UN 2056 — Tetrahydrofuran
Placard: Flammable. ERG Guide 127. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2056 is Tetrahydrofuran, a highly flammable ether solvent assigned to ERG Guide 127. It can form explosive peroxides during storage, so age and inhibitor status matter.
Hazard overview: HIGHLY FLAMMABLE ether solvent; vapors may ignite easily and form explosive mixtures with air. Vapors are heavier than air and may travel to ignition sources and flash back. May form explosive peroxides during storage, especially when old, inhibited poorly or exposed to air/light.
Response guidance: For a UN 2056 incident, verify the product with shipping papers, container markings, SDS and ERG Guide 127. Establish incident command, isolate the area, stay upwind, control ignition or incompatibility hazards, prevent runoff or vapor spread and base entry/fire-control actions on monitoring and local SOP.
Firefighter training notes: Training for UN 2056 should emphasize flammable vapor travel, sewer flashback, peroxide/drying hazards where applicable, foam selection, container cooling and runoff control. Use ERG 127, SDS and local SOP.
Regulatory context: Tetrahydrofuran 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: Tetrahydrofuran should be stored in approved flammable-liquid containers with ventilation, bonding/grounding where required, spill containment and separation from heat, ignition sources, oxidizers and incompatible materials. For tetrahydrofuran, track inhibitor status, storage age and peroxide testing per facility SOP.
UN 2056 Quick Details
Common Hazards of UN 2056
- HIGHLY FLAMMABLE ether solvent; vapors may ignite easily and form explosive mixtures with air.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- May form explosive peroxides during storage, especially when old, inhibited poorly or exposed to air/light.
- Vapor explosion hazard exists in drains, sewers and confined spaces.
- Runoff to sewers may create fire or explosion hazards.
- Containers may rupture or explode when heated.
- Fire may produce irritating and/or toxic gases.
Chemical Identity & Physical Properties
Colorless liquid with a sweet, ether-like odor. Highly volatile and mobile at room temperature.
| Also known as | THF1,4-EpoxybutaneTetramethylene oxideDiethylene oxideOxacyclopentane |
| CAS Number | 109-99-9 |
| Appearance | Colorless liquid with a sweet, ether-like odor. Highly volatile and mobile at room temperature. |
| Flash Point | -14°C (7°F) |
| Boiling Point | 66°C (151°F) |
| Vapor Density | 2.5 (heavier than air) |
| Water Reactivity | Miscible with water; no significant reaction under normal conditions |
Fireground Response Guidance — UN 2056
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, fire or confined-space exposure. Wear chemical-resistant gloves, eye/face protection, flame-resistant protection as appropriate and PPE selected from SDS.
Isolation & Evacuation
First Actions for a UN 2056 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, gas, dust, mist, smoke or fumes and avoid skin or eye contact.
- Eliminate ignition sources if safe and keep vapors and runoff out of drains, sewers, basements and low areas.
- Do not touch damaged containers or spilled/released material unless properly trained and wearing appropriate protective equipment.
- 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, gas accumulation, cylinder heating or unknown product identity.
- Use ERG Guide 127, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 2056 — TetrahydrofuranUse 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.