Military filters

The main applications of the carbon support include hydrogenation reactions (Pd/C, Pt/C, Pt-Fe/C, Fe-Ru/C, Fe-Co/C, Ni/C/Co/C), oxidation reactions (Sn/C, Ni/C), and environmental automotive catalysis (Cu/C, Cu-Cr/C) [341], The examples of carbons working as catalyst supports are discussed in the following chapters. The best known examples are whetlerites used for military filters... 

Hence the first military filters were individual filters fitted on gas masks. During WWI they were not always used exclusively by soldiers...(see Fig.4,5). This type of filter is basically a bed of activated carbon, arranged in such a way that one gets a linear flow of contaminated air through the bed (see Fig.6). However, the actual use of this of filter involves some problems. 

Fig.6. Picture of a cross-section of an individual military filter...

As TEDA is present on all modem types of whetlerite, military filters exhibit a rather good retention of radioactive gases by direct chemisorption. However, one has to bear in mind this is only a retention, not a destruction. This means that the filter itself will become a radioactive source, much like when retaining radioactive aerosol particles (see section 2.3.8), and has to bo replaced, and disposed of, as soon as possible. 

From the previous sections it is clear that military filters filled with whetlerite carbon retain most industrial vapours and gases at least as eifectively as dedicated industrial filters, especially when the supplementary impr nation with TEDA is added. This is also illustrated in Fig.l5, where the breakthrough times for a number of gases of some typical military filters (filled with whetierites) are compared with the minimum requiremoits of an industrial filter ABEK-2, tested confoim the European Standard EN141 [83]. This norm describes the testing conditions and requirements of the most common types of industrial filters. The data presented arc for tests with a flow rate of 30 litres/min, an inlet concentration of 5000 ppmv and a relative humidity of the air stream of 70%. 

Fig.l5. Comparison between an industrial filter type ABEK-2 and some typical military filters regarding the protection against certain industrial compounds... 

Filters have been extensively used in households and industry for removing particles from air or liquid. In the case of enviromental protection filters are used to remove pollutants from air or water. In military, filters are used in uniform garments and isolating bags to decontaminate aerosol dusts, bacteria, while maintaining permeability to moisture vapor for comfort. A respirator is another example requiring an efficient filtration function. The same properties are also needed for some fabrics used in the medical field. ... 

Initially, DADC polymers were used in military aircraft for windows of fuel and deicer-fluid gauges and in glass-fiber laminates for wing reinforcements of B-17 bombers. Usage in impact-resistant, lightweight eyewear lenses has grown rapidly and is now the principal appHcation. Other uses include safety shields, filters for photographic and electronic equipment, transparent enclosures, equipment for office, laboratory, and hospital use, and for detection of nuclear radiation. 

Covers 250 non-electronic part types such as 87. actuators, complings, filters for 12 classes of environment (air, ground, sea) used in military systems and equipment... 

Note For military personnel engaged in training scenarios the M9, M17 or M40 series masks are acceptable. Filter elements and canisters should be changed after each use with DS2. 

The ECOCHOICE process can be used for treating drinking water, groundwater, industrial wastewater, landfill leachates, and bio-filter effluent. ECOCHOICE has been used at a groundwater treating operation at a military site in Tennessee to treat nitroaromatics. 

A product which contains about 2.5 ethoxy groups (47—48%) is thermoplastic and is suitable for commercial and military uses its sp gr is 1.07—1.18, nD 1.47 and softening point 240—45°. It can be prepd in a laboratory, by slowly adding (with stirring) to the pulped filter paper (suspended in 44% aq NaOH so In maintained at 100°) an excess of ethyl chloride (usually 6 moles per one mole of cellulose) and allowing to stand for a while Note In order to obviate to some extent the side reactions of hydrolysis, the procedure is conducted in the presence of large amount of NaCl... 

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