 Tech Talk
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Ask Don!
USABlueBook
Technical Training Manager |
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| Sodium Hypochlorite (Keeping the Potency) |
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| Many systems use sodium hypochlorite as their source of chlorine. We often hear about how it degrades over time, and little on how to minimize that degradation. Here are some factors that affect chlorine’s ability to maintain its strength. |
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| pH is the single largest factor that affects chlorine’s stability. |
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| When pH drops, chlorine takes the form of hypochlorous acid, which is much more prone to react and is less stable. It is no wonder that when sodium hypochlorite is shipped, it typically has a pH greater than 11. |
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| Frequently the day tanks in which we store chlorine before injecting have a pH of 6 to 8, resulting in a significant loss of chlorine potency in two to three weeks. |
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| Increasing the pH of the solution to 10+ by adding caustic soda or soda ash will increase the solution life nearly 50%. This does not affect the finished water pH because of the very small amount of chlorine injected from the day tank. |
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| Temperature and sunlight are the next major factors affecting potency. |
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| High temperatures cause the chlorine to dissipate from the solution. Of course the higher the temperature, the more dissipation occurs. |
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| Ultra Violet rays (UV) from sunlight also play a factor. UV at specific wavelengths (180 to 200 nm) has been shown to be an effective dechlorination method. Storage in a cool dark room is ideal; however, depending on location, a black storage tank may suffice. |
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| For more information, please contact Don at 503-544-0456 or dvanveldhuizen@usabluebook.com or LoAnn Mayer at 847-377-5162 or lmayer@usabluebook.com. |
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