Foreign Removal

The propellant is dry-screened to remove dust and foreign material, and excess graphite. Unacceptable propellant from the dry-screen operation may be returned to the graining stage for reworking. The product is blended in large rotating barrels for baUistic uniformity. 

Lubricating oil used in intermittent service must show the least possible variation in viscosity with respect to temperature and must be changed at frequent intervals to remove the foreign matter collected during service. The stabiUty of such oil is therefore of less importance than the stabiUty of oil used in continuous service for prolonged periods without renewal. Lubricating oil for continuous service must be extremely stable because the engines in which it is used operate at fairly constant temperature without frequent shutdown. 

FoodApphca.tlons, Carbon dioxide, a nontoxic material, can be used to extract thermally labde food components at near-ambient temperatures. The food product is thus not contaminated with residual solvent, as is potentially the case when usiag coaveatioaal Hquid solveats such as methylene chloride or hexane. In the food iadustry, CO2 is not recorded as a foreign substance or additive. Supercritical solvents not only can remove oils, caffeiae, or cholesterol from food substrates, but can also be used to fractionate mixtures such as glycerides and vegetable oils iato aumerous compoaeats. 

In the wet method, as practiced in Colombia, freshly picked ripe coffee cherries are fed into a tank for initial washing. Stones and other foreign material are removed. The cherries are then transferred to depulping machines which remove the outer skin and most of the pulp. However, some pulp mucilage clings to the parchment shells that encase the coffee beans. Fermentation tanks, usually containing water, remove the last portions of the pulp. Fermentation may last from twelve hours to several days. Because prolonged fermentation may cause development of undesirable flavors and odors in the beans, some operators use enzymes to accelerate the process. 

A skin wound cleanser is a nonirritating, Hquid preparation (or product to be used with water) that assists in the removal of foreign material from small superficial wounds, does not delay wound healing, and may contain an antimicrobial ingredient. 

Tr ash removal—Removal of extraneous foreign matter from a processed material. Essentially a form of scalping operation. Type of screen employed will depend on size range of processed material—coarse, fine, or ultrafine. 

Isolation of the mills, use of nonsparldng materials of construction, and magnetic separators to remove foreign magnetic material from the feed are useful precautions (Hartman, Nagy, and Brown, U.S. Bur. Mines Rep. Invest. 3722, 1943). Stainless steel has less sparking tendency than ordinary steel or forgings. 

Remove detritus, trash, or accumulations of foreign material on a regular basis. 

Foreign bodies embedded in cake cause heat/sparks during removal (plowing out). 

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