Abstract
The addition of certain metallic cations in very small quantities to synergized polyphosphate treatments in cooling tower systems will increase corrosion protection. This new approach is considered in detail with accompanying laboratory and field data. Data given include a comparison of corrosion inhibition by the polyphosphate and synergized inhibitors, effect of Zn, Gd, Cu and Sb ions on corrosion inhibition by synergized polyphosphates, and effect of metal dosage level. It was found that overdosing of the metal in some cases may remove any beneficial effects and may actually result in harm in some cases.
The theoretical reasons for the effect of metal cations have yet to be established. It is likely, however, that cathodic inhibitors such as zinc may help prevent the formation of local cells at points on the metal surfaces where potential differences exist. 5.8.2
