Polyphosphate surface active agents

Offline passivation involves treatment of equipment currently out of service. Treatment levels are typically higher consequently, passivation is completed more quickly. Passivation of nonchromate treatment generally uses either a polyphosphate, zinc, molybdate or other nonchromate-based inhibitor in combination with various surface-active cleaning agents. The passivation solution should be disposed of after the pretreatment stage, rather than dumped back into the cooling system where the potential for fouling can exist due to the precipitation of pretreatment compounds such as zinc or phosphate. Table 8.1 outlines both online and offline pretreatment procedures. 

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