Acceptable Levels of Alkalinity
Alkalinity, like hardness and TDS, is expressed as parts per million (ppm). The acceptable level of alkalinity in a boiler depends largely upon the pressure that the boiler will be operating at. In a low pressure boiler, this level
should not exceed 700 ppm. If the alkalinity level exceeds 700 ppm it may result in a breakdown of the bicarbonate producing carbonate and liberate free carbon dioxide with the steam. This presence of carbon dioxide will corrode steam and return lines.
THE MAXIMUM ALLOWABLE CONCENTRATION OF ALKALINITY WITHIN A LOW PRESSURE BOILER IS 700 PPM.
Dealkalization is the process in which softened water is passed through a treatment tank that contains an anion resin. This anion resin removes anions such as sulfate, nitrate, carbonate and bicarbonate. These anions are then
replaced by chloride. Sodium chloride (salt) is then used to regenerate the unit with the anion exchange resin.
Hard water has the ability to precipitate calcium carbonate and magnesium hydroxide within a dealkalizer, therefore it is necessary to have softened water
fed to the system. In addition, the anion exchange bed is susceptible to fouling due to suspended solids. dealkalizer. The resin in a dealkalizer is lighter than that found in a water softener. This means that the backwash rate will be much slower and insufficient to remove any suspended material.