UN 2709 — Butylbenzenes
Placard: Flammable. ERG Guide 128. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2709 At a Glance
UN 2709 (Butylbenzenes) is listed as DOT Class 3 Flammable and is assigned to ERG Guide 128. Use this page to review placard data, common hazards, PPE notes, isolation context, first actions, and related UN numbers.
Butylbenzenes are flammable aromatic hydrocarbon liquids. Isomer composition may vary, so responders should verify product details on the SDS.
Hazard overview: Butylbenzenes presents a flammable vapor hazard. Vapor can move along surfaces, enter drains or low spots and flash back to the spill or container.
Response guidance: Eliminate ignition sources, isolate the release and keep product out of sewers. Use Alcohol-resistant foam, dry chemical, CO2 and water spray for cooling for fire control, and cool exposed containers from a protected position.
Firefighter training notes: Train crews to identify Butylbenzenes by UN number, placard, ERG guide and SDS before choosing entry, isolation or extinguishment tactics.
Regulatory context: Use UN 2709, ERG 128, SDS, container labels and shipping papers to confirm the exact hazard profile and protective action distances.
Storage & handling: Store in closed, compatible containers away from heat, ignition sources and incompatible materials; keep the area ventilated and protected from damage.
UN 2709 Quick Details
Common Hazards of UN 2709
- Highly flammable liquid; vapors may ignite from heat, sparks, static or open flame.
- Vapors can form explosive mixtures with air and travel to a distant ignition source.
- Heavier-than-air vapors may collect in low areas, confined spaces, drains or sewers.
- Runoff to drains can create fire or vapor explosion hazards.
- Containers exposed to fire may rupture or explode from pressure buildup.
- Liquid contact may irritate skin and eyes; inhalation may cause dizziness or respiratory irritation.
- Fire may produce irritating or toxic smoke.
Chemical Identity & Physical Properties
Clear colorless to pale yellow oily liquid with a weak aromatic hydrocarbon odor; immiscible with water.
| Also known as | n-ButylbenzeneMonobutylbenzenePhenylbutane1-Phenylbutane |
| CAS Number | 104-51-8 |
| Appearance | Clear, colorless to pale yellow liquid with a weak aromatic hydrocarbon odor. Oily consistency, immiscible with water. |
| Flash Point | 47°C (117°F) |
| Boiling Point | 183°C (361°F) |
| Vapor Density | 4.6 (heavier than air) |
| Water Reactivity | No significant reaction; floats on water and can spread a surface fire |
Fireground Response Guidance — UN 2709
Extinguishing Media
PPE Requirements
Use SCBA in vapor areas or fire conditions with chemical-resistant gloves, splash protection and protective clothing.
Isolation & Evacuation
First Actions for a UN 2709 Incident
- Call 911 and the emergency response number shown on shipping papers or container documents.
- Keep unauthorized personnel away and establish an initial isolation perimeter.
- Stay upwind, uphill and upstream; avoid low areas where vapors or runoff may collect.
- Avoid breathing vapors, dust, smoke or mist and prevent skin and eye contact.
- Eliminate ignition sources, stop traffic through vapor areas and keep product out of drains and sewers.
- Do not touch damaged containers or spilled material without appropriate chemical PPE.
- Ventilate confined spaces only when personnel are trained, monitored and properly equipped.
- Use ERG guidance, SDS, shipping papers and air monitoring before committing crews.
📋 Copy & Share Field Card
UN 2709 — ButylbenzenesUse 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.