Galvanic corrosion is caused by the electrical contact between dissimilar metals in a fluid stream. It is therefore very important not no use different materials for the collector construction and piping manifolds. For example, if copper is used for the construction of the collector, the supply and return piping should also be made from copper. Where different metals must be used, dielectric unions between dissimilar metals must be used to prevent electrical contact. Of the possible metals used to construct collectors, aluminum is the most sensitive to galvanic corrosion, because of its position in the galvanic series. This series, shown in Table 5.5, indicates the relative activity of one metal against another. Metals closer to the anodic end of the series tend to corrode when placed in electrical contact with another metal that is closer to the cathodic end of the series in a solution that conducts electricity, such as water.
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