Explosion dust particle size measurements

Abstract

In situ measurements of the sizes and concentrations of dust particles generated by the detonation of high explosives in clay soil near Leesville, La., sandy clay soil near Huntsville, Ala., and sandy soils near Orogrande, N.M. are reported. Measurements were generally made within 1 m of the surface (in one case 10 m) at distances ranging from 10 to approximately 50 m from the detonation point with a combination of Knollenberg lightscattering counters (for particles with equivalent radius in the submicron to 15-microm range) and a Knollenberg optical array probe (for particles of 10-150 microm). Measurements were made for periods of several tens of seconds following detonation. All dust size distributions, irrespective of soil or explosive type, exhibit a bimodal character with mass mean radii of approximately 7 and 70 microm. Peak aerosol mass loadings inferred from the distributions have values ranging from 0.05 to 10 g gm-3 with the larger mode of particles contributing most to the mass loading. Predictions of dust extinction coefficients at visible (0.55-microm) and IR (10.4-microm) wavelengths were made using the measured size distributions together with estimates of dust refractive indices. These predictions suggest that extinction should be nearly neutral (wavelength independent) in agreement with transmission measurements made during some of the tests. Predicted mass extinction coefficients, under the assumption of dust material density of 2.5 g cm-3, are of the order of 0.05 m2 g-1 at both visible and IR wavelengths. This value is also in good agreement with a test-averaged measured value of 0.03 m3 g-1 (at lambda = 10.6 microm) obtained using a short path transmissometer and hi-vol sampler.

Performance of laser and radar ranging devices in adverse environmental conditions

“…To quantify the suspended dust loading, the transmissibility of the obscurant media was measured via the attenuation of the signal from 1-mW red laser pointers placed at various distances (≈6, 17, 25 m) along the test chamber. A similar method was used successfully in the past by Pinnick, Fernandez, and Hinds (1983), which compared the transmission of visible and infrared signals at specific frequencies through explosion-generated dust, as well as using a plethora of independent measurement techniques (Hi-Vol sampling and subsequent lab analysis, Knollenburg counters of various sensitivities and measurement principles) to characterize the dust.…”

Evolution Of A Suite Of Smart Millimetre Wave Radar Systems For Situational Awareness And Automation In Mines

“…An interesting characteristic of almost all measured dust clouds is that the distribution of particle sizes is bimodal, as illustrated in Figure 4. This is apparently independent of the source of the dust, as it has been measured for wind blown dust (Patterson 1977;Pinnick, Fernandez et al 1985), vehicle generated dust and dust generated by explosions (Pinnick, Fernandez et al 1983). Unexpectedly, the distribution holds irrespective of the density of the dust cloud, though the proportions may change.…”

Estimation of health hazards resulting from a radiological terrorist attack in a city

“…This was in general found to produce a particle size spectrum with much of the contaminant mass in the 30-100 µm range, and a smaller peak in the range of a few microns. This type of size distribution was also measured in US blast experiments impacting on soil (Pinnick et al, 1983), and after the Thule accident in 1968. The Thule explosion was essentially similar to that of a 'dirty bomb': a conventional explosion dispersing a solid, quite possibly ceramic, radioactive material with a very high melting point.…”