h3. Experimental Methods
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[!Laboratory Research Set-ups^ACD set up labeled.JPG|width=260px!|Laboratory Research Set-ups]
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The [ACD experimental set up|ACD Apparatus Fall 2008] was used to collect several data sets in Fall 2008. First the lever arm position selector was positioned at 5cm intervals along the lever arm. The lever arm was marked at 1cm intervals beforehand to allow precise selection. The water level in the grit chamber bucket was varied while readings were taken of the changing water height in the collection column.
The 7kPa pressure sensor at the base of the bucket was calibrated to read in centimeters of water and it was zeroed for the condition when the float just became buoyant and was no longer resting on the bottom of the bucket. The lever arm was made horizontal at the point by adjusting the length of fishing line tied to its end. This was checked with a level. By zeroing the pressure sensor at a lever arm height of zero all readings from the bucket pressure sensor were then equivalent to change in float height, which was also equal to negative change in lever arm end height because of the fishing line connecting the float to the end of the lever arm.
A flow control module (FCM) was connected to the chemical dosing tube at the T as is described in the [ACD experimental set up|ACD Apparatus Fall 2008]. The FCM was supplied with a bucket of water less than 1m above it at all times, ensuring that there was not significant changes in water level within the FCM. The FCM was positioned at a level with the lever arm such that it dosed no water when the lever arm was zeroed. The FCM began to dose with a change in driving head of 1mm from that zero, but this exact calibration of the set up was slightly lost in the actual experiment. I believe that headloss from the connectors entering the T may have been significant enough to slightly increase the driving head needed to get the lowest dose from the FCM into the collection column where it could be measured. The change in driving head was on the order of magnitude of a few millimeters so it probably did not severely impact the results.
To measure flowrate from the FCM through the ACD a 7kPa pressure sensor was used at the bottom of the collection column. Water flowed from the FCM through the T into the chemical dosing tube and then into the column. The pressure sensor at the base of the collection column was calibrated to read in centimeters of water, and it was zeroed with no water in the column. As water was dosed from the FCM into the column, the pressure sensor recorded both water level and time. Since the column dimensions are known, these variables can then be used to solve for a flowrate.
Concurrent data from the pressure sensor at the base of the bucket can be used to show the exact height of the float relative to the apparatus for each flowrate. Data was collected at several float heights for each distance the chemical dosing tube was attached along the lever arm or 10cm, 15cm, 20cm, and 25cm.
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h3. Experimental Results
This data has not been fully analyzed as of 10/20/08
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