Curve for TNT

The TNT equivalency method also uses an overpressure curve that applies to point source detonations of TNT. Vapor cloud explosions (VCEs) are explosions that occur because of the release of flammable vapor over a large volume and are most commonly deflagrations. In addition, the method is unable to consider the effects of flame speed acceleration resulting from confinement. As a result, the overpressure curve for TNT tends to overpredict the overpressure near the VCE and to underpredict at distances away from the VCE. 

Methods of measuring underwater shock waves by crusher gauges, diaphragm gauges piezoelectric gauges are thoroughly described by Cole (Ref 3) in Chapter 7. Cook (Ref 7) describes the use of a 16- to 64-frame/sec camera to measure the free surface vel produced by a shock wave at the surface, and the determination of the underwater pressure-distance curve for TNT... 

Examples of u vs time curves for TNT and Tetryl, obtained by Jacobs Edwards (Ref 4) are diown in Figs 4—6. As expressed by these authors The determination of a CJ particle velocity and a reaction zone time by the EMV gage has required judgment to select the point on the curves which one would associate with the termination of the reaction. This is not always a simple matter. In our pressed TNT records there was little choice but to take the time at which the u—t curve levels off as the CJ... 

The EPA guideline for evaluation of the far-field (distant) explosion hazards is based on a TNT [TriNitro Toluene] model. Evaluation of the near-field (within the vapor cloud, or near the explosion center) requires departure from the blast-pressure and blast-impulse curves for TNT or modification of the distance/quantity relationship [22]. 

Fig. 3.3. Stress-particle velocity characterizations of many materials have been documented. The explosive cross curves superposed on the materials responses provide approximate loading stress levels to be determined from the intersection of the explosive and material curves. For example, the detonation of TNT produces a pressure of 25 GPa in 2024 aluminum alloy.

In the method which will be presented in Section 6.3.3., the blast parameters of pressure vessel bursts are read from curves of pentolite, a high explosive, for nondimensional distance R above two. For these ranges, using TNT equivalence makes sense. Pentolite has a specific heat of detonation of 5.11 MJ/kg, versus 4.52 MJ/kg for TNT (Baker et al. 1983). The equivalent mass of TNT can be calculated as follows for a ground burst of a pressure vessel ... 

Detonability Curve s for Waxed and Unwaxed Ammonium Perclilorate and for TNT P 451... 

Fig 21 Shock sensitivity curves for waxed and unwaxed ammonium perchlorate and for TNT. Vertical lines at top of graph mark lowest percentage of TMD at which a sub-detonation reaction was observed (Ref 69a)... 

We include a set of Hopkinson-Cranz scaled curves for blast wave properties versus scaled distance, for bare spherical TNT detonated in free air under sea level ambient conditions, as Figure 26. 

Fig. 37 (a) QD-based sensing of cocaine by the formation of a cocaine-aptamer supramolecular structure that triggers FRET and (b) time-dependent luminescence spectra of the system in the presence of cocaine. The inset shows a calibration curve for variable concentrations of cocaine and a fixed so observation time of 15 min. (c) Schematic of the FRET-based TNT sensor and (d) increase of the QD luminescence upon addition of TNT in the competitive assay format. (Reprinted with permission from [220, 221], Copyright 2009 Royal Society of Chemistry and 2005 American Chemical Society)... 

Results of Paterson s work show that the receptor (PETN) is considerably overprimed by the NG based expl, and slightly under-primed by the TNT based expl. The. reflected wave is in each case a rarefaction, very weak with the TNT explosive. The condition for no reflected wave is that the primer C-J point lie on the receptor RH curve. The condition for a stable wave in the receptor is that the receptor CJ point lie on the primer RH curve while the condition for exactly balanced priming is that the two CJ points coincide. The last condition is satisfied at every section in a single expl cartridge Fig 2 shows also, for comparison, the transmitted RH curve for nonreactive waves. The properties of such waves transmitted by the same two primers are summarized by Paterson in the table, but this part is omitted bv Dunkle and by us... 

Dr Price also examined relations between (A) and deton velocity (D). They are presented in Fig 3 for group 1 and in Fig 4 for group 2 Fig 3 shows a representative of group 1, an unconfined cylindrical charge of HBX-1 (RDX/TNT/A1/Wax - 40/38/17/5). Its voidless density is 1.76 g/cc. The curves are for charge diameters d, d, d d which are 6.4, 12.7, 25.4 50.8 mm, respectively. Solid lines are smoothed values from the experimental data which have been extrapolated to A=0.6. The limit line for failure was estimated, as shown on p 694 of Ref 17. A pattern of the same type was previously obtd by Stesik Akimova (Ref 3) for TNT... 

The values a=0.25 and j8 = 0.30, which were chosen originally in 1943 to give agreement with experimental data, then available, proved later to be inadequate. It was found by Cowan Fickett that the value /S = 0.30, used by Kistiakowsky Wilson, proved to be too high to match the observed slopes of D-po curves for RDX/TNT explosives. 

Similar tests were conducted for Tetryl of loading d 1.60 and for TNT of d 1.55. Their luminosity curves for deton in air at atm pressure are given below. The left curves were taken using optical filters with transmission maxima at A=6870A, while the right ones used A= 4510 (Ref 5, Progr-Rept, Apr-June 1949)... 

Dewey (Ref 2) described determination of detonation parameters from photographic observations. Cowan Fickett (Ref 4) determined the effects of the various Kis-tiakowsky-Wilson equation of state parameters on the calculated D - pQ curve for 65/35-RDX/TNT expl mixture. Baum, Stanyukovich Shekhter (Ref 5) presented some parameters of shock waves. Stein... 

The curves logw vs time are given on pp 176-77 for AN, EDNA PETN. This method is not applicable to expls in which.weight loss is the result solely of decomposition and not merely of vaporization or both vaporization and decomposition. It cannot be used for TNT because at the temperatures at which. it. could be applied vaporization and decomposition take place simultaneously... 

Accdg to Andreev 8c Belyaev (Ref 12, pp 201-02), deton vel increases with. diam of chge (if. it is above critical) in the manner of an assymptotic curve which approaches the maximum value. Fig 4.38, p 202 of Ref 12, presents a curve of deton vel vs diameter for RDX of density 1.0 and Fig 4.39 for TNT of density 0.85 in fine and large crysts (not shown here)... 

Belyaev observed (Ref 8, p 293) that for weaker expls, such as mixts contg AN, the relationship betw critical diameter dc and loading density pQ does not resemble that given for TNT in Fig 88 (Our Fig 7). In most of these expls critical diameter increases with. increase of density, as can be seen from Fig 89, p 294 of Ref 8 (Our Fig 12), where curve 1 is for Dinamon (AN 88 8t peat 12%)... 

Figure 3.11 Square-wave voltammograms for TNT solutions of increasing concentration from 1 to lOppm (curves b-k), along with the background voltammogram (curve a) and resulting calibration plot (inset). (Reproduced with permission from Ref. 11.)...

Jefremov and Khaibashev [60] have also investigated melts of TNT with other nitro compounds. They observed deep minima on the isotherms of plastic flow of mixtures of TNT and picric acid, trinitroxylene or 1,8-dinitronaphthalene. corresponding to eutectic mixtures. Unlike those the corresponding curves for mixtures of TNT and 2,4-dinitrotoluene, m- dinitrobenzene, and tetiyl, showed an additive character. 

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