What is phosphate used for in a boiler system?

Phosphate is primarily utilized in boiler systems to control scale formation and enhance water quality. When added to the water in a boiler, phosphate reacts with calcium and magnesium ions, which are common impurities that contribute to scale buildup on the internal surfaces of the boiler. This reaction forms a non-adhering sludge that can be more easily removed from the system. By preventing scale formation, phosphates help maintain efficient heat transfer and prolong the life of the boiler, as scale can lead to overheating and potential failures.

The other options do not accurately describe the role of phosphate in a boiler system. For example, phosphate does not function to reduce pressure or increase temperature, as those aspects are managed through other operational controls and design features of the boiler. While phosphate can play a role in water treatment, its main purpose isn't directly to purify water but rather to manage hardness and scaling issues.