General considerations involved in reducing corrosion by the several types of cooling water systems are discussed. The objective of treatment is to form a coating protective against corrosion but not too thick to seriously affect efficiency of heat exchange surfaces. Treatments include pH control, addition of anti-biologicals, insulation to stop stray current corrosion, oxygen removal.
Information on laboratory research on inhibitors by the Drew Company is given. Addition of chromates in correct concentrations stopped corrosion but insufficient amounts caused pitting. Silicate-phosphates gave better results. Mechanism of silica-base inhibitors is discussed. Conclusions reached include the controlled calcium carbonate method requires too close control, chromates are effective in proper concentration but relatively expensive unless small volumes of water are involved. Erratic results were obtained with systems involving complex phosphates at pH 6.0 and chromatephosphate combinations. Good results were obtained with silicate-phosphate combinations.
