Asbestos fill packing

Cellular Film Asbestos fill packing that converts water droplets into a thin molecular filter for more efficient cooling. Less static pressure is encountered than with splash-bar fill, thus permitting the use of higher air velocities. 

This is done in a snout-ended tube (see Fig. 67) with an asbestos plug packed in the snout and timed to allow a rate of flow of air of about 15 c.cs. per minute. A filling of about 24 cms. of wire-form CuO is used, and this is held in place by a small asbestos plug. Behind the boat is placed a short CuO gauze spiral. 

The saturated calomel electrode (SCE), which is constructed using an aqueous solution saturated with KCl, has a potential at 25 °C of -hO.2444 V. A typical SCE is shown in Eigure 11.8 and consists of an inner tube, packed with a paste of Hg, HgiCli, and saturated KCl, situated within a second tube filled with a saturated solution of KCl. A small hole connects the two tubes, and an asbestos fiber serves as a salt bridge to the solution in which the SCE is immersed. The stopper in the outer tube may be removed when additional saturated KCl is needed. The shorthand notation for this cell is... 

About 20 gms. of manganous carbonate are made into a thick paste with water in a basin. This is stirred with an equal bulk of pumice in small pieces, and then placed in an air oven at 110°—120° until quite dry. When dry it is loosely packed into a combustion tube, sufficient being taken to fill rather more than half (40 cms.) the length of the tube two asbestos plugs are used to keep the layer in position. 

Behind the packing plug in a snout-ended tube, a Ag gauze spiral (5 cms.) is placed and held in position by a layer of asbestos (0-5 cm.). A filling of a mixture of wire-form CuO and PbCr04 is inserted and held in place by an asbestos plug (0-5 cm.). Between the boat and this last plug is another Ag spiral (5 cms.). The combustion is carried out in much the same manner as described for C—H compounds. 

Apparatus. A pyrex tube D, 50 cm. in length and 4 cm. in diameter (Fig. 29), is filled with approximately 300 g. of platinized silica gel packed at each end with a plug of glass wool. The catalyst tube is wrapped with asbestos paper and placed in the electric furnace E. The tube is drawn down at each end, and a 200-ml. distilling flask B... 

Cocoa fat and lipids The lipid components in cocoa are extracted into petroleum ether by either the Knorr Tube method or by Soxhlet extraction. Both are adopted by AOAC, and the latter method by both AOAC and the Office International du Cacao et du Chocolat. In the Knorr Tube method, 2-3 g of cocoa powder or grated chocolate product is transferred into a Knorr Tube fitted with 6 mm of tightly packed mat of washed asbestos filter. The extraction tube is connected to suction by a two-way stopcock, and the stem of the extraction tube is connected to a preweighed Erlenmeyer flask. The extraction tube is filled up to two-thirds capacity by petroleum ether. 

Some cooling towers operate with natural draft. This is possible because the warmer, humid air inside the tower is less dense than the colder, drier outside air. Many such towers are hyperbolic and may require an overall height of 220 ft. The fill used in such a column must be quite open to avoid any significant pressure drop. Such fill can have a tee- or vee-shaped cross section molded from perforated plastic sheets. Corrugated sheets made of asbestos and cement are popular in large natural draft towers. A ceramic cellular block that is stacked into the tower also is used. These fills, however, provide a small interfacial area per cubic foot so mass transfer is rather low per foot of packed depth. 

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