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Water Pressure sensor

  1. Aug 15, 2011 #1
    I have a water tank, and i want to make a circuit that measures the water height, and display the value on a 3 seven segment display as a percentage of the total height.

    So am searching for a pressure sensor that i want to put in the tank.

    Can any one advise me for a sensor number that i may use for such application.

    I search on google, and i found many types of pressure sensors but i don't know which one i should use for my application.

  2. jcsd
  3. Aug 16, 2011 #2


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    Something like this?

    http://www.omega.com/prodinfo/pressuretransducers.html" [Broken]
    Last edited by a moderator: May 5, 2017
  4. Aug 16, 2011 #3
    I don't think this will fit the application, since the sensor should be immersed in water( at the bottom of water tank).

    I think i need something like the sensor that measures the level of benzene in cars.
  5. Aug 17, 2011 #4
    Can't you just use a scale? You have a known volume (the tank) and water is 1kg per liter. Okay, so 1kg per liter probably isn't totally accurate but it's pretty close and probably going to have about the same precision as what you're proposing. Anyway, you could always account for that by recalculating how much 1L of water weighs by measuring the ambient temperature and pressure.

    That's one way to do it...
  6. Aug 17, 2011 #5


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    A water tank will normally have a pipe outlet near the bottom and the pressure in this pipe will be the same as at the bottom of the tank when no water is flowing.
    So this would be a convenient place to put a pressure sensor. You then don't have to have electric cables immersed in water.

    Another approach is to have a small compressor and blow air down a pipe in the tank until bubbles come out of the end of the pipe near the bottom of the tank. The air pressure needed to do this will depend on the depth of water in the tank.
    You only need to do this when a reading is being taken.
    This also avoids having electric cables immersed in water, which is always a high maintenance problem.

    The fuel gauge in a car is operated by a float rotating a potentiometer. You can do something similar by having a float rise with water level and rotate a pulley which turns a potentiometer.
    You can get 10 turn potentiometers, so you could work out the pulley diameter depending on the depth of your tank.
    If the tank was 2 M deep, each turn of the pot would need 20 cm of pulley circumferance so the pulley would have a diameter of 6.3 cm or 2.5 inches.
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