In open cooling towers, how do corrosion inhibitors help?

• A. They form protective films and scavenge corrosive species
• B. They dissolve metals to remove corrosion
• C. They convert metal to a different alloy
• D. They raise the water temperature

Answer: (A)

In open cooling towers, corrosion inhibitors work by two complementary actions that reduce the metal’s exposure to the corrosive water. First, they form protective films on the metal surface, creating an adsorbed barrier that slows or blocks the electrochemical reactions responsible for corrosion. Second, they scavenge or neutralize aggressive species in the water—such as dissolved oxygen, carbon dioxide, and other ions—that drive corrosive processes. By both shielding the surface and removing the things that hasten corrosion, the overall corrosion rate is reduced. The other options describe effects that inhibitors don’t perform, such as dissolving metals, changing the metal itself, or altering temperature, which don’t address the corrosion mechanisms in open towers.