UN 2524 — Ethyl orthoformate
Placard: Flammable. ERG Guide 129. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2524 is Ethyl orthoformate, a flammable liquid assigned to ERG Guide 129. Heavy vapors can travel to ignition sources and flash back.
Hazard overview: FLAMMABLE liquid; vapors may ignite and form explosive mixtures with air. Vapors are heavier than air and may travel to ignition sources and flash back. Vapor explosion hazard exists in drains, sewers, basements and confined areas.
Response guidance: For UN 2524, isolate the area, eliminate ignition sources, keep vapors out of drains and use SCBA in vapor or fire conditions. Select foam, dry chemical or CO2 using SDS and ERG 129.
Firefighter training notes: Training for UN 2524 should emphasize vapor travel, sewer flashback, foam selection, ignition control, container cooling, SCBA use and runoff containment. Use ERG 129, SDS and local SOP.
Regulatory context: Ethyl orthoformate 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 orthoformate should be stored in approved compatible containers with ventilation, secondary containment and separation from heat, ignition sources, oxidizers and incompatible materials according to SDS.
UN 2524 Quick Details
Common Hazards of UN 2524
- FLAMMABLE liquid; vapors may ignite and form explosive mixtures with air.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- Vapor explosion hazard exists in drains, sewers, basements and confined areas.
- Liquid may float or form a separate layer on water, spreading fire or contamination.
- Runoff to sewers may create fire or explosion hazards.
- Fire may produce irritating and/or toxic smoke, including halogen acids where applicable.
- Containers may rupture or explode when heated.
Chemical Identity & Physical Properties
Colorless liquid with a pungent, rum-like or fruity odor. Liquid at room temperature.
| Also known as | Triethyl orthoformateTriethoxymethaneEthyl orthoformiateOrthoformic acid triethyl ester |
| CAS Number | 122-51-0 |
| Appearance | Colorless liquid with a pungent, rum-like or fruity odor. Liquid at room temperature. |
| Flash Point | -20°C (-4°F) |
| Boiling Point | 145-146°C (293-295°F) |
| Vapor Density | 5.1 (heavier than air) |
| Water Reactivity | Reacts slowly with water to form ethanol and formic acid; reaction accelerates with acids or heat |
Fireground Response Guidance — UN 2524
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, fire or confined-space exposure. Wear chemical-resistant gloves, eye/face protection and flame-resistant protection as appropriate.
Isolation & Evacuation
First Actions for a UN 2524 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.
- 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.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 129, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2524 — Ethyl orthoformateUse 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.