Water level sensor

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bengaltiger
 
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Water level sensor

Post by bengaltiger »

I'd like to put together a sensor that monitors the water level of an overhead water tank.
It has to be rugged; the conditions are fairly harsh (temperatures vary from 32F in winter, to 120F in summer).
And it has to be hands-off, requiring basically no maintenance.

Ultrasonic is out, because condensation is an issue in summer. Any conductive technologies are out, since the water has dissolved minerals (i.e. is quite 'hard'), and over time the performance would degrade.

So I've been thinking of a pressure sensor, suitably sealed, placed at the bottom of the tank. I could calibrate it once, and then forget it. Any reason why it would not work? It doesn't have to be *super* accurate; as long as it gives a rough idea of the water level to within an inch or two, it should be fine.

It would be connected to an Arduino or an rPi, with wifi connectivity to a system that displays the water level. (I have many more questions about that, but baby steps... :) ).

Thanks!

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adafruit_support_bill
 
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Re: Water level sensor

Post by adafruit_support_bill »

I've been thinking of a pressure sensor, suitably sealed, placed at the bottom of the tank.
Why not a pressure sensor with a tube extending down into the tank. Some pressure sensors are designed with 'ports' to attach tubing. If you extend the tube to the bottom of the tank, the pressure in the tube will be proportional to the depth of the fluid in the tank.

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bengaltiger
 
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Re: Water level sensor

Post by bengaltiger »

adafruit_support_bill wrote:
I've been thinking of a pressure sensor, suitably sealed, placed at the bottom of the tank.
Why not a pressure sensor with a tube extending down into the tank. Some pressure sensors are designed with 'ports' to attach tubing. If you extend the tube to the bottom of the tank, the pressure in the tube will be proportional to the depth of the fluid in the tank.
I figured, the less parts, the better. It will be maintained by people who have basically no knowledge at all of this stuff. I want it to be as hands-off as possible. So my thought was to get a pressure sensor, heat-seal it and then connect it to the controller.

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zener
 
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Re: Water level sensor

Post by zener »

I have quite a bit of experience with this. Bill's suggestion is very good. There may be some technical advantages to your idea, but there are also technical challenges. One issue is, if your submersible sensor has no atmospheric reference then it will be affected by changes in atmospheric pressure. This will introduce errors which may or may not be acceptable. The submersible sensors we use have a vent tube in the cable to take care of this.

Another issue is keeping the device sealed. We have bought some very expensive ones that leaked eventually.

The dip tube idea is probably a better way to go. This system is used in washing machines as well as much nastier environments and holds up well.

However, your idea will work, with the limitations I stated.

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adafruit_support_bill
 
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Re: Water level sensor

Post by adafruit_support_bill »

I figured, the less parts, the better. It will be maintained by people who have basically no knowledge at all of this stuff.
My experience with submerged sensors and leaking seals is similar to Zener's. Adding a dip tube and keeping the electronics dry is likely to result in a lower maintenance system.

http://www.robotshop.com/en/differentia ... 0-kpa.html

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