flammpunkt

Flammpunkt, commonly translated as flash point, is the lowest temperature at which a liquid emits sufficient vapors to form an ignitable mixture with air at the surface. At or above the flash point, an ignition source such as a flame or spark can cause a brief flame; below it, the vapor concentration is too low to ignite. The flash point does not measure how readily a liquid will sustain burning once ignited, nor does it indicate autoignition temperature.

Measurement relies on standardized tests. The most common methods are open-cup and closed-cup tests. Open-cup methods, where the sample is exposed to air, tend to give lower flash-point values; closed-cup methods trap vapors and usually yield higher values. Closed-cup tests include the Pensky-Martens and Tag closed-cup procedures, while open-cup tests include the Cleveland Open Cup. Results are reported as the liquid’s flash point and are used for safety data sheets, labeling, storage and transport classifications, and risk assessment.

In practice, the flash point helps determine flammability hazards. Liquids with low flash points are considered highly flammable and require stringent controls such as proper ventilation, grounding, surface separation from ignition sources, and appropriate fire-fighting equipment. The flash point is used together with other properties, such as boiling point and autoignition temperature, to categorize hazards and guide handling and regulatory compliance.