Isothermal Storage Tests

What is the safe storage temperature for shelf life Kinetic data Data from 1 and 2 Isothermal Storage Test... 

Isothermal storage tests (1ST), scanning or isothermal heat-flux micro-calorimeters, thermal activity monitor (TAM)—see Section 2.3.2.1,... 

In the isothermal storage test (1ST) [115, 116], the heat generated at constant temperature by reacting or decomposing substances is measured as a function of time. An example of an 1ST is shown in Figure 2.17. The test is... 

FIGURE 2.17. Cross-Section of an Isothermal Storage Test (1ST). 

Figure 6, The induction period, of the aiitocatalytic reaction, of 2 cm of a high explosive of the tiue AC type confined in the closed cell and subjected to the isothermal storage test performed at a T, on the low temperature side, recorded for the time, At, from the insertion of the cell into the isothennal storage testing device till the start of the autocaialylic reaction of the high explosive at the T,.

Based on our understanding above referred to, an important and useful proposition is obtained that it is possible, in principle, to regard the SADT calculated in accordance with Eq. (59) holding for the induction period of the autocatalytic reaction, or of the quasi-autocatalytic reaction, of 2 cm of a chemical of the AC type, including every powdery chemical of the quasi-AC type, confined in the closed cell and subjected to the isothermal storage test, as the SADT for the chemical, having an arbitrary shape and an arbitrary size, confined in an arbitrary closed container of the corresponding shape and size, and placed in the atmosphere under isothermal conditions. 

When confined in the closed cell and subjected to the isothermal storage test performed at a T 2 cm of a powdery chemical of the quasi-AC type warms slowly up to the T, but the temperature remains near the T, over a long time, because a phase transition, the endothermic melting, of the chemical occurs almost simultaneously with the exothermic decomposition reaction all through this time. Once, however, the chemical finishes melting in the course of time, an apparently sudden quasi-autocatalytic reaction of the resultant liquefied chemical starts. 

It is always indispensable for almost all self-heating chemicals, irrespective of whether they are of the TD type or of the AC type, to determine the or the T, of each run by inserting the reference cell assembly into the adiabatic jacket in the adiabatic self-heating process recorder, or into the aluminium block bath in the isothermal storage testing device, prior to the insertion of the sample cell... 

Figure 31. 2.2 g of silica powder, the volume of which is about 2 cm, is charged in a closed cell, i.e., the cell with which the reference cell is prepared. In this photograph, however, the cell is filled with milk in place of silica powder for the convenience of photography. It has been made a rule in the adiabatic scIf-heating test performed for every chemical, irrespective of liquid and powdery, of the TD type to use silica powder as the reference material. In this connection, silica powder is used as the reference material in the isothermal storage test as well. 

That is, it is clear that a part of the heat of the exothermic decomposition reaction of BPO charged in each of the two kinds of metallic open-cup cells is used to heat up the cell as well as BPO itself. In other words, it follows that it is most advisable to use the glass cell having a small heat capacity in every thermal instability testing apparatus including the isothermal storage testing device. 

This testing condition shows clearly that the BAM test is a sort of isothermal storage test, i.e., a sort of non-adiabatic self-heating test, performed for 400 cm of a chemical of the TD type placed in the atmosphere under isothermal conditions. The BAM test thus provides a value of T for 400 cm of a chemical, of the TD type, placed in the atmosphere under the specified isothermal conditions of the BAM test. 

The values of for several similar bodies of a gas-permeable oxidatively-heating substance, having each a definite shape and a relatively small value of r, placed each in the atmosphere under isothermal conditions, are determined actually by performing a series of isothermal storage tests, respectively. 

It is manifest that the above procedure is not a calculation method to the effect that the for a heap of a gas-permeable oxidatively-heating substance, having a definite shape and an arbitrary value of r, placed in the atmosphere under isothermal conditions, is calculated by substituting various physical and chemical quantities concerned into an equation, but an extrapolation method to the effect that the for the heap is determined by extrapolation on the graph in accordance with an empirical formula, In [(cfc Tc )/t ] = - alT + b, which is determined by performing actually a series of isothermal storage tests for several small-scale similar bodies of the substance, respectively. 

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