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The Linear Orifice Flow Meter was tested and compared to the results expcted from a traditional sutro wier. The steps of the experiment and th the results are available below. The experiment showed a very low deviation from the predicted. It in important to note that the design for calculating the orifice pattern used the old design and the first two rows are not designed optimally.
Initial Design
Figure 1: Rough Schematic of existing structure
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Since the existing PVC pipe that brings the water in is 3" I will use the 3" pipe to construct the riser pipe. Checking with the program the 3" will be more than big enough to accomodate the holes. the holes necessary for the riser pipe were found using the mathcad program developed by David Railsback for linear flow. After Talking with Tom at the water treatment plant I think i will decided to use a 5 gallon bucket. It would be relatively easy to outfit the bucket with a toilet flange on the bottom of the bucket that the riser pipe can slide into. My earlier worries about the size of the entrance tank were unfounded because it turns out that the area of the entrance tank doesn't matter only the height of the tank.
Figure 4: A close up view of the riser pipe with the necessary holes. As a note the diameter of the holes is 3/8 inches. The tube on the left is designed with a max flow rate of 120 L/min and the pipe on the right has a max flow rate of 125 L/min
Figure 5: Actual photograph Photograph of the riser pipe
Budget
Item | Amount Necessary | Price |
|---|---|---|
5 gallon pale, transparent | 1 | $5 |
3" PVC Pipe | 4.1' | $16.64 for 8' |
toilet flange | 1 | $3 |
stainledd steel screw | 4 | $2.00 |
Bracing | Not sure | Tom willing to help and provide materials |
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#I decided to cut the holes on the pipe for a maximum flow of 125 L/min (the actual max is 120 L/min) so that there would be some wiggle roomextra capacity.
#An extra piece of tubing was used underneath the bucket to add extra length and mitigate the spashing and spilling that originally occured.
Note: I have stopped by several times over the past couple of weeks to work with tom to help install the bucket and the flow control device and it seems to be taking much longer than i had originally anticipated. The Bucket is comletely The Bucket was completely installed on March 13th.
Figure 6: close up of completed bucket
Figure 7: Completed bucket installed in pilot plant
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The entrance tank with riser pipe was installed in the plant and measurements were taken on the efficiency and accuracy of the design. There is was an in-line flow meter that will provide provided flow rate data that can be compared to the flow rate recorded based on height in the entrance tank. There will be readings at incremental flow rates where the machine flow rate and water height will be recorded.
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- Record the water height for flows between 5 and 36 GPM in approximately 1 GPM increments
- The flow meter has an accuracy of +/- 0.25% of the flow rate. The flow meter is made of two parts and produced by siemens.
Figure 1: The sensor with display is pictured above and the model is SITRANS F M MAG 3100, statistics specifications for the sensor are available at the Seimens website.
Figure 2: The microprocessor-based transmitter that displays the data is pictured above and the model is SITRANS F M MAG 6000, statistics specifications are available at the siemens website.
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Figure 2: The graph shows the flow rate versus height data for the three experimental trials and the predicted data.The original graph is availabl here
- The experimental data from the three trials have high similarity to one anotherare similar. This shows consistency in the experimental set-up.
- There is some discrepency between the predicted values and the experimental values.
Figure 3:The graph below show the differnce between the predicted height and the recorded height as a function of water heightflow rate.The original graph is available here
Figure 4: The graph below show the percent deviation between the predicted height and the recorded height as a function of water height. The equation used to create the data is 
.The original graph is available here
Possible Causes of Discrepency
1. There is a significant error at the low flow rates. It is possible that this error was due to the faulty algorithm used to design the LFOM. Note that the first code did not design the first 2 rows of the LFOM well.
2. Accuracy of the flow meter installed in-line at the pilot plant. The readings may be inaccurate.
- Research into the flow meter specifications showed guaranteed accuracy up to 0.25% of the flow rate.
- Data taken manually to determine actual flow compared to the flow meter is not significantly from the flwo meter to suggest problems with the flow meter.
Flow Meter Reading, GPM
Actual Flow Rate, GPM
% Deviation
4.6
4.69
1.97
6.1
6.25
2.51
7.4
7.53
1.85
11.1
11.62
4.71
- Flow meter accuracy not the problem.
23. Problems with the orifice equation approximating the head loss on a vertical orifice, the equation was designed for a horizontal orifice. May need to integrate to find the head on the holes as a function of height, would lead to changes in construction of the riser pipe.
3 4. The percent deviation graph show a constant percent deviation as the flow rate increases of about 10% after an initial spike due to the effect of small errors on small value readings. The errors seen at the upper limits aren't extreme, they are consistent with the other deviations.
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