Explosive Strength

TNT Equivalence. Explosion strength is often expressed as equivalent mass of TNT in order to permit estimates of possible explosion damage. For BLEVEs and pressure vessel bursts, using this equivalence is unnecessary because the methods mentioned above give explosion blast parameters which relate directly to the amount of possible damage potential. However, the concept of TNT equivalence is still useful because it appeals to those who seldom deal with blast parameters. For reasons explained in Section 4.3.1, BLEVEs or pressure vessel bursts catuiot readily be compared to explosions of TNT (or other high explosives). Only the main points are repeated here. 

Calculation of blast overpressure parameters There are three major methods in use today. One is the TNT Equivalency Methbd which gives inaccurate results for vapor cloud explosions. The other two methods are the Strehlow Curves from Baker 1983 and the Multi-Energy Method from TNO 1985. Both provide a family of curves based on flame speed or explosion strength. These curves are used to select dimensionless parameters which are then unsealed to determine the actual overpressures. 

Molecules such as TATP (49) possess explosive strength similar to TNT. Furthermore, TATP is extremely sensitive to heat and vibrational shock and can be ignited with an open flame or small electrical discharge i.e. does not need a primer unlike conventional explosives. 

It is customary to rate explosive strength on a relative basis, ie, as a percentage of the strength of some standard explosive - usually TNT or some standard Dynamite. This rating is based on comparison tests, the most common of which is the Ballistic Mortar Test (See Vol 2, p B6-R)... 

Explosion Strength or Power. As regards energy content and high deton velocity, NGc occupies first place by the customary methods... 

Physiological Properties. See under Toxicity Power. See under Explosive Strength Pressure Developed on Explosion of One Kilogram in One Liter— I2498kg/cm2 for NGc vs 12048 for NG (Ref 6, p 298 Ref 19, p 132) Reaction on Explosion, See Decomposition (or Explosion) Equation... 

As regards explosive strength, nitramines occupy a position midway between nitro compounds and nitric esters. They also hold a central position regarding other properties, such as chemical stability and sensitiveness to impact and friction. 

As an explosive the substance is very powerful. Its expansion in the lead block is about 500 cm3, j.e. its explosive strength is midway between that of tetryl and penthrite. At a density of 1.54 it detonates at a rate of 7500 m/sec. 

Power by Trauzl Test — Naoum (Ref 15, p227) gives 590cc for I0g sample TNT produces expansion ca 300cc Rifle Bullet Impact Test — 100% explosions Strength — See Power... 

Class IV. Nongelatinous (powdery) Nitro-gIycerin-Ammonium Nitrate Explosives, known as Ammonium Nitrate Dynamites or Ammonia Dynamites. They contain sub stantial amounts of AN which usually replaces part of NG and of Na nitrate. The replacement of part of Na nitrate by AN increases the volume of gas produced on detonation. They have approximately the same explosive-strength values as do the Gelatin Dynamites, but have lower rate of detonation and brisance values (Ref 62, p640)... 

In addition to measuring shock wave and bubble energies, underwater tests also can measure the shock wave impulse, another indicator of explosive strength. The shock wave impulse is derived by measuring the area under the pressure-time curve for a selected integration time interval at a known distance from the explosion... 

The explosive strength of dinitrochlorohydrin is assumed to be about 80% that of nitroglycerine. As a component of mining explosives chlorohydrin dinitrate has the disadvantage of producing hydrogen chloride on explosion. It does not seem to be any more of practical use. 

The substance is characterized by excellent chemical stability. Its explosive strength, as measured by the expansion produced in the lead block, is equivalent to about 75% of the explosive strength of nitroglycerine. 

Butane-1,2,4-triol trinitrate, also called nitrobutanetriol , is a good solvent of collodion cotton. It is less volatile than nitroglycerine and a chemically stable compound. Its explosive strength is not much inferior to that of nitroglycerine. Its heat of explosion is 1440 kcal/kg [1],... 

This is a crystalline substance of great explosive strength, possessing a low sensitiveness to shock. 

It was first obtained by Hertz [67] who proposed its use as an explosive, since (in the authors opinion) it develops greater explosive strength that PETN but is less sensitive. Tollens and Apel [68] have prepared the initial alcohol (m.p. 156°C) resulting from the reaction of acetone with formaldehyde in the presence of calcium hydroxide, to which they attributed the structure of an enneaheptitol anhydride without, however, determining which hydroxyl groups were dehydrated. 

Both esters, and specially hexanitroinositol, were suggested by Crater [71] for use in explosives practice instead of tetryl for filling detonators and boosters. In explosive strength, sensitiveness to mechanical shock, and stability both esters are similar to nitromannite. References to quebrachitol pentanitrate can be found in the patents of Burke and McGill [72]. 

Trinitrophenoxyethv 1 -co-nitrate is more sensitive to impact than picric acid and less so than tetryl. Its explosive strength approaches that of tetryl, since it produces an expansion in the lead block of 350-355 cm3. 

Methylamine nitrate was obtained by treating methylamine with concentrated nitric acid (66%). The explosive strength of methylamine nitrate exceeds that of TNT. Its hygroscopidty, which is even higher than that of ammonium nitrate, is a disadvantage. 

Methylamine perchlorate, CH3NH3C104 (m.p. 210°C) [28], is a substance that resembles cyclonite and PETN in explosive strength. However, it is more sensitive to impact than these compounds. 

As for its explosive strength, guanidine perchlorate is similar to tetryl. Its sensitiveness to shock is comparable with that of picric acid. The rate of detonation is 6000 m/sec at a density of 1.15 and the net expansion in the lead block test is about 400 cm3. 

T. Urbanski and Kowalski [34] examined the properties of those perchlorates as well as a range of others, not previously described, to determine their sensitiveness, stability, and explosive strength (Table 115). 

T. Urbanski and Kowalski [34] have studied the explosive properties of pyridine perchlorate as well as quinoline and its nitro derivative perchlorates. Due to the introduction of a nitro group the sensitiveness to shock of the quinoline perchlorate increased, but to a smaller extent than the authors had previously observed with primary aromatic amines. The introduced nitro group markedly favoured the increase of explosive strength of the perchlorates (Table 116). 

The explosion strength of the product is low, but its sensitivity relatively high. 

Since such a high explosive strength is rarely required, blasting gelatin is scarcely ever used in practice. 

Since this regulation is still recent, the values given in the following table, as well as the values given under the appropriate headings of the individual explosive materials, are still based on the older method, in which a 10-g sample is employed. Other conventional methods for the determination of the explosive strength are the ballistic mortar test and the sand test. 

The compound is less volatile than nitroglycerine, practically insoluble in water and petroleum ether, soluble in alcohol, acetone, ether, benzene, and chloroform, and is a good gelatinizer of guncotton. Its explosive strength is close to that of nitroglycerine. 

Properties Yellow to red crystals or granules. Does not melt on heating but explodes when heated to 300°. It must be loaded in projectiles by pressing or tamping. Ammonium picrate absorbs moisture and in wet condition reacts slowly with metals, particularly copper and lead, to form picrates which are sensitive and dangerous. Its explosive strength is inferior to that of TNT, but it is very valuable because of its extreme resistance to impact, shock, and friction. It is not detonated by fulminate. Commonly used with a booster of picric acid or Tetryl. Rate of detonation 6500 m/sec. (d = 1.45). 

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