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Measuring water level in high volume tanks.

Andre Mastella
Intellectual 300 points

Hi, I´m trying to measure water level in a pipe vertically mounted outside a tank that is 1.8 meter high in order to mesaure the level.

I´m using TDC1000-7200 Dev Kit with a 15mm piezo transducer.

Until now, the maximum height I got is 20 cm.

Could someone help me with information of how I can measure this 1.8 m of water column?

Thank you.

  • 0
    TI__Mastermind 21685 points
    Hi,

    For longer distance, you need higher excitation voltage or you have to hit the transducer with higher number of TX pulses or both. The TX pulse amplitude by default is 3.3V. You can get it to 5V on the TDC1000-7200EVM by changing R18 (102k) to 160k so the AVDD = 5V.
    For 1.8m, I think you also need to boost the TX amplitude to 30V or so. There's a TDC1000GASEVM that has a boost circuit built-in to do this. Please check that.

    Thanks,
    Vishy
  • 0 in reply to Vishy Viswanathan
    Intellectual 300 points
    Hi Vishy, thank you for your tips.
    I´m using a 1" diameter pipe to make tests. (This pipe will be outside the tank but with the same level of it).
    The sensor is mounted at the very bottom in the cap of this pipe.
    Do you know if this cap that is glued to the pipe is a good place to put this sensor?
    My readings even with little volume of water (from 1cm to 15 cm column) are not good.
    I´ve already changed R18 and made some experiences with number of pulses but without good results.
  • 0 in reply to Andre Mastella
    TI__Mastermind 21685 points
    Andre,

    Did you check the following app notes?

    www.ti.com/.../snaa270

    www.ti.com/.../snaa266

    Also, check this posting

    e2e.ti.com/.../467713

    Thanks,
    Vishy
  • 0 in reply to Vishy Viswanathan
    Intellectual 300 points

    Hi Vishy, thank you again.

    I´ve already read those AN.

    I´ve made some changes on the registers via GUI and the measurement is ok now.

    I noticed that without water on the pipe, it measure something about 2.5 to 3 cm and this is almost the height of the cap where the sensor is, so my previous question.

    But the system is working fine now.

    Thank you again.

    Regards

    André

  • 0 in reply to Vishy Viswanathan
    Intellectual 300 points
    Hi Vishy,
    I´ve bought a new TDC1000-BSTEVM. So I connected the old TDC1000-7200 board and the new Boost board to the sensor SMD15T21R111WL.
    The sensor is mounted outside of a cap of a tube (PVC) with 1m water column.
    Measuring with a scope at TX1 pin, I can see the pulses (4, 10 and so forth).
    If I measure at the sensor, I only see one long 30V pulse (about 30 us), but no oscillation.
    This TDC1000-BSTEVM as I could read is designed to gas metering that uses other frequencies.
    Is this the case? The amplifier does not accept the frequency generated for the sensor used?
    Or what other tests I can do?
    Is there a e-mail where I could send you the snapshots of the scope?
    Thank you.
    André

    PS: I´ve read all the AN you told me to check.
  • 0 in reply to Andre Mastella
    TI__Mastermind 21685 points
    Andre,

    If you are using TDC1000-7200EVM (red board) with the boost board, you have to remove resistors R41 and R42. Please refer to Section 2 of the GASEVM user's guide.

    thanks,
    Vishy