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TDC1000-TDC7200EVM: flow measurement with non intrusive piezoelectrics placed 45º

Matheus Costa
Prodigy 80 points

Part Number: TDC1000-TDC7200EVM

I want to make a flow measurement placing the sensors like the Z-mount shown in the picture but as far as now I did not have success. With that I'm wondering if there is any limitation to do that with the TDC100-TDC7200EVM board, or maybe have problems with my experimental setup, where I just glued the sensor in a 45° angle direct on the pipe.

  • 0
    TI__Genius 11015 points
    Matheus,

    Per your application the Z mount configuration should be very much doable.
    Also recommend you see the application notes on water flow metering using the TDC1000 as in the document below:

    www.ti.com/.../snia020.pdf


    We recommend the MSP430 based ultrasonic sensor for flow metering purpose for better accuracy and resolution.
    www.ti.com/.../MSP-ULTRASONIC-DESIGN-CENTER
  • 0 in reply to Bharat Aravamudhan
    Prodigy 80 points

    Thanks Bharat for the answer,


    So I did some tests today and the data readed in the TDC1000-TDC7200 GUI are showed in the first 3 pictures showed below and do not seems right. I used the configuration showed in the fourth picture.


    The first picture below shows the actual flow rade measured in the eletromagnetic flow meater and the second the expect Delta TOF for the configuration to my sensor.


    I made the same test placing the sensor in de z-mode and the results seems the same. Do you have any idea what can be hapening in my tests? Like maybe I'm doing something wrong in the gluing sensors process or in the configuration of my TDC1000-TDC7200EVM board?

  • 0 in reply to Matheus Costa
    TI__Genius 11015 points

    Matheus,

    Please let me know if the transducer is inside the tube or not. Also please get the Time of Flight without the liquid flow and see if the ToF gives the actual distance between the 2 transducers.

    Also try to increase the Num Avg and see if you get any stable reading.

  • 0 in reply to Bharat Aravamudhan
    Prodigy 80 points

    Bharat,
    The sensor is placed in the outside of the tube, the pictures below show how.


    It considered the mean velocity between the fraction of steel and the fraction of water the TOF is what have to be, considering the actual distance betwen the sensors, but withowt water the value shown is the same.


    Increasing the Num Avg the reading is a litle bit more stable, but continues very wrong.

  • 0 in reply to Matheus Costa
    TI__Genius 11015 points

    Matheus,

    Placing the transducer outside the metal tube can hamper the accuracy of the ToF readings.

    The Tx pulses from A transducer might not be strong enough for B transducer to receive and respond. I would recommend placing the transducers inside the pipe in a straight line of sight.

  • 0 in reply to Bharat Aravamudhan
    Prodigy 80 points

    Bharat,

    I see, but in my case it's not possible to place the transducer inside the pipe. Do you have any other tips to solve this problem? If I make a circuit to increase the Tx pulse might be possible to do this reading?

  • 0 in reply to Matheus Costa
    TI__Genius 11015 points

    Matheus,

    You could try and drive the transducer with higher voltage and see if the signal is transmitted and received. 

    In ultrasonic the sound typically reflected even at the wall of the metal pipe and it is pretty tough to get the Tx signals though the pipe.

    The best solution would be to have the setup as shown in the Application note in the link below for flow metering.

    http://www.ti.com/lit/an/snia020/snia020.pdf