Outlet flow measurement of a mount-top drinking water treatment plant

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Dear friends,

A mount-top water treatment plant has DN700 steel outlet pipe with EMF(electro-magnetic flow meter). Due to the gravity flow, this DN700 outlet pipe is not full of water sometimes. And then, the EMF is not available to measure the outlet water in good accuracy.

In order for EMF to improve measurement accuracy, we want to re-install or renewal this DN700 steel outlet pipe. What are your advices to measure the water flow in gravity pipe?

 Thank you a lot in advance.

 

Best regards,

 

Wu Hao 

 

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5 Answers

  1. Once  the system uses gravity to work, i think the easiest and most economical way will be to raise the outlet above the flowmeter level so whenever there is flow it is guaranteed that the flowmeter is completely filled with water ( like the picture that Mr. Reyhan presented)

    Good luck

    Best regards

    jose rafael

  2. Hi Wu Hao, the flow meter can be reinstalled so it always runs full by installing the main pipe vertically downwards then horizontally with the meter in the horizontal section before placing a rising section to return to the existing pipe alignment.  The vertical pipe section allows air to rise against the flow direction and be released in the reservoir. At the point downstream of the meter where the pipe rises and returns to the existing pipe a vent pipe should be installed and run to up to the overflow level of the reservoir (perhaps attaching it to the side of the reservoir).  This will release air trapped in the pipeline downstream of the meter.    It is not usually possible to use an air release valve at this point as the pressure is low and ordinary air valves will leak.

    2 Comments

  3. Hi. I think the pump in the domain of the hill should be checked first if there is one. maybe the efficiency or calculation has some issues. Then you may use a mechanical flow switch to signal the ultrasonic meter to work otherwise signal low flow/pressure to the control system to be checked or start a pump.

    flow switch picture:

    flow switch.jpg

    or you can use multiple elbows to make the flow efficiency better. Check the attached PDF. If you need more help please contact me on:

    alireza.reyhan@gmail.com

    Good luck

     

  5. Check out this Circular

     

    file:///C:/My%20Files/DESIGN/Pipes/Flow%20measurement.pdf

     

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