Which addition is used specifically to prevent corrosion and scaling in boiler water?

Sodium sulfite is used specifically in boiler water to prevent corrosion and scaling. It acts as an oxygen scavenger; when sodium sulfite is added to the boiler water, it reacts with any dissolved oxygen present, preventing it from causing corrosion in the boiler components. By removing oxygen from the water, it helps to safeguard the metal surfaces from rusting, thereby extending the lifespan of the boiler system.

The use of sodium sulfite is particularly important in high-pressure systems where the potential for corrosion is heightened due to elevated temperatures and pressures. Moreover, sodium sulfite does not contribute to scaling, unlike some other additives.

In contrast, sodium chloride can increase the risk of corrosion and scaling in boilers due to its conductivity and potential to form hydrochloric acid under certain conditions. Acetic acid, while it can help in some industrial applications, is not a typical boiler treatment and may contribute to corrosion issues. Sodium bicarbonate, while it can help in regulatory pH and counter some corrosion, does not specifically target corrosion and scaling in the same effective manner as sodium sulfite does. Thus, sodium sulfite stands out as the appropriate choice for preventing corrosion and scaling in boiler water.