Public Lab Research note

Depth Sensor Proposal

by danbeavers | May 18, 2016 18:20 18 May 18:20 | #13126 | #13126

What I want to do

I am proposing this sensor as an inexpensive method to measure water depth. This device has not been constructed but I hope that interested parties will experiment with this design and report their results in the comments section below.

System Illustration for phase 1



After constructing the system it will need to be adjusted to the range of expected variation. In order to do this both the needle valve and the amount of water in the manometer will need to be adjusted. Having too little water in the manometer will be a problem causing it to exit into the rest of the tubing. A large manometer will be advantageous and will not reduce accuracy significantly.

  1. Determine the range of the height variation that you wish to measure and provide a method to experiment with this range. A clear vertical tube filled with water of sufficient depth would be ideal.
  2. Place the open end of the measuring tube at the maximum depth.
  3. Observe that bubbles are escaping from the tube. If they are not then open the needle valve until there is some air escaping. The amount of bubbles does not need to be large there just have to be bubbles escaping.
  4. The manometer should be displaying the maximum pressure.
  5. Move the open end of the measuring tube to the minimum depth you expect to measure.
  6. The tube should still be producing bubbles and the manometer should be displaying a lesser pressure.

Now that the system range has been set the accuracy and precision should be measured.

  1. Measure and record the depth of the water to the open end of the measuring tube in the well.
  2. Measure and record the height of water in the manometer
  3. Change the depth of the open end of the measuring tube.
  4. Repeat the above steps to obtain several measurements.
  5. Plot the results to determine how linear the system is.

If the results are not linear in the desirable range then: * The configuration illustrated above was not constructed properly * The measurements were not obtained properly * The pressure is inherently not linear over the range of interest

Phase 2

If the system is sufficiently linear over the range of interest then an appropriately ranged differential pressure sensor can be substituted for the manometer and connected to a data recording device of your choice.

Why I'm interested

There apparently is a desire to measure water levels.

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People who did this (1)


huh. i think i can make this out of the air filter parts? how essential is the 'needle valve' versus the screw valve that comes with the aquarium pump?

Dunno if i can do this tonight, but interesting

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The screw valve should BE a needle valve. I suggest a needle valve so that there is a large range of flow control. Most other valves are mainly off or on with a little bit of control in between.

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Go here to see the results from experimentation.

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