2   Autogenous ignition temperature (AIT) in high pressure oxygen

For testing, solid materials are divided and liquids are applied onto ceramic fibers. A sample tube that contains a sample mass of ca. 0.1 g to 0.5 g is placed into an autoclave of 34 cm³ in volume. A low-frequency heater allows to heat the sample inductively in an almost linear way at a rate of 110 °C/min.

A thermocouple on the bottom of the sample tube measures the temperature. The pressure is measured by means of a pressure transducer.

The ignition of the sample can be recognized by a sudden rise in temperature and pressure.

Usually, the maximum use temperature of the sample is fixed at a value that is 100 °C below the determined AIT. This safety margin considers the fact, that the AIT is not a constant and depends on test method, sample preparation, and other parameters. Publications in literature as well as researches in BAM confirm this fact.

The safety margin of 100 °C has been proven over many decades. For use temperatures up to 60 °C, and depending on the intended purpose, BAM only performs oxygen impact tests (test method 1) or flange tests (test method 4).