Scale inhibitors are chemicals, which inhibit the nucleation and growth of hardness scale crystals. There are three main types of scale inhibitors in current use that include polyphosphates, phosphonates and organic polymers. Scale inhibitor is used for resorted to prevent the precipitation of inorganic salts, including barium/strontium/calcium sulfates, calcium/barium magnesium carbonates and calcium fluoride. Growth of crystals or the nucleation of crystals can be inhibited by the addition of scale inhibitors. It is used as inorganic mineral scale controller in sugar evaporators. It may also interfere with the crystallization phenomena by blocking the sites available for crystal growth and prevent the adhesion of scales to metal surfaces.