Impact, sensitivity

For the impact sensitivity determination, several types of impact testing apparatus, known also as Fallhammer Apparatus, are used US Bureau of Explosive Impact paratus (BoE), US Bureau of Mines Impact Apparatus (BoM), Picatirmy Impact. paratus (PA), German Bundesanstdt fur Materialpriifung. paratus (BAM), and others (Baum et al., 1959, 1975 Impact Sensitivity Test, 1962 Kamlet and Adolph, 1979 Koenen et al., 1961 Kohler and Meyer, 1993 McIntyre, 1980 Safety and Performance Tests, 1972 Sensibilite auchoc, 1987 Wollert-Johansen, 1978). 

All these apparatuses operate on the same principle a sample of the tested explosive is subjected to the action of a drop weight. The parameter to be determined is the mass of the drop weight and the drop height at which the initiation of the sample may occur. The main difference between the apparatuses 

The BAM Impact Apparatus, which seems to give reasonably reproducible results, is described below. 

A sample placed between two flat, parallel, hardened steel surfaces is subjected to the drop weight impact. Depending on the characteristics of the tested explosive, the drop weight mass, and the drop height (i.e., impact energy), the initiation of the sample may or may not occur. The drop height that enables the initiation of the tested explosive is the measure of its impact sensitivity. 

Pressing the locking and unlocking device lever arm, the drop weight is unlocked, consequently impacting the upper roller of the piston device. The sample response is observed. 

An excellent summary of a large number of impact and friction tests of LA and to a lesser extent of some other common explosives has been published by Avrami 

Despite the above-mentioned problems, most common primary explosives have been compared and the order of their impact sensitivity has been evaluated by various authors. The sensitivity of LA and SA is lower than that of MF and comparable to that of PETN. The sensitivity of DDNP is mentioned as lower than for MF [4, 18, 50]. 1-Amino-l-(tetrazol-5-yldiazenyl)guanidin (GNGT, tetrazene) is sometimes reported as slightly more sensitive than MF [41] but slightly less sensitive than MF by [33], SF, often mentioned as a very sensitive substance, has an impact sensitivity comparable to that of LA. Its high sensitivity to friction is sometimes misleadingly attributed to impact. TATP is often reported as extremely sensitive but, as indicated by the figures in Fig. 2.15, the results are relatively evenly spread from about 0.2 to over 3 J. Of the usual primary explosives, LS shows the lowest sensitivity to impact. 

Impact sensitivity significantly depends on many aspects. Let us look at some of these properties starting with crystal size of the material under test. Colloidal silver azide prepared from concentrated solutions exhibits significantly lower sensitivity (0.5 kg from 77.7 cm) than coarser crystals prepared from diluted solutions, which required less than half the energy (0.5 kg fi om 28.5 cm). MF measured under the same conditions for comparison required 12.7 cm with the 0.5 kg hammer [20]. It is interesting to note that the impact sensitivity of S A (in fine powdery form), which is considered very sensitive, is lower than that of MF. Similar investigations have 

A good comparison of impact sensitivity for various explosives is presented in Fig. 2.18. It shows probability of initiation at specific drop heights expressed as a number of positive trials out of 5. 

Impact sensitivity is further influenced to a very large extent by the thickness of the layer of explosive tested. The sensitivity of the azides of silver, lead, and mercury increases with the layer thickness, that of cadmium is almost constant. 

Titanium/PTFE/Viton and Zirconium/PTFE/Viton 

Pyrolants from micro-metric Ti (22 gm) and Zr (10 gm) and 5 gm PTEE with 12 wt% Viton are less sensitive to impact than MTV. TiTV with 40 wt% Ti is nearly impact insensitive with an impact energy of 47 J. However, at higher metal content, TiTV shows impact energies of 13 J (60wt%) and 14) (80wt%) respectively. ZrTV shows similar impact energies 13 J (60 wt% Zr) and 11J (80wt% Zr) [9]. 

