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The design of th EPA scale rapid mix tube is almost exactly that developed for use in the AguaClara treatment plants, simply scaled down to provide a smaller tube and accommodate a small flow rate of water through the system. A separate MathCAD file was developed, however, to provide the full design for the EPA rapid mix tube. The flow rates of water through the tube, as well as the size and diameter of the tube itself have become mush smaller, requiring some adjustments to the original tube design. The most notable changes include: #Reduction
- Reduction in the size of the large scale mixing orifice. Because the flow rate and the tube sizes are much smaller, the large scale mixing orifice has become much smaller and occupies less of the total pipe area than in the full scale model.
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- Reduction in the size of the small scale mixing orifices. The flow rate through the system will be much smaller than originally designed for in the AguaClara plants, and thus the small scale orifices have become much smaller and occupy less of the total area of the small scale mixing plate.
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- Addition of a flow constriction at the exit of the rapid mix tube. This addition was made solely to control the flow of water through the tube to enable us to display the rapid mix tube at the EPA conference. This restriction is accomplished by adding a plate with a small orifice at the end of the rapid mix tube, which then controls the flow of water through the rest of the tube and the display system in general.
Built Model
The scale model of the rapid mix tube was constructed out of clear PVC tubing to enable easier viewing of the rapid mix process in the tube.
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