Screening smokes phosphorus smokes

A third screening smoke-type is white phosphoms [7723-14-0] (WP), P (see Phosphorus and THE phosphides), which reacts spontaneously with air and water vapor to produce a dense cloud of phosphoms pentoxide [1314-56-3]. An effective screen is obtained as the P2O5 hydrolyzes to form droplets of dilute phosphoric acid aerosol. WP produces smoke in great quantity, but it has certain disadvantages. Because WP has such a high heat of combustion, the smoke it produces from bulk-filled munitions has a tendency to rise in pillarlike mass. This behavior too often nullifies the screening effect, particularly in stiU air. Also, WP is very brittle, and the exploding munitions in which it is used break it into very small particles that bum rapidly. 

Phosphorus pentoxide reacts with moisture in the air to form phosphoric acid. WP munitions were used by U.S. military forces and their allies to mark targets and to provide smoke screen coverage for troops and equipment in combat zones. These munitions were produced primarily by the dip-fill or wet-fill method illustrated by Figure 1. The method is called dip-fill because empty munition bodies are dipped below the molten phosphorus level in an open tank until the munitions are filled with liquid phosphorus. The method is also called wet-fill because a water overlay is maintained over the liquid phosphorus (in the fill tank) to prevent spontaneous combustion of the chemical element and because the filled munition will have a slight water overlay (up to 1/8" column height allowed). 

The TOP values of some well-known smokes given in the literature [28] suggest that the phosphorus class of smokes are most effective for screening and hence are used during military operations. 

The smokes produced by WP and RP have large yield factors for various relative humidities. This means that the inference derived on the basis of TOP values of various types of smokes is also supported by the yield factor values, that is, the screening efficiency of the phosphorus class of smokes is maximum. 

Berkowitz JB, Young GS, Anderson RC, et al. 1981. Research and development for health and environmental hazard assessment, Task Order 5. Occupational and environmental hazards associated with the formulation and use of white phosphorus-felt and red phosphorus-butyl rubber screening smokes. Cambridge, MA Arthur D. Little, Inc. DAMD17-79-C-9139. AD-A116956. 

Spanggord RJ, Podoll RT, Renwick RT, et al. 1983. Environmental fate of white phosphorus/felt and red phosphorus/butyl rubber military screening smokes Phase I -Literature review. Final Report. SRI International, Menlo Park, CA. Contract No. DAMD17-82-C-2320. AD-A150 754. 

The greater part of the elemental phosphorus produced in this country is used in the manufacture of a type of alloy known as phosphor bronze. In chemical warfare, smoke screens have been produced by the... 

Investigation of those overexposed to screening smokes should include, at least, chest radiograph, pulmonary function tests, arterial oxygen tension measurement, blood clinical chemistry, sputum culture, ophthalmic examination with slit-lamp biomicroscopy, and possibly measurement of intraocular pressure. If available, CT scan may be used to assess the severity of lung injury (Hsu et al., 2005). With some smokes, notably white phosphorus, there may be skin contamination with severe irritation and penetrating bums the management of white phosphoms skin burns is discussed in detail in Section VI.A.2. 

Davies, N., Red phosphorus for use in screening smoke compositions. Pentagon Reports, 1999. http /www. strormingmedia.us/76/7632/A763273.html... 

USE White phosphorus manuf rat poisons for smoke screens, gas analysis. Red phosphorus pyrotechnics manuf safety matches in organic synthesis manuf phosphoric acid, phosphine, phosphoric anhydride, phosphorus pencachlo-ride, phosphorus trichloride manuf fertilizers, pesticides, incendiary shells, smoke bombs, tracer bullets. 

L. A. Prohammer, and D. R. Kalkwarf. 1986. Acute toxicity of smoke screen materials to aquatic organisms, white phosphorus-felt, red phosphorus-butyl rubber and SCG No. 2 for oil. Energy Res. Abstr. 77(15), Abstr. No. 34982 cited in Chem. Abstr. CA 106(19) 150923Z. 

Phosphorus occurs in three allotropic forms white, red, and black. Of these, white phosphorus was used most often during World War II in military formulations for smoke screens, marker shells, incendiaries, hand grenades, smoke markers, colored flares, and tracer bullets. 

Because of the toxicity associated with the manufacture of white phosphorus and because of its field risks, a gradual shift to red phosphorus (95% phosphorus in a 5% butyl rubber base) was undertaken after World War II. The British smoke grenade (L8-Al-3), which used red phosphorus, produced adequate field concentrations of smoke and functioned as an effective tank screen. Oxidation of red phosphorus produces a variety of phosphorus acids that, on exposure to water vapor, produce polyphosphoric acids. These acids may produce mild toxic injuries to the upper airways that result in a cough and irritation. There are no reported deaths resulting from exposure to red phosphorus smokes. Therapy... 

Where screening smoke must be delivered by explosive action, and where at the same time smoke screens without fire hazard are desired, a solution of 55 parts of sulfur trioxide (SO3) in 45 parts of chlorosulfonic acid (CLSOjH) is cheap and effective though its screening power is about one-half or less that of phosphorus. This FS mixture and the more expensive and otherwise less desirable titanium tetrachloride (TiCL4) called FM become aerosolized droplets only in the presence of water and presumably display their power of obscuration best and fastest in humid air. 

That the reputation of smoke increased on Luzon is suggested by the following entry in a 6th Infantry Division operational report "The outstanding use for chemical warfare weapons in the Shimbu Line battle was the use of screening smokes... . One of the mortar battalions called attention to the high ratio of white phosphorus used on Luzon, indicative of quite a departure from previous Pacific practice. 

Benjamin C. Macintire, Navy 5-inch Smoke Projectile, WP-Filled, Engineering Tests. EATR 338, 8 Apr 41. (2) H. F. Johnsron, Plasticized White Phosphorus, in Military Problems with Aerosols and Nonpersistent Gases. Summary Tech Rpt of Div 10, NDRC (Washington, 1946). (3) Noyes, Chemistry, pp. 277-78. (4) CWTC Item 1514, Standardization of Screening Smoke, PWP, 20 Dec 45. 

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