UN 1089 — Acetaldehyde
Placard: Flammable. ERG Guide 129P. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1089 is Acetaldehyde, an extremely flammable volatile liquid assigned to ERG Guide 129P. Vapor flashback and polymerization risk require control.
Hazard overview: EXTREMELY FLAMMABLE volatile liquid; vapors may form explosive mixtures with air. Vapors are heavier than air and may travel to ignition sources and flash back. May polymerize if heated or contaminated with acids, bases or oxidizers.
Response guidance: For UN 1089, isolate the area, eliminate ignition sources and keep vapors out of drains. Cool containers, monitor polymerization risk and contain runoff under ERG 129P.
Firefighter training notes: Training for UN 1089 should emphasize flammable vapor control, polymerization warning signs, container cooling, SCBA use, decontamination and runoff control. Use ERG 129P, SDS and local SOP.
Regulatory context: Acetaldehyde is regulated as a hazardous material for transport and emergency response. Storage, reporting, exposure, waste and incident-notification duties depend on quantity, concentration, package type and jurisdiction; verify shipping papers, SDS and authority guidance.
Storage & handling: Acetaldehyde should be stored cool in approved flammable-liquid containers away from ignition sources, heat, oxidizers and polymerization triggers; maintain inhibitor/stabilizer controls where applicable.
UN 1089 Quick Details
Common Hazards of UN 1089
- EXTREMELY FLAMMABLE volatile liquid; vapors may form explosive mixtures with air.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- May polymerize if heated or contaminated with acids, bases or oxidizers.
- Vapor exposure can irritate eyes and respiratory tract and may cause dizziness or nausea.
- Containers may rupture or explode when heated.
- Fire may produce carbon monoxide and irritating/toxic smoke.
- Runoff to drains or sewers may create fire or explosion hazards.
Chemical Identity & Physical Properties
Acetaldehyde physical appearance should be verified from SDS, package labels and shipping papers.
| Also known as | EthanalAcetic aldehydeEthyl aldehyde |
| CAS Number | 75-07-0 |
| Flash Point | -38°C (-36°F) |
| Boiling Point | 20.2°C (68°F) |
| Vapor Density | 1.5 |
Fireground Response Guidance — UN 1089
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, fire or confined-space exposure. Wear chemical-resistant gloves, eye/face protection and protective clothing.
Isolation & Evacuation
First Actions for a UN 1089 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.
- Watch for polymerization, container heating or pressure buildup.
- Avoid breathing vapor, gas, 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, runoff and decontamination waste from spreading.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 129P, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 1089 — AcetaldehydeUse 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.