Open-cup cell

Figure 1. The whole self-heating process up to the thennal explosion of2 em of a chemical of the Tl) type charged in the open-cup cell, or confined in the closed cell, in accordance with the self-heating property of the chemical, and subjected to the adiabatic self-heating test started from a Tj.

It will, thus, be necessary here for us to confirm a posteriori, with reference to some concrete example, the validity of the linear approximation of the selfheating process or curve, in the early stages, of 2 cm of a chemical of the TD type charged in the open-cup cell, or confined in the closed cell, in accordance with the self-heating property of the chemical, and subjected to the adiabatic self-heating test started from a 7. The confirmation illustrated below is performed with reference to the experimental data which are determined for the ten organic liquid peroxides and are listed in Table 8 in Subsection 5.7.1. 

Secondly, let us assume the mean value of T, to be 60 °C in the adiabatic selfheating tests performed each for the ten organic liquid peroxides charged each in the open-cup cell, because the value of T,. ranges from 26 °C for 69.5 % tert-hexyl peroxyneodecanoate in isoparaffin (THPN) to 100 °C for 99 % d -tert-butyl peroxide (DTBP), as stated in Subsection 5.4.1,... 

The linearity, of this order, of the self-heating process or curve, of 2 cm of a chemical of the TD type subjected to the adiabatic self-heating test started from a Ts, recorded for the time, A t, required for the temperature of the chemical to increase by the definite value of AT of. 25 K from the r is exemplified by a digital record of the self-heating process, which is presented in Table 5 in Section 4.7, of 2 cm of 99 % tert-butyl peroxybenzoate (TBPB) charged in the open-cup cell and subjected to the adiabatic self-heating test started from a nominal T, of 76 °C, for the time, At, required for the temperature of TBPB to increase by the definite value of AT of. 25 K from the nominal T. ... 

Individual TG-DTA curves, which are each recorded with a glass open-cup cell, 5 mm in diameter, 2,5 mm in depth, at a value of Zf of 2,5 IGmin in air at... 

On the other hand, individual TG-DTA cuiwcs, which are also each recorded with the glass open-cup cell, 5 mm in diameter, 2.5 mm in depth, at the same value of 0 of 2.5 K/min in air at atmospheric pressure, of four of the live powdery chemicals of the quasi-AC type, which are listed in Table 26 in Subsection 10.4.1, are presented in Fig. 9. 

Three kinds of Pyrex glass open cells, i.e., the open-cup cell, the draft cell and the touch-flow cell, as well as one kind of Pyrex glass closed cell, which each have a capacity of about 2 cm are available for the adiabatic self-heating process recorder. The three kinds of glass open cells are shown in Fig. 19. 

As a matter of fact, however, the experimental procedure explained in the present section is, in principle, in common with (1) the procedure for 2 cm of a non-volatile liquid or powdery chemical of the TD type charged in the open-cup cell, which is explained in Section 5.4, and (2) the procedure for 2 cm of a gas-permeable oxidatively-heating substance charged in the draft cell, which is explained in Section 7.4 and in Subsection 8.4.1, as well as (3) the procedure... 

The self-heating processes of 2 cm each of three samples of BPO charged each in the three kinds of open-cup cells and subjected each to the adiabatic self-heating test started from each near 82 °C were recorded. 

It has been ascertained, in result, that the rate of increase in temperature of BPO charged in the stainless steel open-cup cell and that of BPO charged in the aluminium open-cup cell are both much less than that of BPO charged in the glass open-cup cell, keeping the other conditions constant (Fig. 41). 

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. 

The self-healing process, of 2 cm of BPO charged in the glass open-cup cell and subjected to the adiabatic self-healing test started from a near 82 IC, recorded in temperature increments of 3 K from the f. 

The glass open-cup cell, into which the thermocouple, which is covered with a glass capillary tube, to measure the temperature of BPO is inserted. 

For the above reasons, it is not advisable to use the closed cell in the adiabatic self-heating test from a point of view that we should always endeavor to get a on the low temperature side, or on the safety side, for every chemical of the TD type. We have, nevertheless, no choice but to use some closed cell in the adiabatic self-heating test performed for a chemical of the TD type which is volatile or decomposes to evolve corrosive and/or toxic gases while tested. Conversely speaking, it follows that it is always advisable to use the thermally sensitive glass open-cup cell in the adiabatic self-heating test, unless the chemical tested is volatile or decomposes to evolve corrosive and/or toxic gases while tested. 

In the case of the digital record of the self-heating process exemplified in Table 5, the digital D.C. microvoltmeter indicates that the exact value of the T, of this run is 3111.5 jUV. This value of T, is determined, based on the fact that the indication of the digital D.C. microvoltmeter has fluctuated constantly between 3111 and 3112 juV for 1 to 2 h after the thermal equilibrium state has been attained around the reference material charged in the open-cup cell and inserted into the adiabatic jacket maintained at the nominal T, of 76 °C in the adiabatic self-heating process recorder. 

Now, one temperature value, of 2 em of TBPB charged in the open-cup cell, of 3158 ttV was indicated by the digital D.C. microvoltmeter 37 min after the start of the adiabatic self-heating test for TBPB, and the other temperature value, of 2 cm of TBPB in the cell, of 3168 iN was indicated by the micro voltmeter 45 min after, so that the time. At, required for the temperature of 2 cm of TBPB in the cell to increase by the definite value of T of 1.25 K from the must exist between 37 and 45 min. 

This time, At, is calculated at 41.2248 min by the proportional allotment. This proportional allotment may be allowable, because an almost constant rate of increase in temperature of 2 cm of TBPB charged in the open-cup cell and subjected to the adiabatic self-heating test has been realized all through this run. A value of Inzl t of 3.71904 is, hence, calculated immediately. 

The result of the regression analysis applied, in order to calculate the heat generation data of TBPB, to five combinations of the value of In t with that of 1/T, which are each determined, based on five digital records obtained each from five adiabatic selfheating tests, which are started from each T,. in the range of 73.18 to 79.62 °C with mutual intervals of 1 2 K, performed each, for 2 cm each of five samples of TBPB charged each in the open-cup cell, for the time, A t, required for the temperature of each sample of TBPB to increase by the definite value of AT of 1.25 K from the corresponding T,. Data used are in common with those presented in Fig. 45 and plotted in Fig. 46. 

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