Smoke Producers

substances that yield persistent smoke or haze (aerosols) upon introduction into the atmosphere. They are intended for the production of smoke screens or signals.

Smoke producers used to produce smoke screens are divided into four groups according to their method of smoke formation. The first group includes substances that form haze upon diffusion or vaporization as a result of chemical interaction with atmospheric moisture and the formation of hygroscopic substances, which intensively absorb atmospheric moisture. This group consists of sulfuric anhydride, chlorosulfonic acid, solutions of sulfuric anhydride in sulfuric acid (oleum) or chlorosulfonic acid, and certain chlorides. These smoke producers may be used in smoke devices of various designs and, in some cases, artillery shells and mines.

The second group of smoke producers includes substances that produce smoke as a result of a reaction with atmospheric oxygen. White or yellow phosphorus is characteristic of this group. Upon combustion this substance, together with atmospheric oxygen, produces phosphoric anhydride, which interacts with atmospheric moisture and forms orthophosphoric acid, which intensively absorbs atmospheric moisture. This type of smoke producer may be used in shells, mines, and aerial bombs.

Substances that yield smoke that is formed during their volatilization or thermal breakdown (so-called pyrotechnic mixtures) constitute the third group. Substances that produce smoke as a result of volatilization and subsequent condensation include ammonium chloride, aromatic hydrocarbons (naphthalene, anthracene, and phenanthrene), and certain hydrocarbons of the aliphatic series. Pyrotechnic mixtures include metal chloride mixtures based on powdered metal oxides (zinc and iron) and various halogen derivatives (carbon tetrachloride and hexachloroethane). Pyrotechnic smoke producers are used in smoke pots and hand grenades.

The fourth group consists of various petroleum products and foam plastics. Petroleum products (diesel fuel, mazut, and solar oil) form smoke by vaporization and the subsequent condensation of the vapors in the atmosphere. They may be used in smoke machines and devices of various designs. To generate smoke from foam plastics, foam-forming resins are injected into a stream of gases whose temperature is higher than the temperature for producing the foam plastics them-selves. Drops of resin acquire a porous structure and harden, forming particles of smoke, whose dimensions in this case are significantly greater than usual.

Smoke signals are produced by using solid pyrotechnic mixtures containing a fuel, an oxidant, and an organic dye, which colors the smoke red, yellow, green, blue, violet, or black.