What chemical is often used to control corrosion in boiler systems?

Phosphate is commonly utilized in boiler systems to control corrosion due to its ability to form protective layers on metal surfaces. When added to the water in a boiler, phosphates react with calcium and magnesium ions to produce insoluble compounds that precipitate out of the solution. This precipitation not only helps to prevent scaling but also creates a barrier that protects metal surfaces from corrosion.

In addition, phosphates can help maintain alkaline conditions in the boiler water, which is vital for minimizing the corrosive effects of acidic substances that may be present. The formation of a protective phosphate layer is crucial in helping to prolong the life of boiler components and enhance overall system efficiency. Properly managing phosphate levels is therefore an essential practice in water treatment for steam and hot water boilers.

While the other chemicals listed might have various uses in water treatment, they do not specifically target corrosion control in the same effective manner as phosphates. For instance, calcium chloride is typically used for water softening, sodium carbonate is primarily a pH adjuster, and silicate can help in scale control but is less effective at corrosion inhibition compared to phosphates.