What is a common chemical used for water treatment in boilers?

Sodium phosphate is commonly used in water treatment for boilers primarily due to its ability to control scale and corrosion within the system. When heated, water can precipitate minerals, leading to scale formation, which can insulate heating surfaces and reduce efficiency. Sodium phosphate reacts with the calcium and magnesium present in the water, helping to prevent the formation of hard deposits, or scale, by keeping these minerals in solution. Additionally, it assists in maintaining a stable pH and can contribute to a protective film on metal surfaces, further minimizing corrosion.

The other substances listed, while they each have specific applications in water treatment or other processes, do not serve the same primary function in boiler systems as sodium phosphate does. For example, calcium chloride is more commonly used for de-icing and as a drying agent, sodium bicarbonate can be used to adjust pH levels but is less effective for scale control, and magnesium sulfate is typically utilized in different contexts, such as a laxative or in gardening, rather than for boiler water treatment. Thus, sodium phosphate stands out as the most relevant chemical for maintaining optimal conditions in boiler operations.