What is the purpose of adding caustic soda to boiler water?

Adding caustic soda (sodium hydroxide) to boiler water serves a critical role in maintaining the proper pH levels within the boiler system. The primary purpose of regulating the pH is to prevent the formation of corrosion and scale within the boiler and its piping. Corrosion can lead to significant damage and inefficiency, while scale build-up reduces heat transfer efficiency, potentially leading to overheating and boiler failure.

By increasing the pH of the boiler water, caustic soda helps create a more alkaline environment, which is favorable for protecting the metal surfaces of the boiler from corrosive compounds, particularly in high-pressure systems. This balance is crucial for ensuring safe and efficient operation, as it allows for the proper functioning of water treatment programs in place to handle impurities and maintain optimal water quality.

While the other options touch on various water chemistry and physical properties, they do not relate directly to the primary function of controlling pH in this context. For instance, enhancing thermal conductivity, increasing water viscosity, or reducing water temperature are not relevant purposes of adding caustic soda to boiler water. Instead, maintaining appropriate pH is fundamental to preserving the integrity and efficiency of the boiler system.