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The Linear Orifice Flow Meter was tested and compared to the results expcted expected from a traditional sutro wierweir. The steps of the experiment and the results are available below. The experiment showed a very low deviation from the predicted. It in is important to note that the design for calculating the orifice pattern used the old design and the first two rows are not designed optimally.
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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 accommodate the holes. The holes necessary for the riser pipe were found using the mathcad Mathcad program developed by David Railsback for linear flow. Talking with Tom at the water treatment plant I 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.
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Item | Amount Necessary | Price |
|---|---|---|
5 gallon pale, transparent | 1 | $5 |
3" PVC Pipe | 4.1' | $16.64 for 8' |
toilet flange | 1 | $3 |
stainledd stainless 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 extra capacity.
#An extra piece of tubing was used underneath the bucket to add extra length and mitigate the spashing splashing and spilling that originally occuredoccurred.
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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- 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 siemensSiemens.
Figure 1: The sensor with display is pictured above and the model is SITRANS F M MAG 3100, 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, specifications are available at the siemens website.
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- The data collected from three trails is available as an excel document.
- There is a correction factor for the water heights because the first hole isn't at the bottom of the bucket. There is an offset of 3.5 inches. Also the lengthy decimals result from using english English units with eights and sixteenths inches.
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- The data from the three trials are similar. This shows consistency in the experimental set-up.
- There is some discrepency discrepancy between the predicted values and the experimental values.
Figure 3:The graph below show the differnce difference between the predicted height and the recorded height as a function of flow 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
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Discrepancy
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 flow 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.
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The design for a flow measurement device was tested. A riser pipe with a pattern of holes was used to restrict the flow so the height of water in the entrance tank of a water treatment plant directly correlates to the flwo flow through the riser pipe. Three trials were undertaken to determine if the system of holes reliably and accurately approximates a sutro wierweir. As long as a system can be devised to prevent the clogging of holes during operation the riser pipe is an effective tool. The riser pipe entrance tank sytem system provides data on flow with an accuracy of approximately ten percent.