Correlation between self-ignition of a dust layer on a hot surface and in baskets in an oven.

Evaluation of self-ignition hazard of bulk materials requires experimental determination of self-ignition temperatures as a function of volume. There are two standardised methods: (1) determination of the self-ignition temperature of dust samples in oven and (2) measurement of the self-ignition temperature of a dust layer deposited on a hot surface. Sometimes, the sample behaviour during these tests makes the second method difficult to apply.

MIKE 3 versus HARTMANN apparatus: comparison of measured minimum ignition energy (MIE).

In this study, MIE values measured with two different explosion tubes, HARTMANN and MIKE 3, are compared. Generally, MIKE 3 apparatus provides MIE results, which are equal or lower to those measured with the HARTMANN apparatus; this is particularly true for the energy ranges between 1 and 10mJ and higher than 100mJ. Differences observed can modify samples classification according to their sensitivity to electrostatic ignition sources.