nonflammable

Nonflammable describes materials that do not ignite or sustain combustion under normal conditions. The term is commonly used in safety data sheets, product labeling, and regulatory contexts to distinguish these substances from flammable materials, which can ignite easily in air.

The exact criteria for nonflammability depend on standards and definitions that vary by jurisdiction and material type. A liquid may be labeled nonflammable if its flash point is above a specified threshold, or if it does not form flammable vapors in air under standard conditions. Gases may be considered nonflammable if they do not form combustible mixtures with air at ordinary temperatures and pressures. For solids, nonflammable generally means the material itself will not ignite or propagate flame when exposed to a flame or high heat. It is important to note that nonflammable does not guarantee complete fire safety in all circumstances.

Nonflammable is often contrasted with noncombustible, a term used in building codes and standards. Noncombustible materials are those that do not ignite in air and do not contribute to flame spread. In some contexts, the terms are used interchangeably, but language differences can lead to confusion, so specific definitions in a given standard should be consulted.

Examples of commonly nonflammable materials include water, sand, glass, concrete, and many metals. Some materials that are nonflammable under normal conditions can still pose risks under extreme heat, decomposition, or in the presence of oxidizers, and may produce hazardous gases or dust explosions. Appropriate handling, storage, and ventilation remain important even for nonflammable substances.