2025 Volume 18 Issue 1 Pages 15-21
The hazards of self-heating substances are generally measured under a constant airflow rate or natural convection. However, chemical materials are used under a wide range of airflow conditions. An increase of airflow rate around a chemical material is indicative of an increase in the supply of reactants, such as oxygen gas, which increases the risk of self-ignition. However, an excessive air supply may exhibit a cooling effect and reduce the risk of self-ignition. The underestimation or overestimation of these hazards can occur when the effects of the airflow rate are not fully considered.
In this study, the effect of airflow on the self-ignition temperature was assessed using isothermal Grewer oven test and activated carbon as the model material. The tests showed that the self-ignition temperature of activated carbon decreased owing to an increase in the oxygen supply with an increase in the airflow rate, while a significant increase in the airflow rate resulted in an increase of self-ignition temperature owing to cooling with air. These results indicate that the isothermal Grewer oven test under a variable gas flow rate can be used to estimate the risk of underestimating or overestimating hazards owing to gas flow.
