UN 1265 — Isopentane
Placard: Flammable. ERG Guide 128. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1265 is Isopentane, a Class 3 flammable hydrocarbon liquid assigned to ERG Guide 128. It can produce heavy vapors, flashback hazards and floating fuel fires if spilled near water or drains.
Hazard overview: UN 1265 presents hydrocarbon vapor, surface-spread fire and environmental runoff hazards. Vapors may collect in low or sewer areas, and floating liquid can carry fire across water surfaces.
Response guidance: For a UN 1265 incident, responders should confirm the product using shipping papers, container markings, SDS and ERG Guide 128. Establish incident command, isolate the area, stay upwind and uphill, remove ignition sources when safe, keep vapors or runoff out of sewers and use compatible fire-control agents from a protected position.
Firefighter training notes: Training for UN 1265 should emphasize hydrocarbon vapor travel, flashback, surface-spreading fuel, sewer vapor explosion risk, foam use and runoff control. Use ERG 128, SDS and local SOP.
Regulatory context: Isopentane is regulated as a hazardous material for transportation and emergency response purposes. Transportation, workplace exposure, spill reporting, waste handling, storage and environmental requirements may vary by formulation, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Isopentane should be stored in tightly closed compatible containers in a cool, dry, well-ventilated flammable-liquid storage area. Keep away from heat, sparks, open flames, oxidizers and incompatible materials, with bonding/grounding, secondary containment and drain protection where required.
UN 1265 Quick Details
Common Hazards of UN 1265
- FLAMMABLE hydrocarbon liquid; may be ignited by heat, sparks or flames.
- Vapors may form explosive mixtures with air, especially when heated or aerosolized.
- Vapors are heavier than air and may collect in low, confined or sewer areas.
- Liquid floats on water and may spread fire across surfaces.
- Runoff to sewer or waterways may create fire and environmental hazards.
- Fire may produce irritating or toxic smoke.
- Containers or tanks may rupture or explode when heated.
Chemical Identity & Physical Properties
Colorless liquid with a gasoline-like or petroleum-like odor. Highly volatile at room temperature.
| Also known as | 2-MethylbutaneIsoamylhydrideEthyldimethylmethane2-Methyl-butane |
| CAS Number | 78-78-4 |
| Appearance | Colorless liquid with a gasoline-like or petroleum-like odor. Highly volatile at room temperature. |
| Flash Point | -51C (-60F) |
| Boiling Point | 28C (82F) |
| Vapor Density | 2.5 (heavier than air) |
| Water Reactivity | No significant reaction; insoluble in water and floats on surface |
Fireground Response Guidance — UN 1265
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for fire, heavy vapor or confined-space exposure. Chemical-resistant gloves, splash protection and protective clothing should be selected from SDS; avoid skin contact with liquid and contaminated runoff.
Isolation & Evacuation
First Actions for a UN 1265 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.
- Eliminate ignition sources if it is safe to do so.
- Do not touch or walk through spilled liquid unless properly trained and wearing appropriate protective equipment.
- Ventilate closed spaces before entering, but only if properly trained, equipped and authorized by incident command.
- Isolate the spill or leak area for at least 50 meters (150 feet) in all directions.
- For large spills, fire involvement or strong vapor movement, expand isolation and consider downwind evacuation based on monitoring and incident command.
- Use ERG Guide 128, shipping papers, SDS and local SOP for protective actions and entry decisions.
📋 Copy & Share Field Card
UN 1265 — IsopentaneUse 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.