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Chlorine heptoxide is more stable than either chlorine monoxide or chlorine dioxide however, the CX C) detonates when heated or subjected to shock. It melts at —91.5°C, bods at 80°C, has a molecular weight of 182.914, a heat of vapori2ation of 34.7 kj/mol (8.29 kcal/mol), and, at 0°C, a vapor pressure of 3.2 kPa (23.7 mm Hg) and a density of 1.86 g/mL (14,15). The infrared spectmm is consistent with the stmcture O CIOCIO (16). Cl O decomposes to chlorine and oxygen at low (0.2—10.7 kPa (1.5—80 mm Hg)) pressures and in a temperature range of 100—120°C (17). It is soluble in ben2ene, slowly attacking the solvent with water to form perchloric acid it also reacts with iodine to form iodine pentoxide and explodes on contact with a flame or by percussion. Reaction with olefins yields the impact-sensitive alkyl perchlorates (18). 

Milling of impact-sensitive materials should generally be avoided. 

Impact sensitivity can be gauged by striking a few crystals of the compound on a metal last with the ball of a ball-pein hammer. Ignition, smoking, cracking or other sign of decomposition are considered hazardous. 

Mannitane Tetranitrate. C6H80(0N02)4, mw 344.16, N 16.28%, OB toC02 -13.9% yellowish brown syrupy liq msoi in w, sol in ale eth. Can be prepd by gradual dissolution of lp of mannitane in a cooled mixt of 5ps coned nitric acid and lOps coned sulfuric acid. The slurry is then poured into a large quant of ice w, and the prod sepd by filtn, washed dried. It is a powerful expl with the same impact sensitivity asNG... 

Impact sensitivity. PA app 10—11 inches (18.3mg sample) vs 8 for RDX, hydrazine salt 15 inches (1 lmg sample) BM app 14— 2lcm vs 70—100+ for RDX and 100+ for TNT, hydrazine salt 92cm (Ref 13), also in this Ref are listed the impact sensy of 8 samples of MEDINA coated with wax (15—31cm)... 

N.D. Mason, Impact Sensitivity Determinations of Explosive Compounds Tested During the Period 1 Jan to 1 Nov 1950 , NOL NAVORD Rept 1589 (Nov 1950) 10) A.H. Lamberton,... 

Melamine has been used as a flash reducing agent in propints (Ref 10). It is nonhygr, of low volaty, highly resistant to hydrolysis up to 60°, and is practically neutral in aq solns (pH 7.7). Tests conducted at PicArsn indicated satisfactory impact sensitivity (40 inches with 2kg wt), and no sand crushed in the Sand Test bomb... 

N 16.47%, OB to C02 —103.4%, triclinic needles (from ale). prisms (from acet), mp 238.2°, bp expl at 415°, d 1.48g/cc. Insol in w, si sol in hot ale eth, misc in hot acet benz. Can be prepd by treating mesitylene with a mixt of. nitric sulfuric acids in the cold (Refs 2 3). Blanksma (Ref 4) prepd it by dissolving mesitylene in sulfuric acid, partial sulfonation taking place, and then adding the soln to nitric acid, with the pptn of trinitio-mesitylene. Kholevo (Ref 6) nitrated mesitylene with nitric acid 27, sulfuric acid 69, water 4% to yield white crysts. The expl power of trinitro-mesitylene is less than PA (Ref 9), and it develops a bomb press 84% that of TNT (Ref 8), Its impact sensitivity is 52% that of TNT (Ref 7), and it expls at 415° (Ref 5)... 

TNMe on alkaline hydrolysis. In an ion exclusion-partition chromatographic method for the sepn of acids, TNMe emerged from the column betw citric and itaconic acids (Ref 36) Impact Sensitivity. On the BRL machine (1kg wt), using a noisemeter to detect explns, the 50% expin height was found to be 218cm. A 50/50 mixt with kerosene had a 50% expln height of 130cm (Ref 21)... 

