Experimental Background
The deep bucket being used for the virtual grit chamber in the float height versus chemical dosing experiment was not deep enough to allow testing of the full 20cm range of dosing motion.
Experimental Methods
To test the full range of motion of the CD efficiently the experiment was modified so that the lever arm was held in place by a ringstand and clamp. The ringstand was marked with a centimeter scale with zero being marked where the clamp help the lever arm such that no liquid came out the pressure break T, but any lower clamp position caused flow to occur.
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By securing the lever arm at precise heights, an exact float height could be simulated. The rest of the experimental method remained the same from the outflow to float height experiment. Namely, the chemical dosing tube was positioned at 5 cm intervals along the lever arm while outflow was measured by the pressure sensor in the base of the collection column. Data from the sensor was recorded in centimeters of water by using the Easy Data software.
The lever arm was positioned at heights of 5 cm, 10 cm, 15 cm, and 19 cm, and the doser was positioned at a distance from the pivot of 5 cm, 10 cm, 15 cm, 20 cm, 25 cm, and 30 cm. Data was collected at every combination of those parameters, producing 24 flow rate data points.
Results
The results for this experiment show data that is mostly consistent with theoretical projections. The data sets for each distance away from the pivot show a clear linear trend, with the slope increasing by a constant factor with each 5 cm increment of distance added. When projected leftward, the data all approaches the origin. The only unexpected data point is at (19, 1.777) in the 30 cm data set.
Similarly to data collected with the lab prototype and the robust CD with the float attached, the system appears to be less responsive when used farther away from the pivot. The graph below replaces data points with lines, which shows this trend more clearly. The lines of data further from the pivot (20 cm, 25 cm, 30 cm) are closer together than the lines representing data close in to the pivot (5 cm, 10 cm, 15 cm).
This inconsistency is relatively small, though, and indicates that the robust design of the CD may be capable of dosing relatively precise amounts of fluid.