flammability

Flammability is the property of a material to ignite and sustain combustion. It depends on chemical composition, physical state, temperature, and the presence of an ignition source and an oxidizer, typically atmospheric oxygen. Materials are commonly categorized as flammable or extremely flammable, combustible, or non-flammable.

Key concepts used to assess flammability include the flash point, autoignition temperature, and flammable limits. The lower flammable limit (LFL) is the minimum vapor concentration required for ignition, while the upper flammable limit (UFL) is the maximum concentration. The autoignition temperature is the minimum temperature at which a material will ignite without an external flame. Gases may form an explosive mixture with air within their flammable range. Flammability is evaluated using standardized tests and measurements, such as flash point determinations and vapor pressure assessments, to determine hazards and appropriate handling.

Safety and handling practices aim to reduce ignition risk and control exposure. This includes minimizing ignition sources, ensuring proper ventilation, grounding and bonding to prevent static discharge, and storing flammable materials in approved containers and locations away from oxidizers and heat sources. Regulatory frameworks and labeling systems, such as NFPA hazard ratings and GHS pictograms, communicate flammability hazards and guide risk management in workplaces and transport.

In everyday use, solvents, fuels, and aerosols often present higher flammability risk, while solids like wood are combustible but may be non-flammable when treated. Flammability remains a central concern in occupational safety, fire protection engineering, and environmental protection.