Brisance of Liquid Explosives

The ability of direct effect or brisant effect from explosive explosion is the brisance of explosives, which is another parameter to measure the blast action of explosives. 

The direct effect of explosive explosion is determined by the pressure of detonation products and action time, also the pressure and momentum to the target. Actions of pressure and momentum are different under various conditions. So the pressure or momentum of detonation products is used to describe brisance. 

The above equation shows that the faster detonation velocity and greater density, the higher brisance. Liquid explosives are noncompressible the density cannot be changed. Their densities and detonation velocities are constants. 

The above equation fully describes that the brisance is linearly proportional to the cubic of explosive density. Increasing the density of an explosive, raises its brisance dramatically. 

The momenrnm aimed on one target is the product of affecting force and affecting time (Eq. 2.49). 

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Modified Saod Test to Determine the Brisance of Liquid Explosives is described in PATR... 

The measuring methods for the brisance of liquid explosives are similar to that of condensed explosives. The measuring difficulty is larger because of the noncompressibility of liquids. The writer/author measured the brisance of liquid explosives using the setup of Fig. 2.26, and summarized a set of methods for evaluating the brisance of liquid explosives. 

As shown in Table 7.29, the brisance and blasting power of liquid explosives seem to increase with the rise of nitric acid concentration. Notably, the explosives prepared with more than 85 % nitric acid concentration can be detonated with no. 8 detonator, whereas the explosives prepared with less than 80 % nitric acid concentration do not possess stable explosion properties instead, they tend to separate into layers after being stored for a short period of time. Moreover, layer separation turned out to be worse for explosives prepared with lower concentration nitric acid. The no. 8 detonator is not able to detonate explosives with separated layers. 

Nitromethane is indeed a liquid explosive of high energy output, however, its poor initiation sensitivity leads to the difficulty in detonation. If mixed with perchloric acid urea, this explosive could be detonated easier with noticeably decreased critical diameter and increased density. All lead to better detonation velocity and brisance. 

Methyl nitrate is a highly volatile liquid, and its brisance is about equal to that of nitroglycerine. Its vapors are both flammable and explosive and produce headaches. Methyl nitrate dissolves nitrocellulose, yielding a gel, from which it rapidly evaporates. 

Organic derivatives of 5-azidotetrazole have been reported by Friedrich [99]. They are more stable and less sensitive than the metallic salts. The methyl and ethyl derivatives are very strong igniting explosives. Ethylene tetrazylazide, that forms an oily liquid, possesses extraordinary brisance and is easily ignited by spark and flames. It easily gelatinizes nitrocellulose [1,99]. Impact sensitivities of 5-azido-l-methyltetrazole and 5-azido-l-picryltetrazole in comparison with the copper salt are summarized in Table 8.19 [79]. 

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