UN 2664 — Dibromomethane
Placard: Toxic. ERG Guide 160. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2664 At a Glance
UN 2664 (Dibromomethane) is listed as DOT Class 6 Toxic and is assigned to ERG Guide 160. Use this page to review placard data, common hazards, PPE notes, isolation context, first actions, and related UN numbers.
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.