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- Chlorine dosing is accomplished with 70% Calcium Hyper ChloriteHypochlorite. A 5 pound bag is mixed with water in a 55 gallon drum. This gives a chlorine concentration of 7.625 grams / Liter.
- 55 pound bags of alum are mixed with water in a 55 gallon drum providing a concentration of 120 grams / Liter.
- The CDC should be able to maintain an alum concentration of 10 to 80 mg/L in the plant. The low and high end of this scale can be manipulated slightly in order to create a uniform scale. For example, the triple-scale uses a range of 8 - 88 mg/L.
- The CDC should be functional and accurate down to a plant flow of 50%.
- 5% variance between fabricated orifices is the current goal.
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Orifice Validation and Scale Development Development (2 - 4 Persons)
One of the priorities of AguaClara engineers is to ensure their designs are locally sustainable. It is easy to create the walls and foundations from locally manufactured materials but becomes increasingly difficult when very specific components are needed to perform very specific tasks. This proved true with the float valve used in the constant-head tank and may prove true with a metering orifice. The team that originally developed the NDC was not able to fabricate precise (e.g. repeatable) orifices for their lab tests. This team also noted that surface tension effected accuracy of a metering orifice when less than 4 cm of head was available. The Summer 2010 team concentrated on documenting the extent of the precision problem and researched various solutions. It is the belief of the Summer 2010 team that we can not properly quantify the inaccuracies associated with surface tension until the material and manufacturing techniques are finalized since material finish, or smoothness, has a strong influence on surface tension.
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The current float valve is manufactured by Kerick Valve Inc. The MA2P2 or MA3P2 are both used in our plants and both have an internal orifice diameter of .093" (2.36 mm). The flow rate through the valve is limited by this orifice and as plant's increase in size, the valve will not be able to maintain the correct proper level in the CH Tank. In fact, two CH Tanks are installed in parallel at Marcala, one of our larger plants, to accommodate this issue.
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