Explosions in Water

One of the easiest and best methods of evaluting the low pressure end of the detonation product isentrope of an explosive is to study its effect under water. Although military laboratories throughout the world have been studying the effects of explosives under water for many decades, the problem of what type of an explosive is best for particular underwater applications is still being debated. 

A good method of testing an equation of state for detonation products and the numerical method of describing the explosive burn is to compare the calculated behavior of an explosive bubble under water with that observed experimentally. 

The BKW equation of state constants used for the explosives and the HOM equation of state are given in Table 5.1. The equation of state for water was Ug = 0.1483 -I- 2.0Up, 7s = 1.0, C, = 1.0, and a = 0.0001. The method of burning the explosive was the C-J burn technique found adequate for diverging detonations in Chapter 2. 

The SIN code described in Appendix A was used to study the flow resulting from detonation of a 3.27 cm radius sphere of Tetryl in water at various initial pressures and densities. The calculation model used 1000 cells with the explosive initially resolved to 0.1 cm and the first 10 cm of water resolved to 0.25 cm. For the low initial pressure calculations, the water cell width was then increased to allow sufficient distance to follow the water shock during the time of interest. 

This resolution was adequate to ensure that the important features of the flow were mesh and viscosity independent. 

---

Potassium (metal) [7440-09-7] M 39.1, m 62.3 , d 0.89. Oil was removed from the surface of the metal by immersion in n-hexane and pure Et20 for long periods. The surface oxide was next removed by scraping under ether, and the potassium was melted under vacuum. It was then allowed to flow through metal constrictions into tubes that could be sealed, followed by distillation under vacuum in the absence of mercury vapour (see Sodium). EXPLOSIVE IN WATER. 

Several examples illustrate the use of GC/MS for analysis of explosives Trace analysis of explosives in water by GC/MS was carried out using a cooled temperature-programmable injector and a 15 mx 0.255 (Xm ID, 0.25 (Xm film thickness, DB-1 column [7]. 

A first approach to determining explosives on-site might include a combination of specialized sample-collection techniques and subsequent analysis using established IMS technologies or instruments. A second level of development could involve the fabrication of analyzers or analytical systems for an on-site operation and real-time analysis of samples. During the past several years, the first step of development has been demonstrated for explosives in water, in soils, and in a few unique uses. 

Sodium is extremely reactive. It reacts explosively in water as it releases hydrogen from the water with enough heat to ignite the hydrogen. The resulting compound of this reaction is sodium hydroxide (2Na + 2HjO —> 2NaOH + H T). Due to its extremely electropositive reactivity, there are few uses for the pure metallic form of sodium. Because of its reactivity, hundreds of sodium compounds are found on the Earth s surface. 

Aluminum chloride Al " + 3CP —> AlCl Aluminum chloride is a crystal that vaporizes in air and is explosive in water as it forms aluminum oxide and hydrochloric acid, as follows 2AlClj + dHjO —> Al Oj + 6HC1. Aluminum chloride is used as a catalyst in many organic reactions. 

Yinon J, Laschever M. 1982. Direct-injection chemical ionization mass spectrometry of explosives in water. European Journal of Mass Spectrometry in Biochemical, Medicine, and Environmental Research 2 101-104. 

The SeaDog sensor utilized in this work is capable of near real-time detection of low concentrations of explosives in water. The sensor utilizes novel sensing materials originally developed by collaborators at MIT. These materials are fluorescent polymers that are highly emissive when deployed as solid-state thin films. When the polymers interact with nitroaromatic explosives such as TNT, the fluorescence is quenched [3-5], The response of these materials to target analytes... 

Silvery needles refractive index 1.470 density 0.92 g/cm decomposes at 800°C decomposes explosively in water reacts violently with lower alco-hols dissolves in molten sodium and molten sodium hydroxide insoluble in liquid ammonia, benzene, carbon tetrachloride and carbon disulfide. 

Fig 24 Calculated Integral of p2dt vs Time at 10 Charge Radii, for Explosions in Water... 

Psillakis, E. and N. Kalogerakis. 2001. Solid-phase microextraction versus single-drop microextraction for the analysis of nitroaromatic explosives in water samples. J. Chromatogr. A 938 113-120. 

Belkin F, Bishop RW, Sheely MV. 1985. Analysis of explosives in water by capillary gas chromatography. J Chromatogr Sci 23 532-534. 

PsiUakis E, Mantzavinos D, and Kalogerakis N. Development of a hoUow fibre liquid phase microextraction method to monitor the sonochemical degradation of explosives in water. Anal. Chim. Acta 2004 501 3-10. 

McCutcheon SC, Medina VF, and Larson SL, Proof of phytoremediation for explosives in water, in Phytoremediation Transformation and Control of Contaminants, McCutcheon SC and Schnoor JL, Eds., John Wiley Sons, Hoboken, NJ, 2003, 429. 

Psillakis, E. and Kalogerakis, N., Solid-phase microextraction versus single-drop microextraction for the analysis of nitroaromatic explosives in water samples, J. Chromatogr. A, 938, 113-120, 2001. Petersson, M., Wahlund, K. G., and Nilsson, S., Miniaturised online SPE for enhancement of concentration sensitivity in capillary electrophoresis, J. Chromatogr. A, 841, 249-261, 1999. 

When immersed in water, the explosives in water-activated contrivances are initiated by electric current as water (acting as an electrolyte) immerses the electrodes of specially designed batteries by chemical reaction with water and by pressure sensors triggered at certain depths. These contrivances include ammunition, signal flares and other pyrotechnics, sounding devices (which are dropped by ships to determine depth), and actuating cartridges for gas cylinders that automatically inflate life rafts and jackets. 

Because of the reflection of sparse waves from free surface, the damage of explosion in water is obviously improved compared to that on ground. This property can be used to improve the utilization rate of explosives. But if the explosion occurs in deep enough water, the bubbles are dispersed or dissolved before they reach the free surface. Now there is no fountain. For general explosives, the depth is calculated by below equation. 

Here, h is the depth of explosives in water and W is the mass of explosives... 

Like the explosion on the ground, explosion in water increases the pressure of water shock waves. For rigid water bottom, it equals two times of explosion power. In fact, the water bottom is not absolutely rigid, and it absorbs part of energy. Experiments indicate that in the water bottom with sandy soils, shock wave pressure increases up 16 % and impulse goes up 35 %. 

Explosion hazard Fine powder can ignite in air Fine powder can ignite in air Na powder is highly explosive in water and may spontaneously explode in the presence of oxygen... 

---