PETN used for percussion caps

At all events, however, it will be reasonable, in practice, to consider a temperature 30 K lower than the value of SADT calculated herein for a high explosive of the true AC type, 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, as the upper limit temperature for the safe handling of the high explosive. For instance, 25 °C will be the upper limit temperature for the safe handling of nitroglycerin, 45 °C for nitrocellulose, but 35 °C for nitrocellulose contaminated by metals, 80 °C for PETN used for percussion caps, and so forth. 

When confined in the closed cell and subjected to the isothermal storage test performed at a T, on the high temperature side, say, in the range of 125 to the melting point of PETN, i.e., 130 °C, 1.8 g of PETN used for percussion caps, the volume of which is about 2 cm behaves certainly like a powdery chemical of the quasi-AC type in such a manner as to start the quasi-autocatalytic reaction simultaneously with the finish of its melting a very short time after the start of the isothermal storage test in accordance with Eq. (59). This manner is the same as that shown in Fig. 7 presented in Section 3.3. 

Results of elemental analysis for PETN used for percussion caps tested herein are as follows ... 

When confined in the closed cell and subjected to the isothermal storage test performed at a T, of 120.9 °C, 1.8 g of PETN used for percussion caps started the autocatalytic reaction about 12.4 h after the start of the isothermal storage test. 

Comparison of the plot of nAt versus T, made for 1.2 g each of five samples of PETN used for medicine with the plot made for 1.8 g each of eleven samples of PETN used for percussion caps is presented in Fig. 134. 

The SADT for PETN used for percussion caps is thus calculated, in accordance with the definition of the SADT, at 109.670 °C as a value of T, corresponding to a value of At oi 10,080 min in the empirical formula, nAt = 34593.34/r, - 81.1463, i.e., Eq. (59) holding for the induction period of the autocatalytic reaction of 1.8 g of PETN, used for percussion caps, confined in the closed cell and subjected to the isothermal storage test. 

It is, however, inferred that, as a matter of fact, PETN used for percussion caps will not start the exothermic decomposition reaction at temperatures below 115°C. ... 

PETN used for medicine is prepared by recrystallization from acetone solution of PETN used for percussion caps. 

As seen in Fig. 134, the time. At, required for PETN used for medicine to start the autocatalytic reaction is much longer than that required for PETN used for percussion caps to do so. This may be regarded as an effect of the elimination, by recrystallization, of impurities contained in PETN used for percussion caps. 

Figure 134. Comparison of the plot of ln.df versus /T, made with five combinations of the value of nAl with that of 1/T, which are each determined for five induction periods, of the autocatalytic reaction, of 1.2 g each of five samples of PETN used for medicine, confined each in the closed cell and subjected each to the isothermal storage test performed at each T, in the range of 115.1 to 120.9 "C with mutual intervals of 0.2 2 K, recorded each for the time, A /, from the insertion of each cell into the isothermal storage testing device till the start of the autocatalytic reaction of PETN used for medicine at the corresponding T, with, the plot made for 1.8 g each of eleven samples of PETN used for percussion caps, placed each under the same conditions as the former.

The purity of PETN in that used for percussion caps is 98.9 % on the basis of the percentage of nitrogen. 

According to Friederich s patents the organic tetrazylazides are more stable and less sensitive than the salts. He suggested that they be used, either alone or in various mixts, as ignition compns for percussion caps, detonators, electric primers, detonating fuses, etc. Suitable secondary charges are PETN, RDX, Tetryl or TNT Refs 1) Beil 25, 347, (HO) [1971... 

Compatibility with metals. Moderately moist material does not attack metals it resembles Pb Styphnate in this respect Compatibility with explosives. Mixts with equal parts of TNT, PA, RDX, PETN, Tetryl, AN and Sb sulfide, stored for 40 days in a dry atm at 50°, remained unchanged Uses. Pb trinitrophloroglucinol has been proposed as an ingredient of priming compns, and for use in percussion caps and detonator formulations (Refs 2,3,4,5,7 9)... 

Tetryl (C7H5N508) is a pale yellow crystalline solid. It is moderately sensitive to initiation by friction and percussion and is used in the form of pressed pellets as primers for explosive compositions that are less sensitive to initiation. It is slightly more sensitive than picric acid and considerably more sensitive than TNT. In the early 1900s, tetryl was used as base charges for blasting caps but now has been replaced by PETN and RDX. During World War II, tetryl was used as a component of explosive mixtures. 

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