UN 2605 — Methoxymethyl isocyanate
Placard: Toxic. ERG Guide 155. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2605 is Methoxymethyl isocyanate, a toxic flammable isocyanate assigned to ERG Guide 155. Respiratory sensitization, vapor flashback and water reaction are key concerns.
Hazard overview: TOXIC and FLAMMABLE isocyanate liquid; inhalation of vapor or aerosol may cause severe respiratory sensitization. Vapors may ignite and form explosive mixtures with air. Reacts with water to release carbon dioxide, heat and polymeric solids; pressure buildup may occur in closed containers.
Response guidance: For UN 2605, isolate the area, eliminate ignition sources where relevant and use SCBA with chemical protection. Control water contact, contain toxic/corrosive runoff and choose agents using SDS and ERG 155.
Firefighter training notes: Training for UN 2605 should emphasize water/moisture reaction, toxic/corrosive vapor control, SCBA use, foam/dry-agent choice, decontamination and runoff containment. Use ERG 155, SDS and local SOP.
Regulatory context: Methoxymethyl isocyanate 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: Methoxymethyl isocyanate should be stored in tightly closed compatible containers in a cool, dry, ventilated area away from water/moisture, amines, alcohols, acids/bases where incompatible and heat.
UN 2605 Quick Details
Common Hazards of UN 2605
- TOXIC and FLAMMABLE isocyanate liquid; inhalation of vapor or aerosol may cause severe respiratory sensitization.
- Vapors may ignite and form explosive mixtures with air.
- Reacts with water to release carbon dioxide, heat and polymeric solids; pressure buildup may occur in closed containers.
- Skin and eye contact may cause irritation, burns or sensitization.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- Fire may produce nitrogen oxides, isocyanate vapors and hydrogen cyanide-type toxic gases.
- Runoff may spread toxic isocyanate contamination.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid with a pungent, acrid odor. Highly reactive organic compound in the isocyanate family.
| Also known as | Methoxymethyl isocyanateMMICIsocyanic acid methoxymethyl esterMethoxymethanyl isocyanate |
| CAS Number | 39815-82-4 |
| Appearance | Colorless to pale yellow liquid with a pungent, acrid odor. Highly reactive organic compound in the isocyanate family. |
| Flash Point | -7C (19F) |
| Boiling Point | 85-90C (185-194F) |
| Vapor Density | 2.5 (heavier than air) |
| Water Reactivity | Reacts with water to release carbon dioxide and heat; avoid contact with moisture |
Fireground Response Guidance — UN 2605
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and chemical-resistant protective clothing. Level A may be needed for heavy vapor, fuming, splash risk or unknown concentrations.
Isolation & Evacuation
First Actions for a UN 2605 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.
- Keep water or moisture contact controlled when it may increase reaction, fuming or gas generation.
- 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 155, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2605 — Methoxymethyl isocyanateUse 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.