Detecting water flow in pipe with Ultrasonic Motion Detector

Discussion in 'The Projects Forum' started by alex04032, Aug 12, 2009.

  1. alex04032

    Thread Starter New Member

    Aug 12, 2009
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    0
    Im trying to detect when water stops flowing in a 1" iron pipe.... from the outside of the pipe. I see ultrasonic flow meters on-line, they look like Doppler effect instruments, but they are very expensive. So Im thinking to modify an off-the-shelf home security device for the job.

    To start, Im thinking to put the transmitting ultrasonic device on the pipe, then put the receiving device some length away along the pipe.

    Any input/ideas how to approach this and what to watch out for are greatly appreciated !

    If you think sensing for lack of sound using a piezo transducer would work better, I want to hear your ideas on that, too.

    Thank you !
     
  2. ELECTRONERD

    Senior Member

    May 26, 2009
    1,146
    16
    You could just have a little propellor in the pipe that connects to a small generator. When water flows a small amount of electricity will be generated which you can detect with a voltmeter. If there is no water flowing, the propellor won't turn and therefore neither will the shaft of the generator. Thus, you have no electricity.
     
  3. jj_alukkas

    Well-Known Member

    Jan 8, 2009
    751
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    Why go for ultrasonic when there are cheaper alternatives? 2 wires in the pipe to a 2 transistor astable multivibrator will indicate water IF AND ONLY IF water doesnt stay in the pipe after pumping. If its a ground pipe, then water will stay always, so a vibration detector or a tiny generator as suggested above or an IR Tx-Rx will do.

    If it is ultrasonic you need, modify the attachment ckt. And yes, you can use a piezo transducer, provided, you dont keep the waves just bouncing in the pipe and get false triggers.
     
  4. alex04032

    Thread Starter New Member

    Aug 12, 2009
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    Yes, using a mechanical flow switch would be totally simple, but would require hiring a plumber and "cutting it in". Simple water detection via conductance also requires taking the pipes apart, but in this case the water is always present, never goes dry... just flowing or not flowing. This is the domestic water main to apartment building.
     
  5. jj_alukkas

    Well-Known Member

    Jan 8, 2009
    751
    5
    Well then how are you gonna get those transducers in there??
     
  6. alex04032

    Thread Starter New Member

    Aug 12, 2009
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  7. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,696
    904
    Have you considered heating tape and a thermistor? When the water is still, you will reach one steady state. When the water is moving, the steady state should be lower, or at least different. Probably can't measure flow too well that way, but you could tell on from off.

    John
     
  8. alex04032

    Thread Starter New Member

    Aug 12, 2009
    4
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    That's an interesting approach, John. I will think on it.
     
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