Hardness salts present in a water supply such as calcium and magnesium sulphate form what is commonly referred to as “limescale” or “scaling”. This can be seen as the scaling that occurs in kettles in hard water areas. This can cause serious operational problems where scaling within pipes reduces the bore and increases pressure losses. Hardness present in boiler feed supplies also leads to the need for more regular blowdown therefore leading to an increase in energy costs and water usage.

The hardness associated with calcium and magnesium salts can be easily removed by passing the feed water through a vessel containing strong acid cation resin which is operated in the sodium form. The resin has a higher affinity for calcium and magnesium over sodium so takes up these salts, replacing them with sodium to result in a balanced water which is free from the potential for scaling.

The resin has a finite capacity for softening and on exhaustion needs to be regenerated back in to the sodium form. This is carried out using a regenerant solution of saturated brine.