Dispersion tests

Numerous documents detail tests of chemical shells at the Spring Valley site. Some shells were attached to the top of poles or placed in the ground and fired electrically. Others were fired from mortars designed to detonate on impact. In either case, glass bottles were placed on the ground or in circular trenches to establish the concentrations of the heavier-than-air gas at known distances from the shell explosions so that the effects on dogs could be assessed accurately. 

The District found trench maps and test reports from Spring Valley indicating that many Livens projectiles as well as smaller 75-mm artillery shells were tested with poison gas. In particular, they noted tests with arsine and magnesium arsenide. Arsenic is very heavy and settles rapidly to 

the point is that many POIs were not properly assessed against current knowledge. For another example, one POI— identified previously was the Old Mustard Field— was a 500-ft diameter circle covered repeatedly with mustard gas, a known carcinogen. This area has not been surveyed for buried containers of mustard or for polymerized mustard. 

Applications. Considering that many properties of filled materials depend on the quality of dispersion, the reasons for conducting dispersion tests are self explanatory. 

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Numerous tests on dispersion of heavy gases and on causes of UVCEs have been performed in recent years. Dispersion tests and computer models based on them may not be representative of all... 

The Britter and McQiiaid model was developed by performing a dimensional analysis and correlating existing data on dense cloud dispersion. The model is best suited for instantaneous or continuous ground-level area or volume source releases of dense gases. Atmospheric stability was found to have little effect on the results and is not a part of the model. Most of the data came from dispersion tests in remote, rural areas, on mostly flat terrain. Thus, the results would not be apphcable to urban areas or highly mountainous areas. 

Example 2 LNG Dispersion Tests Britter and McQnaid (1988, p. 70) report on the Burro LNG dispersion tests. Compute the distance downwind from the following LNG release to obtain a concentration equal to the lower flammability limit (LFL) of 5 percent vapor concentration by volume. Assume ambient conditions of 298 K and 1 atm. The following data are available ... 

Table 2.7 lists techniques used to characterise carbon-blacks. Analysis of CB in rubber vulcanisates requires recovery of CB by digestion of the matrix followed by filtration, or by nonoxidative pyrolysis. Dispersion of CB within rubber products is usually assessed by the Cabot dispersion test, or by means of TEM. Kruse [46] has reviewed rubber microscopy, including the determination of the microstructure of CB in rubber compounds and vulcanisates and their qualitative and quantitative determination. Analysis of free CB features measurements of (i) particulate and aggregate size (SEM, TEM, XRD, AFM, STM) (ii) total surface area according to the BET method (ISO 4652), iodine adsorption (ISO 1304) or cetyltrimethylammonium bromide (CTAB) adsorption (ASTM D 3765) and (iii) external surface area, according to the dibutylphthalate (DBP) test (ASTM D 2414). TGA is an excellent technique for the quantification of CB in rubbers. However, it is very limited in being able to distinguish the different types of... 

Toxicologic Assessment of the Army s Zinc Cadmium Sulfide Dispersion Tests (1997)... 

McGrath, R. N. and Lin, D. K. J. (2002). A nonparametric dispersion test for unreplicated two-level fractional factorial designs. Journal of Nonparametric Statistics, 14, 699-714. 

In addition, the ringed loads showed considerably less lateral dispersion. Test groups were ft red from a bench rest at 25, 50, and... 

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