The most convenient arrangement of screens, screening by selection, is a cascade series above the storage bins with removal of the finest fraction first (Fig. 1). Undersize fractions may then drop directly into bins but the greatest wear is suffered by the most delicate, finest mesh. A vertical array of meshes removing the coarsest fraction first, screening by rejection, can be achieved simply in a multiple deck screen or cascade of screens but provision must now be made for transport of oversize or undersize fractions respectively. A common compromise is to employ a splitter screen to divide the total feed into coarser and finer fractions, often at about 20 to 28 mm, followed by screening by selection.
FIG. 1. Arrangements of inclined vibrating screens:(a) sizing by selection;(b) sizingby rejection;(c) use of splitter screen.