Comparative analysis of the methods for SADT determination

Abstract

The self-accelerating decomposition temperature (SADT) is an important parameter that characterizes thermal safety at transport of self-reactive substances. A great many articles were published focusing on various methodological aspects of SADT determination. Nevertheless there remain several serious problems that require further analysis and solution. Some of them are considered in the paper. Firstly four methods suggested by the United Nations “Recommendations on the Transport of Dangerous Goods” (TDG) are surveyed in order to reveal their features and limitations. The inconsistency between two definitions of SADT is discussed afterwards. One definition is the basis for the US SADT test and the heat accumulation storage test (Dewar test), another one is used when the Adiabatic storage test or the Isothermal storage test are applied. It is shown that this inconsistency may result in getting different and, in some cases, unsafe estimates of SADT. Then the applicability of the Dewar test for determination of SADT for solids is considered. It is shown that this test can be restrictedly applied for solids provided that the appropriate scale-up procedure is available. The advanced method based on the theory of regular cooling mode is proposed, which ensures more reliable results of the Dewar test application. The last part of the paper demonstrates how the kinetics-based simulation method helps in evaluation of SADT in those complex but practical cases (in particular, stack of packagings) when neither of the methods recommended by TDG can be used.