Water Level Detection

[colin55]

You make a very simple pressure sensor yourself. Get a metal lid.
Place a piece of black electrostatic (resistance) foam on the lid and cover it with a piece of PC board. Now connect the PC board and lid to your monitoring circuit.
Place a sheet of rubber (from a balloon) over the lid and sink the detector. The pressure of the water will push on the rubber and the PC board and squash the foam to generate a differing resistance.

 

[blueroomelectronics]

What was wrong with using a simple float? It's reliable, cheap & safe.

 

[premkumar9]

What about brass rods?

 

[premkumar9]

What was wrong with using a simple float? It's reliable, cheap & safe.

I need an electrical signal.

 

[blueroomelectronics]

I need an electrical signal.

Use a potentiometer or switch. Both carry an electrical signal just fine.
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[Boncuk]

And now the solution to measure 5m of water height with that method, please.

 

[premkumar9]

Use a potentiometer or switch. Both carry an electrical signal just fine.
**broken link removed**

This is the method I considered first. But had some practical difficulty with the huge tank of our customer. Anyway thanks.

 

[blueroomelectronics]

What about a double articulated sensor with two pots.
something like this
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[premkumar9]

What I plan now is for the first supply of two systems, I may go for a conductive type sensing. Later on will try to develop a better and more reliable method and if necessary, will replace the first ones (sensors alone). This strategy is to meet my time frame.

 

[premkumar9]

I had supplied my equipments with conductive type sensors. These sensors installed at 4 tanks and working for the last 4 months. Can anybody suggest some sensing method by which I can fit the sensor above the water level and get a reading of the water level (like ultrasonic sensing). Is there any such standard devices available.

 

[Reloadron]

If conductive sensors are working for you that is fine. There may be an ultrasonic method that would work, bouncing a signal off the liquid surface.

Something I have used is delta pressure and simple pressure. This works well and is along the lines of how a washing machine knows it is full. If you have convenient access to measure the pressure at the base of the tank, the pressure will be a direct function of the level of the liquid in the tank. Really matter of budget.

Ron

 

[premkumar9]

If conductive sensors are working for you that is fine. There may be an ultrasonic method that would work, bouncing a signal off the liquid surface.

Something I have used is delta pressure and simple pressure. This works well and is along the lines of how a washing machine knows it is full. If you have convenient access to measure the pressure at the base of the tank, the pressure will be a direct function of the level of the liquid in the tank. Really matter of budget.

Ron

In my case, all the tanks are huge and I wanted to avoid fitting anything inside water. Accuracy is not very critical. I was just thinking of using some reflections from water surface or so and looked for suggestions from experienced people .

 

[mneary]

Have you looked into the method used in cameras for range finders?

 

[Sceadwian]

Camera range finders are ultrasonic generally.I'm not sure if that'd be practical for the precision or speed he needs, the signal processing end of things would be a little complicated.

 

[premkumar9]

Ultrasonic sensing

Ultrasonic sensing may be possible. I expected remarks from somebody who tried this method.

 

[ardhuru]

Finding the ultimate sensor that would give a quantitative reading of a liquid level (and yet inexpensive) has also been a holy grail for me.

BTW, I have also considered ultrasonics, but am apprehensive about the sensor's longevity in the damp environment, even if it mounted a few feet above the maximum possible water level. Considering the very nature of its job, the diaphram might get severly influenced by the ambient moisture, I feel.

Wondering if this apprehension is justified, or am I being paranoid?

Regards,

Anand Dhuru

 

[premkumar9]

Finding the ultimate sensor that would give a quantitative reading of a liquid level (and yet inexpensive) has also been a holy grail for me.

BTW, I have also considered ultrasonics, but am apprehensive about the sensor's longevity in the damp environment, even if it mounted a few feet above the maximum possible water level. Considering the very nature of its job, the diaphram might get severly influenced by the ambient moisture, I feel.

Wondering if this apprehension is justified, or am I being paranoid?

Regards,

Anand Dhuru

I also have the same doubt. Sealed types are available. But too expensive. But what was your experience? Did it give a good and reliable echo from the water surface (other than the reliability issue)?

 

[ardhuru]

I didnt even try, since I felt fairly certain about my suspicions.

There's a superb, very easy to use product called the Etape, but its ridiculously expensive...

Still have a couple of ideas I'd like to play around with!

Regards,

Anand

 

[mbarazeen]

just a suggestion, you can use an IR source and few sensors as shown in the arrangement. but the water surfce flaxuation may disturb your sensors. may need some guide before the snesors too.

 

[ardhuru]

Hi, thanks, thats a good suggestion.

I've also looked at IR in the past, but what I'd like to have is a 2 (or 3) wire sensor that can still detect multiple levels. In your suggested scheme, one would require one wire for each level to be detected.

I vaguely remember having read a technique, but cant find the article anymore. Basically, you use just one source, and one detector (3 pin demodulator). You begin by modulating the transmitter at its optimum frequency (38 KHz?) and keep transmitting a single character, and keep reading the pings. You then keep reducing the modulation frequency till reliable pings stop. The difference between the ideal frequency and the one at which you no more get a ping would then be a function of the distance.

Hoping to try this out the next couple of days!

If anybody does experiment with this, it would be nice if we can pool our findings.

Regards,

Anand Dhuru