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During the fall semester of 2009, the Non-linear Chemical Alum Doser Team calculated the two orifice sizes and developed the dual scale for the lever arm. Our goal was to meet the alum needs of the upcoming AGALTECA plant, which has a maximum flow rate of 6.3 L/s, maximum alum stock dosage of 125 gm/L, and a maximum target alum target rate of 100 mg/L. We determined that a nonlinear alum doser with a scale arm length of 0.5m, total lever length of .75m, tube diameter of 3/8 inch, and orifice sizing of .082 inch and .044 inch can meet the needs of the AGALTECA Plant. Other lever arm parameters can be found along with the calculations deriving them on the embedded 2009 NCDC Lever Arm Calculations: 2009 NCDC Lever Arm Calculations.xmcd Mathcad file.
Methods:
Our method consisted of 1)establishing the relationship between plant flow rate, alum dosage, delta h between the constant head pump, and the dual scale 2)utilization of Mathcad Array function to link them 3)Trial and Error process to determine orifice size and the dual arm scale.
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