive gases. Vapors are heavier than air and may travel to ignition sources and flash back.
Response guidance: For UN 2826, isolate the spill, stay upwind and use SCBA with chemical protection. Control moisture contact, use compatible dry agents and contain acidic/toxic runoff under ERG 155.
Firefighter training notes: Training for UN 2826 should emphasize moisture-reactive corrosive fuming, dry-agent choice, SCBA/Level A decisions, decontamination and acidic runoff control. Use ERG 155, SDS and local SOP.
Regulatory context: Ethyl chlorothioformate is regulated as a hazardous material for transport and emergency response. Storage, exposure, spill reporting, waste and fire-code duties depend on quantity, concentration and jurisdiction; verify shipping papers, SDS and local authority requirements.
Storage & handling: Ethyl chlorothioformate should be stored dry in tightly closed compatible containers away from water, moisture, bases, alcohols/amines where incompatible, heat and unauthorized access.
UN 2826 Quick Details
Common Hazards of UN 2826
- HIGHLY FLAMMABLE, TOXIC and CORROSIVE chlorothioformate liquid; vapors may ignite easily.
- Reacts with water or moist air, releasing hydrogen chloride and sulfur-containing toxic/corrosive gases.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- Liquid and vapor can burn eyes, skin and respiratory tissue.
- Fire may produce hydrogen chloride, sulfur oxides, phosgene-type gases and other toxic smoke.
- Runoff may be acidic, toxic and flammable-contaminated.
- Containers may rupture or explode when heated or contaminated with water.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid with a pungent, irritating odor. Liquid at room temperature.
| Also known as | Ethyl chlorothionoformateChlorothioformic acid ethyl esterEthoxycarbonothioyl chlorideEthyl chlorocarbonothioate |
| CAS Number | 2941-64-2 |
| Appearance | Colorless to pale yellow liquid with a pungent, irritating odor. Liquid at room temperature. |
| Flash Point | -7C (19F) |
| Boiling Point | 137-139C (279-282F) |
| Vapor Density | 3.3 (heavier than air) |
| Water Reactivity | Reacts with water and moisture, releasing HCl and toxic gases; avoid water contact |
Fireground Response Guidance — UN 2826
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and chemical-resistant protective clothing. Level A may be needed for heavy vapor, splash, fuming or unknown concentrations.
Isolation & Evacuation
First Actions for a UN 2826 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind, uphill and upstream.
- Eliminate ignition sources if this can be done safely.
- Keep water or moisture contact controlled because reaction or re-ignition hazards may be severe.
- Avoid breathing vapor, dust, mist, smoke or fumes and avoid skin or eye contact.
- Do not touch damaged containers or spilled material without proper training and PPE.
- Prevent contaminated liquid, dust, runoff and decontamination waste from spreading.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 155, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2826 — Ethyl chlorothioformateUse for: Quick radio or face-to-face size-up. Short, structured, field-ready.
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
Use for: Quick text to command or incoming units. Fits in a single SMS.