autoignitiontemperaturen

Autoignition temperature refers to the lowest temperature at which a material will ignite spontaneously in air without an external ignition source, under specified testing conditions. It is commonly abbreviated as AIT and used to describe the propensity of a substance to self-ignite when heated.

AIT depends on several factors, including the chemical composition and physical form of the material, as well as environmental conditions. In general, higher oxygen concentration lowers the autoignition temperature, while changes in ambient pressure and airflow can raise or lower results. The heating rate, particle size or surface area, moisture content, and the presence of impurities all influence the measured AIT. For solids and liquids, practical values can differ widely between substances and even with the same substance under different test setups.

The concept is distinct from the flash point, which is the lowest temperature at which enough vapor is produced to form an ignitable mixture with an external ignition source. Autoignition requires no such ignition source and is concerned with self-heating to the point of ignition.

Measurement of AIT is typically performed using standardized tests that gradually heat a sample in air and monitor for sustained ignition. Test conditions are defined for temperature ramp, sample mass, atmosphere, and ignition criteria, and results are usually reported for a reference condition such as air at approximately one atmosphere.

AIT is used in safety engineering and risk assessment to classify materials, design storage and processing controls, and evaluate the hazards associated with heating or handling materials. It is one of several factors, alongside flash point and flammability limits, considered in fire and explosion safety.