Descaling agent

A descaling agent or chemical descaler is a chemical substance used to remove limescale from metal surfaces in contact with hot water, such as in boilers, water heaters, and kettles. Descaling agents are typically acidic compounds such as hydrochloric acid that react with the alkaline carbonate compounds present in the scale, producing carbon dioxide gas and a soluble salt. Strongly acidic descaling agents are often corrosive to the eyes and skin.

Notable descaling agents include acetic acid, citric acid, glycolic acid, formic acid, phosphoric acid, sulfamic acid and hydrochloric acid.

There are many companies offering inhibited or "buffered" acids that inhibit the corrosive effect of the acids on various materials. Typically about a 10% concentration of hydrochloric acid with a corrosion inhibitor and some added penetrating and wetting agents added. This allows for a better cleaning of machinery and especially heat exchangers because often the scale is mixed up with silica and other contaminants. These additives reduce the corrosion on the metals and cut through and loosen up these other materials mixed with the scale for faster and more thorough cleaning.

See also

• Dealkalization of water
• Hydronics
• Pickling (metal)
• Water softening