AWWA WQTC71476

Water chemistry had substantial effects on dezincification propensity in systems where brass is galvanically connected to copper. It is observed that pH, chloride, alkalinity and sulfate are all influential parameters with respect to the extent of dezincification. A pH range from 6 to 10 was tested. Both zinc and copper were leached most rapidly at low pH; however, selective leaching of zinc is highest around pH 8. Water higher in chloride or sulfate is more aggressive to brass, and the effects of chloride are more significant than sulfate. Finally, the conventional theory of "meringue" dezincification suggests that waters low in temporary hardness will have higher dezincification propensity. Results of this experiment demonstrate that low hardness, or even softened waters, is not necessarily more aggressive than un-softened waters. Rather, it appears that higher alkalinity dramatically decreases dezincification. Includes tables, figures.