There are two basic types of resin – cation-exchange and anion-exchange resins. Cation exchange resins will release Hydrogen (H+) ions or other positively charged ions in exchange for impurity cations present in the water.
Anion exchange resins will release hydroxyl (OH-) ions or other negatively charged ions in exchange for impurity anions present in the water.
A Typical two-bed Demineralised Water plant or DM Plant consists of FRP/MS Rubber lined Pressure vessels connected in series along with its internal fittings.
The first unit consists of high capacity strongly acidic cation exchange resin, which converts positive ions of salt and replaces them with hydrogen ions to form respective acids, which are absorbed in next vessel by strongly basic anion exchange resin. The water obtained by this process shows conductivity less than 20 µ S / cm at 250 C and total dissolved solids less than 10 ppm.