وسائل الكشف عن الاسلحة الكيميائية : بطريقة الكواشف الورقية : أوراق الكشف Manual Detection Methods Detection Paper Detection paper is based on certain dyes being soluble in CW agents. Normally, two dyes and one pH indicator are used, which are mixed with cellulose fibres in a paper without special colouring (unbleached). When a drop of CW agent is absorbed by the paper, it dissolves one of the pigments. Mustard agent dissolves a red dye and nerve agent a yellow. In addition, VX causes the indicator to turn to blue which, together with the yellow, will become green/green-black. Detection paper can thus be used to distinguish between three different types of CW agents. A disadvantage with the papers is that many other substances can also dissolve the pigments. Consequently, they should not be located in places where drops of, e.g., solvent, fat, oil or fuel can fall on them. Drops of water give no reaction. On the basis of spot diameter and density on the detection paper, it is possible to obtain an opinion on the original size of the droplets and the degree of contamination. A droplet of 0.5 mm diameter gives a spot sized about 3 mm on the paper. A droplet/cm2 of this kind corresponds to a ground contamination of about 0.5 g/m2. The lower detection limit in favourable cases is 0.005 g/m2.
Posted on: Mon, 26 Aug 2013 20:27:44 +0000
Trending Topics
Recently Viewed Topics
© 2015