Explosion point

Shock Wave A transient change in the gas density, pressure, and velocity of the air surrounding an explosion point. The initial change can be either discontinnons or gradual. A discontinnons change is referred to as a shock wave, and a gradual change is known as a pressure wave. 

These experiments are described in detail in Chapter 5, and will not be described further here. The overall conclusion, from an explosion point of view, is that flame speeds are relatively low, although atmospheric conditions alone may increase flame speed somewhat. The maximum flame speed observed for LNG was 13.3 m/s (China Lake), and for propane (Maplin Sands), 28 m/s. 

Blast wave Overpressure wave traveling outward from an explosion point. 

Blast - Is the transient change in gas density, pressure, and velocity of the air surrounding an explosion point. 

Note 1 Instead of heating the bar by gas burners, it can be heated electrically, such as described by E. Berl G. Rueff in Cellu-losechemie 14, 43 (1933). The bar, known as Bloc Maquenne, generally used in France for determining melting points, could be adopted for use in determining the ignition (or. explosion) point... 

Explosion Point — 297° when heated at the rate of 5°/min (Refs 4 St 10)... 

The limit may appear to be extraordinarily sharp. The stable velocity on one side of the critical limit may be quite small at the limit a stationary condition ceases to be possible and the reaction must accelerate thus, however small the velocity at a point just on one side of the limit, explosion takes place on the other side. The acceleration to the explosive point takes place in a time of the order of that required for chains to develop in the gas which may be an immeasurably small fraction of a second. Thus we have the remarkable phenomenon of a critical concentration limit, on passing which a very slow reaction suddenly changes into explosion. 

B4 or Type 2 Explosives. Lt grey powdery mixts of TNAns 60 or 70 w ith A1 40 or 30% used in Japanese incendiary submarine gun shells. The props of the 60/40 mixt were dl.90 (cast), power by ballistic pendulum 64%(PA= 100%), brisance by copper cylinder crusher 82% (PA=100%), explosion point 300 to 505°, impact sensitivity with 5-kg wt I7cm(max for no expins) and friction sensitivity 60kg(max pressure between two rubbing surfaces)... 

If a liquid is in equilibrum with air, a part of this liquid is in the vaporous state and shows a temperature-dependent partial pressure. At the boiling point, the partial pressure equals the pressure of the ambient air. The partial pressure versus temperature diagram is very close to an exponential shape (Fig. 1.1). LEL and UEL, as volumetric values, correspond to partial pressures Plel and Puel- And these values define - on the temperature axis - two points, the LEP (Lower Explosive Point) and the UEP (Upper Explosive Point), which say the same as LEL and UEL below LEP and above UEP, an explosive mixture cannot be formed. 

UEL Upper Explosive Limit LEP Lower Explosive Point... 

Described as explosion point heating rate S-10°/minute. 

If the temperature is constant, every false equilibrium is stable 428.-324. If the reactions are all adiabatic, the limiting false equilibria may be stable or unstable, 434.-325. Relation between the limiting false equilibria which are unstable and the explosive reactions, 427.—326. Three cases to distinguish, 437.-327. The reaction point of a mixture is, in general, below the explosion point, 429.—... 

To describe underground testing in some detail, we shall follow the report of Bouchez and Lecomte (1996) which describes the French nuclear testing in the Atolls of Mururoa and Fangataufa (French Polynesia). The measurements relating to the operation of the device were made in the immediate proximity of the explosion point. All the measuring instruments were housed in a container, the lower part of which contains the nuclear device. 

The cuttings from the borehole are analysed as drilling advances, in order to check whether the local geology is compatible with the scheduled nuclear test. If necessary, the planned depth for the explosion point can be increased until a favourable environment is encountered. 

The choice of the zero point is an essential element in the safety file of a nuclear test. However, this file covers many other aspects. It specifies the conditions for performing the test in conformity with the defined principles, in order to avoid accidents and ensure the radiological protection of the personnel and the environment. It must satisfy both the severe criteria for defining the explosion point and the many rules governing operational implementation. After examination and approval, this file becomes the reference document for the test in terms of safety. Any subsequent change necessitates a new examination. 

During an underground nuclear explosion, almost all the energy released is trapped in the first few tens of metres surrounding the explosion point. The energy is mainly absorbed by the vaporization of the rock in the immediate vicinity of the explosion point, then by the fracturing of the material. Beyond a certain distance, known as the elastic radius , the shock wave is sufficiently attenuated for the movements to be reversible after the wave has passed, the material returns to its initial state. All that... 

Because of the continuous presence of seismic background noise, only explosions whose yield exceeds a certain value are detected. This detectability limit varies with the distance from the explosion point and increases with the amplitude of the background noise. In the case of the Pacific Test Centre, the station at Rarotonga (Cook Islands), located at approximately 2000 km on a direct uninterrupted line from Mururoa, receives the T waves emitted by weak explosions and thus has a detectability close to one kiloton. The other stations are much further away and, apart from a few particularly sensitive stations such as the Yellowknife network in Canada, they have a much higher detectability limit. 

Diazidodiphenylsulfane.or Bis(4>Azido phenyl)-sulfane, NgCgH. SOj.CjH Ng, mw 300.30, N 28.03%, crysts (from acet), mp 156—57°(explosion point). It was prepd by diazotizing bis(4 aminophenyl)-sulfone in aq sulfuric acid and treating the diazonium soln with a cold soln of hydrazine hydrate Na acetate (Refs 1 2)... 

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