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    Free hydrogen ions found in all water to at least some extent provide a means of removing the excess electrons from the mass of metal. The electrons and the hydrogen ions react to first form atomic hydrogen, and then molecular hydrogen gas. As the hydrogen forms, it too tends to inhibit further corrosion by forming a very thin gaseous film at the surface of the metal. This “polarizing” film can be effective in reducing water to metal contact and thus in reducing corrosion. Yet it is clear that anything which breaks down this barrier film tends to increase the rate of corrosion.

    Dissolved oxygen in the water will react with the hydrogen, converting it to water, and destroying the film. High water velocities tend to sweep the film away, exposing fresh metal to the water. Similarly, solid particles in the water can brush the hydrogen film from the metal.

    Water temperatures. High water temperatures not only accelerate the chemical reactions of corrosion, but also may reverse normally protective systems.

    The removal of hardness with an ion exchange water softener does not affect the factors, which cause or accelerate corrosion. Softening does not change the pH or carbon dioxide concentration, the dissolved oxygen concentration, or the total chemical concentration of minerals. A softener may reduce the amounts of solid particles in the water, but obviously cannot change other physical factors such as temperature, flow rates through pipes, or volumes of water used. Thus ion exchange softening neither causes nor controls corrosion.

    Respectfully David F. Walling

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