Physical and Chemical Characterization of Military Smokes. Part 2. Fog Oils and Oil Fogs

This report describes a study of U.S. Army SGF-2 Fog Oils and the corresponding Oil Fogs using the Army M3-A3 Fog Generator to produce the fogs. The investigation included studies of the generation process, physical and chemical analysis of the oils and their fogs, and observations of the fog stability and persistence. It was noted that fog oil compositions varied from source to source and that this was reflected in the fog compositions. The generators did not appear to contribute significantly to fog variations. The fog oils and the fogs contained almost equal amounts of the aliphatic and aromatic hydrocarbons with acids, alcohols and esters at the 1% level or less and nitrogen derivatives in the parts per million range. Both the oils and their fogs proved to be too complex for complete chemical resolution by gas chromatography and mass spectrometry. Of the several hundred identifiable chemical species, aliphatic hydrocarbons were in the C14 - C22 range. The observed aromatics included one- through four-membered ring structures. The fogs were examined to determine size and stability. Size determinations indicated a mass median diameter of 1.16 micrometers with a standard deviation of 0.14 micrometers. On the basis of single particle counting, a bimodal distribution was observed with high levels of submicron particles. The aerosols were relatively stable; after aging for one hour, typical systems showed median particle size increases of the order of 12% with a decrease in the mass of suspended particles of about 30%. See also ADA080936.