Rotameters are otherwise called variable region digital flow meters. Variable zone flow meters work by measuring the stream rate as the liquid goes through a decreased tube where the cross sectional region of the tube steadily gets to be more prominent as the liquid goes through the tube. The term rotameter originates from the early form of the buoys, which had spaces to balance out and focus them inside of the liquid stream. This made the buoys turn. Current buoy outlines are an assortment of shapes (round for instance) and are built of stainless steel, glass, metal, and plastic.