Critical diameter

Reactivity (instability) information Acceleration rate calorimetry Differential thermal analysis (DTA) Impact test Thermal stability Lead block test Explosion propagation with detonation Drop weight test Thermal decomposition test Influence test Self-acceleration temperature Card gap test (under confinement) JANAE Critical diameter Pyrophoricity... 

Since the size range of the particles to be removed is less than the critical diameter, we are confident that the particles will follow Stokes law. Hence, the settling velocity for a 50 ft size particle is ... 

Whether a flame is transmitted through a flame arrester depends on the length and aperture size of the arrester, the approach velocity of the flame, the pressure rise, and the temperature of the arrester (Wilson and Flessner 1978). Wilson and Flessner state that the evidence indicates that low-speed flames can be quenched by an array of small passageways placed in a duct, provided that the effective passageway diameter (critical diameter) meets the following criterion ... 

Low-speed flames will only be quenched if die passageway diameter is below a certain critical value. This critical diameter can be calculated by the following equation (Mendoza et al. 1996) ... 

Gas or Vapor Critical Diameter (mm) Gas or Vapor Critical Diameter (mm)... 

The experimental values of the critical diameter were determined over a wide range of temperatures and pressures. 

The measurements were made using different experimental apparatus such as narrow pipes, diaphragms with a round hole, flat slots, etc. Values of the critical diameter determined using noncircular apertures have been converted to equivalent circular apertures. 

The critical diameter above which the flooding velocity is independent of diameter is given by ... 

Critical Diameter. The crit diam for deton propagation in iron tubes is 25mm, in brass 7mm (Ref 31)... 

Analytical A proc is described for the quant titrimetric analysis of TeNMe in nitric acid (Ref 35)s and a spectrophotometric method is described in Ref 41 for the detn of small amts of TeNMe in air and w Critical Diameter. The crit diam for deton propagation of TeNMe thickened with poly-(methyl acrylate) and loaded with up to 75% inert solids was detd and found to decrease with increasing solids loading. It was postulated that the solids acted as reaction foci ahead of the deton front (Ref 45)... 

Regardless of any theory, there is firm exptl proof that the particle size of a granular expl affects its steady detonation properties as well as its initiation behavior. In particular, the detonation velocity as well as the critical diameters of many granular expls depend on their particle size. The shock sensitivity of granular expls is also influenced by particle size. These effects will now be described Steady Detonation. 

Fig 2. Critical diameter of TNT as a function of initial density. 1. Pressed or powder after Andreev and Belyaev (1960) (Ref 6). 

The critical diameter, dc, of many insensitive granular expls increases with increasing particle size. This is shown in Fig 2 for TNT and the following tabulation for Picric Acid and for Ammonium Perchiorate... 

There are few quant data for D vs d for PETN. However, it is certain that the diameter effect for PETN is quite small. This becomes apparent when one considers that the critical diameter for PETN (at p = 1 g/cc and 0.025-0.1 mm particle size) is only 0.9mm (Bobelev quoted in Ref 22, p 348), and becomes smaller at p> 1. Cook et al (Ref 18) show that D varies from about 4800m/sec at d=0.32cm to 5400 m/sec at d> 1.6cm, for —65 to +100 mesh PETN at 0.95g/cc. Since confinement effects parallel diameter effects, D for PETN is almost independent of confinement for any practical size charges. 

Critical Diameter (which will propagate a detonation). The min diam for dry AP, wet with acet, and wet with et ale, was found to be under 2 inches when confined, and under 4 inches when unconfined (Ref 24)... 

Critical diameter, dc, is the diameter below which steady detonation is impossible. For PA,... 

Pressure, Detonation. Detonating condensed expls develop very-high pressures. For most military expls and many of the commercial expls the pressures attained within the expl column do not depend on confinement, provided the column diameter is appreciably larger than the critical diameter of the expl. This confinement-independent pressure associated with a steady detonation is called the Chapman-Jouguet pressure or PCJ... 

Propellant Density (g/cc) Diameter (cm) Critical Diameter (cm) Detonation Velocity (km/sec) Detonation Pressure (kbar) Ref... 

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