UN 2664 — Dibromomethane
Placard: Toxic. ERG Guide 160. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2664 is Dibromomethane, a toxic dense halogenated liquid assigned to ERG Guide 160. Low-area vapor and sinking liquid contamination are key concerns.
Hazard overview: TOXIC dense halogenated liquid; ingestion, inhalation of vapor or skin contact may cause injury. Vapors are heavier than air and may cause dizziness or oxygen-displacement risk in confined spaces. Liquid is denser than water and may sink, spreading contamination below the surface.
Response guidance: For UN 2664, isolate the area, avoid skin contact and use SCBA where dust, vapor, mist or fire is present. Control ignition or moisture hazards as applicable and contain toxic/corrosive runoff.
Firefighter training notes: Training for UN 2664 should emphasize toxic exposure routes, SCBA use, dust/vapor monitoring, fire behavior, decontamination, runoff containment and SDS verification. Use ERG 160, SDS and local SOP.
Regulatory context: Dibromomethane 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: Dibromomethane should be stored in tightly closed compatible containers with ventilation, secondary containment, restricted access and SDS-based segregation from incompatible materials.
UN 2664 Quick Details
Common Hazards of UN 2664
- TOXIC dense halogenated liquid; ingestion, inhalation of vapor or skin contact may cause injury.
- Vapors are heavier than air and may cause dizziness or oxygen-displacement risk in confined spaces.
- Liquid is denser than water and may sink, spreading contamination below the surface.
- Non-flammable liquid, but heating or fire may produce hydrogen bromide and toxic brominated fumes.
- Contact may irritate or burn eyes and skin.
- Runoff may carry brominated contamination and harm waterways.
- Containers may rupture or fail when heated.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid with a sweet, chloroform-like odor. Denser than water and will sink.
| Also known as | Methylene dibromideMethylene bromideDibromomethaneDBMMethane dibromide |
| CAS Number | 74-95-3 |
| Appearance | Colorless to pale yellow liquid with a sweet, chloroform-like odor. Denser than water and will sink. |
| Flash Point | Not applicable (non-flammable liquid) |
| Boiling Point | 97C (207F) |
| Vapor Density | 5.8 (heavier than air) |
| Water Reactivity | No significant reaction with water; slightly soluble |
Fireground Response Guidance — UN 2664
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and full chemical protective clothing. Level A may be needed for heavy vapor, splash risk or unknown concentrations; avoid skin contact.
Isolation & Evacuation
First Actions for a UN 2664 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.
- 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 160, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2664 — DibromomethaneUse 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.