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Water level measurement how?

  1. Feb 17, 2009 #1
    I want to measure level of water at two positions in tank. How to measure it?

    |-----|_> here &
    | ----|_ >here
    Fig. Tank

    when water level reach to certain levels(1,2) o/p voltage should be generated. I hav to connect it to 24 V DC PLC i/p.

    I need simple and easy solution.
    PLZ help me.
    Last edited: Feb 17, 2009
  2. jcsd
  3. Feb 17, 2009 #2


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    Use a float switch.

  4. Feb 17, 2009 #3
    thanx for reply. I havn't seen a float switch before. How does it work?

    this is what the prob. is
    there are three tanks 1,2,3
    water from tank 1 and 2 come in tank 3
    i want water from tank 1 should be shut off(i. e. o/p signal should be genrated which will be given to valve of tank 1) after reaching certain level in tank 3.
    Same thing for tank 2.

    Will this ckt shown work for me?

    http://img88.imageshack.us/img88/366/watermx3.th.jpg [Broken]

    I found on this

    if yes then plz expain how
    Last edited by a moderator: May 4, 2017
  5. Feb 17, 2009 #4


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    Homework Helper

    Float switches are just like the float that turns off the water filling your toilet. they either have a mercury tilt switch inside or more likely these days an accelerometer. The gas level gauge in your car is similair.
    The connection is on at some angle and off at an other - you just adjust how it is mounted to turn on/off at the desired level.

    The trouble with the bare wires conduction sensor discussed in the other thread is that they are vunerable to the electrodes corroding or getting covered in some insulating gunk in an industrial process. Float switches are sealed and a lot more reliable

    Lots of plumbing supply places sell float switches, they are used to run sump pumps.
  6. Feb 17, 2009 #5
    I hav to measure level of water at two positions.
    for first position Float switch will do it.
    But what abt 2nd position?

    tank 1 tank 2
    |-----| |-----|
    | ----| | ----|
    |____| |____|

    | |
    |-----|_> pos. 2
    | ----|_ > pos. 1
    tank 3

    the water from tank 1 going in tank 3 can shut off by using one Float switch but what abt water coming from tank 2 going in tank 3?
    Last edited: Feb 17, 2009
  7. Feb 17, 2009 #6


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    You can either have a float with an analogue output (like a gas tank gauge) and detect two outputs with some extra circuitry.
    Or you can have two float switches set for different levels = easiest.
    Or somebody might make a float switch that sets two different outputs at two different levels (I don't know of one).
  8. Feb 17, 2009 #7
    You could a Liquiphant level switch, depending on what you want the swithc to do it will send a 24v signal through the switch wire to a relay,PLC o whatever you have set up.

    The Liquiphant has basically two paddle/prong arrangements that vibrate at a certain frequency, as soon as they are submerged by a liquid the change in vibration frequency is detected and a signal is made which can be wired into anything.

    I'd use two of those sensors
  9. Feb 17, 2009 #8
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