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Ultrasonic water level sensor

Discussion in 'Hobby Electronics' started by Russ, Dec 29, 2003.

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  1. Russ

    Russ Guest

    I remember seeing a circuit for a water level sensor for tanks that used a
    pair of ultrasonic transducers atop a length of PVC pipe in SC or EA,
    however for all my hunting I can't seem to find any reference to it. Does
    anyone know in which issue the article appeared, or of a similar design that
    I could use?

  2. Derek Weston

    Derek Weston Guest
  3. Derek Weston

    Derek Weston Guest

  4. Hello Dereck,
    decades ago I saw a device that was made by Adelaide
    University that measured wave or swell heights.

    I am a bit hazy as to the exact workings of the device.
    Visualise a small piece of pipe several inches in diameter
    and several inches long with flanges at both ends with
    lots of holes around the flange ring. The sort of pipe
    fitting you would see laying around at an oil refinery
    or in a boiler makers shop.

    Inside the pipe is an audio oscillator.
    One end of the pipe was made of some sort of hard
    rubber or hard plastic type material. I can't remember.
    This hard rubber material worked like your ear drum.
    As the pressure on it increased it moved in microscopically.
    Attached on the inside was some sort of gearing and levers
    that you find in bourdon tube pressure gauges. I am hazy,
    I can't remember how the movement of the drum changed
    the frequency of the oscillator, a pot or capacitor, I can't
    remember. Anyway this pipe assembly was sealed up
    with a heavy brass end plate with wires coming out of
    a heavy duty gland. It was placed in a pressure chamber
    and the frequency of the oscillator was recorded for various
    increments of pressure. A calibration chart was drawn up
    frequency versus pressure. The boffins new already that
    a certain head of water represents a certain pressure.

    So with this transducer laying on the seabead near the
    beach or jetty with a frequency meter attached via long
    cables, the wave peaks and troughs could be read as
    frequency readout.
    The calibration chart can then be looked up to give height
    of peak and height of trough above the sea bed.

    Sorry for being so long winded.
    John Crighton
  5. cdb

    cdb Guest

    How about just using a pressure transducer similar to those in washing

    I'm just assuming here that, as a wave fills a container (tube) of some sort
    from the bottom, a pressure is created that could be analysed to give hight
    of wave information.

  6. Derek Weston

    Derek Weston Guest


    Thanks for your comments gentlemen.

    There are systems which use submerged pressure transmitters, bubble
    tubes and above-the-water pressure transducers, upward-looking
    ultrasonics (upside down depth sounders), and capacitance and resistance
    measurements between immersed probes. I'd like to avoid immersed
    sensors, as they become fouled by marine growth in short order if
    unprotected, and when coated with antifouling paint they are generally
    significantly fouled within a year.

    The most reliable above water sensor used for the task seems to be
    radar, but the cost is high. Industrial sensor suppliers I've contacted
    regarding using ultrasonic ranging and optical ranging don't recomend
    their sensors for exposed marine environments where they'd be subject to
    salt spray and occassional green water, and/or don't think they'd
    reliably "see" the wave profile because of its shape scattering the
    light or ultrasound.
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