Name common corrosion inhibitors for open cooling towers.

• A. Phosphates, nitrite-based inhibitors, molybdate/phosphate blends, silicates, and biocide considerations
• B. Chlorine gas
• C. Zinc plating
• D. Pure water

Answer: (A)

Corrosion control in open cooling towers relies on inhibitors added to the circulating water to form protective films and slow metal deterioration in a harsh, warm, chloride-rich environment. The common inhibitors used are phosphates, nitrite-based inhibitors, and blends such as molybdate/phosphate, with silicates often employed as an additional barrier film. Managing biocides is also part of the strategy because microbial activity can influence corrosion through microbiologically influenced corrosion, so biocide considerations are integrated into the inhibitor program. Other options don’t fit this purpose: chlorine gas is a disinfectant rather than a corrosion inhibitor and can even promote corrosion under certain conditions; zinc plating is a surface coating rather than a water-chemistry corrosion inhibitor; pure water provides little to no protection and can be corrosive if not properly buffered.