UN 1648 — Acetonitrile
Placard: Flammable. ERG Guide 127. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1648 is Acetonitrile, a Class 3 flammable liquid assigned to ERG Guide 127. It is water-miscible, toxic and capable of forming explosive vapor-air mixtures.
Hazard overview: UN 1648 presents flammable vapor, flashback, vapor explosion and toxic exposure hazards. Vapors can travel to ignition sources, and fire may produce hydrogen cyanide and nitrogen oxides.
Response guidance: For a UN 1648 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 127. Establish incident command, isolate the area, stay upwind, prevent dust or vapor exposure, control runoff and choose entry or cleanup actions based on monitoring, SDS and local SOP.
Firefighter training notes: Training for UN 1648 should emphasize flammable vapor control, sewer vapor explosion risk, toxic nitrile exposure, water-miscible runoff and foam compatibility. Use ERG 127, SDS and local SOP.
Regulatory context: Acetonitrile 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, concentration, 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: Acetonitrile should be stored in compatible flammable-liquid storage away from heat, ignition sources, oxidizers, acids/bases where incompatible and unauthorized access. Use ventilation, bonding/grounding where required and spill containment for water-miscible toxic liquid.
UN 1648 Quick Details
Common Hazards of UN 1648
- HIGHLY FLAMMABLE liquid; vapors may ignite easily and form explosive mixtures with air.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- Vapor explosion hazard exists indoors, outdoors, in sewers and in confined spaces.
- Toxic exposure may occur by inhalation, ingestion or skin contact; fire may produce hydrogen cyanide and nitrogen oxides.
- Runoff to sewers may create fire, explosion and toxic contamination hazards.
- Containers may rupture or explode when heated.
- Water miscibility can spread contaminated flammable liquid if runoff is not controlled.
Chemical Identity & Physical Properties
Clear, colorless liquid with a distinctive sweet, ether-like odor. Miscible with water and most organic solvents.
| Also known as | Methyl cyanideCyanomethaneEthanenitrileMethane carbonitrile |
| CAS Number | 75-05-8 |
| Appearance | Clear, colorless liquid with a distinctive sweet, ether-like odor. Miscible with water and most organic solvents. |
| Flash Point | 2C (36F) |
| Boiling Point | 82C (180F) |
| Vapor Density | 1.4 (heavier than air) |
| Water Reactivity | Miscible with water; no violent reaction but forms flammable mixtures |
Fireground Response Guidance — UN 1648
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, fire or confined-space exposure. Chemical-resistant gloves, eye/face protection and protective clothing should be selected from SDS; vapor control and ignition control are both important.
Isolation & Evacuation
First Actions for a UN 1648 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, fumes, dust or mist and avoid all skin or eye contact.
- Eliminate ignition sources if it is safe to do so and keep vapors out of drains, sewers and low areas.
- Do not touch or walk through spilled material unless properly trained and wearing appropriate protective equipment.
- Avoid creating dust clouds or spreading contaminated liquid, powder, solution, runoff or debris.
- Ventilate closed spaces before entering, but only if properly trained, equipped, monitored and authorized by incident command.
- Isolate the spill or leak area and expand the perimeter if dust, vapor, fire involvement or unknown concentration is present.
- Use ERG Guide 127, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1648 — AcetonitrileUse 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.