Yes. Acetonitrile is highly flammable. It is classified as a Class IB flammable liquid with a flash point of 42°F (5.6°C) and a boiling point of 179°F (81.6°C), per the NIOSH Pocket Guide to Chemical Hazards. Its vapors are heavier than air, can travel to an ignition source, and flash back. Under GHS it carries H225: highly flammable liquid and vapor.
What are acetonitrile’s key flammability numbers?
Acetonitrile (CH₃CN, CAS 75-05-8) ignites readily at ordinary room temperatures. The hard data every EHS manager and buyer should have on file:
| Property | Value | Source |
|---|---|---|
| Flash point | 42°F (5.6°C) | NIOSH |
| Boiling point | 179°F (81.6°C) | NIOSH |
| Autoignition temperature | 975°F (524°C) | USCG / CAMEO |
| Lower explosive limit (LEL) | 3.0% | NIOSH |
| Upper explosive limit (UEL) | 16.0% | NIOSH |
| Vapor density (air = 1) | 1.42 — sinks and spreads | NTP / CAMEO |
| Vapor pressure | 73 mmHg at 68°F | NIOSH |
| Specific gravity | 0.78 | NIOSH |
| NFPA 704 rating | Health 2, Flammability 3, Instability 0 | NFPA via CAMEO |
| DOT shipping | UN1648, Class 3 Flammable Liquid, ERG Guide 127 | DOT/NIOSH |
Why is acetonitrile such a serious fire hazard?
Three reasons. First, its flash point of 42°F means it forms an ignitable vapor at typical warehouse and lab temperatures — no heating required. Second, acetonitrile vapor is 1.42 times heavier than air, so it pools low, travels along floors and trenches to distant ignition sources, and can flash back to the container, per NOAA CAMEO Chemicals. Third, its flammable range is wide: any vapor-air mixture between 3% and 16% acetonitrile can ignite.
How should you store and handle acetonitrile?
Acetonitrile is a Class IB flammable liquid, so it belongs in the same storage program as acetone and ethanol: flammable-liquids storage areas, away from heat and ignition sources, with ventilation that prevents vapor accumulation at floor level. NIOSH lists strong oxidizers as its key incompatibility. During transfers, DOT emergency response guidance (ERG Guide 127) requires eliminating ignition sources and grounding all equipment handling the product — bond and ground drums, pumps, and receiving vessels before you move liquid. Remove wet clothing immediately; it is a flammability hazard.
Practical drum handling is covered in our guide to reading a GHS label on a chemical drum — acetonitrile drums will show the flame pictogram and H225.
What happens when acetonitrile burns?
Acetonitrile fires are doubly dangerous: when heated to decomposition it produces toxic hydrogen cyanide gas and nitrogen oxides. Because acetonitrile is fully miscible with water, ordinary firefighting foam breaks down — ERG Guide 127 calls for dry chemical, CO₂, water spray, or alcohol-resistant foam for small fires, and alcohol-resistant foam for large ones. Straight water streams can spread the burning liquid.
Is acetonitrile toxic as well as flammable?
Yes. Acetonitrile is metabolized to cyanide in the body. The OSHA permissible exposure limit is 40 ppm (70 mg/m³) as an 8-hour TWA under 29 CFR 1910.1000 Table Z-1. NIOSH recommends a lower REL of 20 ppm TWA, and the IDLH value is 137 ppm. Exposure routes include inhalation, skin absorption, ingestion, and eye contact — prevent skin contact and provide quick-drench facilities in transfer areas.
What grades of acetonitrile does RightPath stock?
RightPath Industries supplies acetonitrile as part of our high purity solvents line, including HPLC and analytical grades for chromatography and life-science work — see what HPLC grade acetonitrile means — plus technical grade for industrial extraction and synthesis. Packaging runs from cases and 5-gallon pails through 55-gallon steel drums to totes, depending on grade. Every shipment includes a certificate of analysis and SDS.
How do you order acetonitrile from RightPath?
Tell us your grade, annual volume, and delivery location, and we quote landed cost with freight included. As a stocking distributor we ship drums and totes fast, and we handle the Class 3 flammable-liquid paperwork. Request bulk pricing and our team will respond same business day.
Frequently asked questions
Can acetonitrile vapors really travel to an ignition source?
Yes. With a vapor density of 1.42, acetonitrile vapor is heavier than air. It sinks, accumulates in low spots, and can travel a considerable distance along the ground to an ignition source and flash back to the spill or container.
What DOT hazard class is acetonitrile?
Acetonitrile ships as UN1648, DOT Class 3 Flammable Liquid, with emergency response covered by ERG Guide 127 (water-miscible flammable liquids).
What fire extinguisher works on an acetonitrile fire?
Dry chemical, CO₂, water spray, or alcohol-resistant foam. Standard foams fail because acetonitrile is water-miscible — for large fires use alcohol-resistant foam and cool exposed containers with water.
Does acetonitrile require grounding and bonding during transfer?
Yes. DOT emergency guidance requires all equipment handling acetonitrile to be grounded, and standard flammable-liquid practice is to bond the drum to the receiving vessel before every transfer.
What are the exposure limits for acetonitrile?
OSHA PEL: 40 ppm TWA. NIOSH REL: 20 ppm TWA. IDLH: 137 ppm. Acetonitrile forms cyanide in the body, so treat overexposure as a medical emergency.
When your lab or production line is ready to source certified material, see current availability of HPLC and distilled-in-glass grade acetonitrile from RightPath.
