UN 2321 — Trichlorobenzenes, liquid
Placard: Toxic. ERG Guide 153. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2321 is Trichlorobenzenes, liquid, a toxic chlorinated aromatic liquid assigned to ERG Guide 153. It is persistent, combustible and can produce toxic chlorinated smoke in fire.
Hazard overview: TOXIC chlorinated aromatic liquid; inhalation, ingestion or skin contact may cause injury. Combustible material: may burn but does not ignite readily. Vapors are much heavier than air and may collect in low or confined areas when heated.
Response guidance: For a UN 2321 incident, verify the product with shipping papers, container markings, SDS and ERG Guide 153. Establish incident command, isolate the area, stay upwind, control ignition or incompatibility hazards, prevent runoff, dust or vapor spread and base entry/fire-control actions on monitoring and local SOP.
Firefighter training notes: Training for UN 2321 should emphasize toxic/corrosive exposure routes, contaminated clothing, toxic fire products, decontamination waste and runoff containment. Use ERG 153, SDS and local SOP.
Regulatory context: Trichlorobenzenes, liquid is regulated as a hazardous material for transportation and emergency response purposes. Storage, workplace exposure, emergency planning, spill reporting, waste handling and environmental requirements vary by exact product, concentration, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, container markings and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Trichlorobenzenes, liquid should be stored in tightly closed compatible containers in a secure toxic/corrosive-material area with secondary containment, restricted access, ventilation and waste/decontamination planning according to SDS.
UN 2321 Quick Details
Common Hazards of UN 2321
- TOXIC chlorinated aromatic liquid; inhalation, ingestion or skin contact may cause injury.
- Combustible material: may burn but does not ignite readily.
- Vapors are much heavier than air and may collect in low or confined areas when heated.
- Fire may produce hydrogen chloride, phosgene-type gases and other toxic chlorinated smoke.
- Liquid is insoluble and may form a separate layer, spreading environmental contamination.
- Runoff may pollute waterways and contaminate soil/equipment.
- Avoid all skin contact and control decontamination waste.
Chemical Identity & Physical Properties
Colorless to pale yellow oily liquid with a characteristic aromatic odor. Exists as mixed isomers (1,2,3-, 1,2,4-, and 1,3,5-trichlorobenzene) at room temperature.
| Also known as | TCBTrichlorobenzeneChlorinated benzeneTrichlorbenzolMixed trichlorobenzene isomers |
| Appearance | Colorless to pale yellow oily liquid with a characteristic aromatic odor. Exists as mixed isomers (1,2,3-, 1,2,4-, and 1,3,5-trichlorobenzene) at room temperature. |
| Flash Point | 105-110°C (221-230°F) |
| Boiling Point | 213-219°C (415-426°F) depending on isomer |
| Vapor Density | 6.26 (much heavier than air) |
| Water Reactivity | Insoluble in water; no significant reaction with water |
Fireground Response Guidance — UN 2321
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, dust, mist, fire or confined-space exposure. Wear chemical-resistant gloves, boots, eye/face protection and protective clothing selected from SDS; avoid all skin contact.
Isolation & Evacuation
First Actions for a UN 2321 Incident
- CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Avoid breathing vapors, dust, mist, smoke or fumes and avoid skin or eye contact.
- Do not touch damaged containers or spilled material unless properly trained and wearing appropriate protective equipment.
- Prevent contaminated liquid, dust, residues, runoff and decontamination waste from spreading.
- Ventilate closed spaces before entering, but only if properly trained, equipped, monitored and authorized by incident command.
- Isolate the spill or release area and expand the perimeter for fire involvement, vapor spread, dust generation, water reaction or unknown product identity.
- Use ERG Guide 153, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 2321 — Trichlorobenzenes, liquidUse 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.