N 22.08%, OB to C02 -52.96%, cryst, mp 96-97° (Ref 3). Prepd from 2,3,4,6-tetra-nitrophenylmethylnitramine and m-nitrotetryl upon heating with methyl alcohol (Refs 1 2). The expln temp (187°) was obtd on heating the sample at the rate of 5°/min, while a temp of 198° was detn by heating at the rate of 20°/ min (Refs 2 3). Impact sensitivity with the Kast app, max fall for no detonation using a 10kg wt (6 shots) was 15-16cm vs 14cm for... 

CH2(0CH20N02)2, mw 198.11, N 14.14%, OB to C02 —8.08%, liq. Prepn from formaldehyde or trioxymethylene with mixed acid. Impact sensitivity FI is 6% of PA. Power by lead block test is 148% of PA, and the material is described as not very powerful . Chemically unstable and reactive with moisture Refs 1) Beil — not found 2) Blatt, OSRD 2014(1944)... 

Its impact sensitivity was comparable to RDX, and the Trauzl Pb block expansion was found to be 130 (PA 100). The rates of deton of 30mm diameter charges in cardboard tubes were 5630m/sec at d 1.10g/cc,6970m/sec at 1.50g/cc, 7560m/sec at 1.60g/cc, and 7830m/sec at 1.65 g/cc. Medard concluded that Methylglucoside... 

Impact Sensitiveness, by Kast apparatus with 2kg wt, it explodes at 40cm drop, vs 4cm for NG. Even when mixed with kiesetguhr it is less sensitive than NG (Compare with FI) Initiation Sensitiveness. See Sensitiveness to Initiation... 

Nitroisobutylglycol dinitrate). CH3.C.N02(CH20N02)2, mw 225.14, N 18.67%, OB to C02 —24.87%, mp 38°, ignites above 240°. Prepd from the glycol by nitration with mixed acid, with 90% yield. Brisance, crushes 53g sand, equivalent to Tetryl. Qc is 531.4cal/mole. Impact sensitivity, FI 86% relative to PA, with Bruceton No 5 machine,... 

Impact Sensitivity. > 100cm with 2kg weight or less sensitive than TNT Thermal Stability. Unsatisfactory (about 6 minutes in the 82.2° Heat Test)... 

The resulting compound was an expl, very volatile and very unstable (2 minutes in the 82.2° Abel test, compared with 10—15 minutes for NG). The impact sensitivity (BurMines, 2kg weight) was 100cm+. Because of its poor stability, it was not recommended for use as a military expl... 

Explosion Temperature, Ignited above 240° Heat of Combustion. Q 531,4kcal/mole Impact Sensitivity 11cm with BurMines app with 2kg wt (less sensitive than NG)... 

N 20.29%, OB to C02 -65.65%, white prisms, mp 190°, explodes. Readily sol in organic solvents. Prepn by gently refluxing bis-tri-methylethylenenitrosochloride with coned nitric acid (d 1.42g/cc) (Refs 1 3). 700.46kcal/mole (Ref 4). Impact sensitivity is less than TNT (Ref 2). Power by ballistic mortar is 106% of, TNT (Ref 2)... 

H. Jackson, Impact Sensitivity of Lead Azide in Various Solid and Liquid Media ,... 

Impact sensitivity. NOL machine with a 2.5kg wt on sandpaper gives 99cm for 50% positives (Tetryl 32cm) (Ref 23, p 3) -... 

Impact sensitivity of ground propellant, 50% point with 2-kg hammer, cm 8 170... 

Expl temp is 320°, flaming deton occurs. Impact sensitivity is 1 cm using a 20g weight on a g equiv wt of compd. Expln occurs on contact with either dil hydrochloric or nitric acids or coned sulfuric acid Refs 1) Gmelin, Syst Nr 11 (1940), 311 2) Sax (1968), 1137... 

Brisance. By Kast app ( Stauchprobe ) using a 10.5mm high Cu cylinder 4.5mm compression vs 5,1mm for NG and 4.0mm for PA Impact Sensitivity. As detd in a special app designed for liq expls less sensitive than NG and more sensitive than PA Trattzl Pb Block Expansion. 435cc with lOg sample vs 493cc for NG and 305cc for PA... 

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