he importance of starting with clean grain when creating a distilled spirit is of the utmost importance. For grain to be clean, it needs to be free of plant residue, inferior kernels, and kernels of undesired types of grains. To ensure that the grain meets the quality levels desired, the key is to start with a high-quality product straight from the field. Modern farm machinery is able to produce a much cleaner product than was possible in the past. Growing conditions, however, often result in low quality kernels mixed in with the good kernels. Therefore, almost all harvested grain can benefit from being cleaned mechanically. A variety of machines can be used to sort grain by size, weight, density and, in some cases, by its visual appearance. Sometimes only one machine is needed to reach the quality level desired; more often though, there is a progression of machines used to make a final product. The first machine used in the grain cleaning process is usually a fan mill. These cleaning machines will sort the grain according to size and remove any plant residue using air movement and perforated screens. The fan mill cleaning process begins when the grain enters a small holding tank that regulates the flow of grain. When the grain leaves this tank, it is in a slow, steady stream so that air blowing from a fan is able to remove any plant residue from the grain. After this short fall, the grain lands on a set of dual screens. These screens are set at a decline, and shake constantly so that the grain moves across them. Of the two screens, the top screen has holes that are large enough that the grain should fall through it. This leaves only large contaminants on top of the screen, where they are disposed of. Once on the second screen, the grain continues to slide across it, but in this case, the holes in the screen are sized so that the grain should WWW.ART ISANSP IRITMAG.COM â€
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not fall through them. Therefore, small contaminates fall through and are removed. Once the grain has been across this initial set of screens, it is common for it to proceed to a second set of screens. This set of screens will repeat the process that the first set performed, but with holes being closer to the ideal grain size. Once the grain has finished moving across these screens, it will once again be subjected to air blown by fan. This time, the air movement will be stronger and designed to remove underweight kernels, which tend
to be of poor quality. With the use of the two fans and multiple sets of screens, the fan mill should produce a final product of the correct size and free of plant residue. It is common for a fan mill to remove 10-15 percent of the original grain supply. If the grain is initially of high quality, that may be all the cleaning needed to produce a satisfactory product. A second machine that is often utilized after a fan mill is called a gravity table. It sorts the grain by density. This sorting is most important when dealing with grains
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