UN 2621 — Acetyl methyl carbinol
Placard: Flammable. ERG Guide 127. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2621 is Acetyl methyl carbinol, a flammable liquid assigned to ERG Guide 127. 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 2621, isolate the area, eliminate ignition sources when flammable vapors are present and use SCBA. Keep vapors out of drains, cool containers from protection and select foam/dry chemical/CO2 from SDS and ERG 127.
Firefighter training notes: Training for UN 2621 should emphasize vapor travel, sewer flashback, foam selection, ignition control, SCBA use, decontamination, container cooling and runoff containment. Use ERG 127, SDS and local SOP.
Regulatory context: Acetyl methyl carbinol 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: Acetyl methyl carbinol 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 2621 Quick Details
Common Hazards of UN 2621
- 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 carbon monoxide and irritating/toxic smoke.
- Exact isomer or ester composition may affect flash point and exposure hazards; verify SDS.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid with a pleasant, buttery or creamy odor. Liquid at room temperature with a relatively low viscosity.
| Also known as | 3-Hydroxy-2-butanoneAcetoin3-Hydroxybutanone2,3-ButanoloneDimethylketol |
| CAS Number | 513-86-0 |
| Appearance | Colorless to pale yellow liquid with a pleasant, buttery or creamy odor. Liquid at room temperature with a relatively low viscosity. |
| Flash Point | 41°C (106°F) |
| Boiling Point | 148°C (298°F) |
| Vapor Density | 3.0 (heavier than air) |
| Water Reactivity | Soluble in water; no significant reaction |
Fireground Response Guidance — UN 2621
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, smoke, 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 2621 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, gas, 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 127, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2621 — Acetyl methyl carbinolUse 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.