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EVM430-FR6043: Water Meter Constant and Calibration

Hugo Luís
Prodigy 20 points
Part Number: EVM430-FR6043


Hello, after reading some of the documentation for the EVM430-FR6043 it is not clear why it is needed the Meter Constant. (I am assigning each question a number for an easier reply)

From my understanding I need to use the Meter Constant if my application only requires to measure flow around a given value (and no calibration is needed). However, if my application needs to measure the flow rate in a given range, I will need to calibrate the sensor, while the Meter Constant is irrelevant and I do not need to calculate it. (1) Is this correct?

For context, my application will need to measure from around 0LPH to higher values such as 600LPH or more, so it is not around a single value. (2) So, can I ignore the Meter Constant and only perform the sensor calibration or I need to calculate the Meter Constant as well? (3) If so, which value from the range should I chose for calculating the Meter Constant?

I also have another question. Regarding the formula for measuring the Volume Flow Rate, after reading the Webinar slides and also the TIDM-02005 Design Guide it is not clear how, in practice, the algorithm does not need the pipe area nor the distance between the two transducers. From my understanding, the algorithm uses the formula on the 10th slide to calculate the Q (Volume Flow Rate), I attached a figure below with the formula. However, when running the Water Demo Code I do not need to input the pipe area neither the distance between the two transducers, thus, is not using such information to calculate the VFR. (4) How can the algorithm calculate the VFR with only the DTOF and absToF? (5) Is this related with both the calibration process and the Meter Constant?  (6) By calibrating the sensor or calculating the Meter Constant are we actually calculating the Area empirically?

Thank you,

Hugo Luís

  • 0
    TI__Mastermind 29105 points

    Hello Hugo,

    I'm not sure if you've seen it, but we also have a Water Metering MSP Academy.  This training provides a water flow measurement overview and walks through the process for performing all the testing needing to be done with a specific transducer/pipe configuration.  

    Please take a look and let me know if this can address most of your questions. 

    Thanks,

    JD

  • 0 in reply to JD Crutchfield
    Prodigy 20 points

    Hello JD,

    Thank you for your reply. I read that document that you recommended but I'm still not sure if I understood it correctly.

    I need to calculate the Meter Constant regardless of the application. So, the procedure should be: (1) calculate the Meter Constant by having a constant flow rate and by varying the Meter Constant until the Device Under Test (DUT) matches the Volume Flow Rate measured by the reference meter, (2) calibrate the DUT using multiple ranges?

    The second, more theoretical question, is not answered, or at least directly answered, in the document you recommended. Could you elaborate why I do not need to tell the algorithm the distance between one transducer and another? (My transducers are arranged in a reflective configuration)

    Thank you,

    Hugo Luís

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