The most common treatment to protect copper and copper alloys in a cooling system is?

The treatment that is most commonly used to protect copper and copper alloys in cooling systems is azoles. Azoles are a class of organic compounds that are effective in minimizing corrosion, particularly in systems where copper is present. These compounds function by forming a protective film on the surface of the metal, significantly reducing the rate of corrosion.

Azoles are particularly favored in cooling water treatment because they can provide a dual benefit: they inhibit corrosion and can also offer some level of biofouling control. This makes them an efficient choice for maintaining the integrity of cooling systems with copper components.

While other options like orthophosphate with zinc and molybdate are also used in corrosion control, they may not specifically target copper as effectively as azoles. Phosphonates are utilized in various applications for scale control and corrosion inhibition but often do not provide the targeted protection for copper and its alloys like azoles do. Therefore, when it comes to the common practice of protecting copper and copper alloys in cooling systems, azoles stand out as the preferred treatment option.