The short answer is yes: m-xylene (CAS 108-38-3) is a flammable liquid, and it must be stored and handled with that fact in mind at all times. Its flash point of about 25 °C means it can produce ignitable vapor at ordinary room temperature, and because its vapors are heavier than air, a fire can flash back from an ignition source far from the container. Understanding the numbers behind that hazard is the first step to safe use.
Hazard numbers at a glance:
Flash point: about 25 °C (closed cup) - ignitable vapor forms near room temperature.
Flammable range: roughly 1.1% to 7.0% by volume in air.
Auto-ignition temperature: about 527 °C - high, but hot surfaces and sparks can still ignite vapor.
Vapor density: about 3.7 (air = 1) - vapors sink and travel along floors to ignition sources.
Key Fire and Physical Data
| Property | Value |
| CAS number | 108-38-3 |
| Molecular formula | C8H10 |
| Molecular weight | 106.17 g/mol |
| Boiling point | 139 °C |
| Flash point | About 25 °C (closed cup) |
| Density | 0.864 g/cm3 at 20 °C |
| Vapor density | 3.7 (air = 1) |
| Flammable limits | About 1.1% - 7.0% by volume |
Safe Storage and Handling
Store m-xylene in sealed containers in a cool, dry, well-ventilated area, away from direct sunlight, heat sources, open flames and oxidizers. Use approved flammable-liquid storage cabinets or dedicated bunded areas for drums. Ground and bond containers during transfer to prevent static discharge, and keep only the quantity needed for the shift in the work area. Never smoke near storage or dispensing points.
PPE and Exposure Control
Handle m-xylene with chemically resistant gloves, safety goggles and protective clothing, and use local exhaust ventilation where vapor can accumulate. Avoid inhaling vapors and skin contact. Occupational exposure limits are set by national regulations (for example, TLVs published by ACGIH), and airborne monitoring is recommended where m-xylene is used regularly. Wash hands before eating or smoking, and do not pour residues down drains.
Spill and Emergency Response
If a leak occurs, evacuate the immediate area, eliminate ignition sources and ventilate. Contain the liquid with absorbent materials designed for hydrocarbons, transfer it to suitable waste containers, and prevent any entry into drains, soil or waterways. For a fire, use dry chemical, carbon dioxide or alcohol-resistant foam - water spray can cool exposed containers but should not be used directly on burning liquid. In all cases, follow your site emergency plan and local regulations.
Transport Classification
m-Xylene is a Class 3 flammable liquid transported as UN 1307, Packing Group III. Shipping documentation, labels and vehicle requirements follow the applicable road, rail, sea and air regulations. GHS labels carry H226 (flammable liquid and vapor), H315, H319, H332 and H335 hazard statements. Always confirm the current classification on the SDS for your jurisdiction and transport mode.
Frequently Asked Questions
At what temperature does m-xylene catch fire? Its flash point is about 25 °C, meaning vapor above the liquid can ignite near room temperature. Auto-ignition without a flame or spark requires roughly 527 °C.
Is m-xylene vapor heavier than air? Yes, about 3.7 times heavier than air, so vapors flow along the ground and can travel to distant ignition sources, causing flashback fires.
Can m-xylene explode? In vapor form within its flammable range (about 1.1% - 7.0%), it can ignite explosively in confined spaces. Good ventilation and vapor detection reduce this risk.
What class of dangerous good is m-xylene? It is a Class 3 flammable liquid, UN 1307, Packing Group III.
How should m-xylene be stored? In sealed, correctly labeled containers in a cool, dry, ventilated area, away from heat, flames, sunlight and oxidizers, preferably in flammable-liquid storage cabinets.
What extinguisher works on an m-xylene fire? Dry chemical, carbon dioxide or alcohol-resistant foam are suitable. Do not use a direct water jet on burning liquid.