1   Testing of materials for ignition sensitivity to gaseous oxygen impacts

For testing, solid materials are divided and liquids are applied onto ceramic fibers. A sample mass of ca. 0.1 g to 0.5 g is placed into a heatable sample tube of 15 cm3 in volume.
The sample tube is connected by a pipe and a pneumatically operated quick opening valve to a high-pressure oxygen accumulator. After the pipe and sample tube are at initial pressure pa (generally ambient pressure) and the sample has reached the test temperature, the quick opening valve is opened and preheated oxygen (generally 60 °C) of final pressure pe flows abruptly into the pipe and sample tube.
In this way, the oxygen in the sample tube is almost adiabatically compressed from initial pressure pa to final pressure pe and heated. A possible reaction of the sample with oxygen is indicated by a steep temperature rise in the sample tube.
Assessment criterion:
If there is a reaction, further test series are performed at a lower pressure ratio pe/pa until the compression ratio is found, where no reaction of the sample with oxygen can be detected in a series of five consecutive gaseous impacts. If this result is confirmed in a second test series of five consecutive oxygen impacts, the tests can be finished or continued at a different test temperature.