Glossary / Physical hazards
Flammable liquid
A flammable liquid is a liquid that gives off ignitable vapor at relatively low temperatures, defined mainly by its flash point. Under DOT, Class 3 flammable liquids have a flash point of not more than 60 C (140 F).
Explanation
It is the vapor, not the liquid, that burns. When enough vapor mixes with air within its flammable range and meets an ignition source, flame can flash back across a room to the container. Acetone, gasoline, ethanol and many paint thinners are everyday examples.
The GHS and OSHA HazCom divide flammable liquids into categories 1 to 4 using flash point and initial boiling point. Category 1 is the most hazardous, with the lowest values, and category 4 the least. These categories drive the signal word, pictogram and hazard statement on the label.
Vapors are usually heavier than air, so they collect in low spots and travel along floors to distant ignition sources. Static electricity during pouring, pumping or filling is a classic ignition source, which is why grounding and bonding are standard controls for transfers.
Control comes from the hierarchy: use less, keep containers closed, ventilate, remove ignition sources, and store in approved cabinets or rooms. Fire codes limit how much can sit outside a cabinet, and the SDS describes suitable extinguishing media.
What to do and watch for
- Keep containers closed and store excess in approved flammable storage cabinets.
- Ground and bond metal containers during transfers.
- Keep hot work, heaters and sparking equipment away from open handling.
Where it appears on an SDS
- Section 2: Hazard identification. Flammable liquid category, flame pictogram, signal word and hazard statements such as H224, H225 or H226.
- Section 9: Physical and chemical properties. Flash point, boiling point and flammable limits, the figures behind the classification.
- Section 5: Fire-fighting measures. Suitable extinguishing media and the specific fire-fighting hazards.
SDS content and wording vary by supplier. This page is general reference and does not replace the current SDS for your product.
Related terms
- Flash point
- Combustible liquid
- Flammable range
- Vapor density
- Grounding and bonding
- Flammable storage cabinet