Measure water level in 10m deep well, Ultrasonic sensor?

[PiNinja]

Hi,

I am in the startup of creating a project where I want to measure the waterlevel in a well at my family's cabin. The well i rather deep, 10.5 meter and about 1.2m in diameter. Maximum water level is expected to be about 7 meter and 1 meter at its lowest point.

So I am looking for a sensor that will be able to measure about about 9 meter down to the water level. If I manage to place a sensor at expected maximum them 7 meter could do, but I rather have the unit easily accessible at the top.

I am thinking a ultrasonic sensor would do the job? But the once I have seen so far appear to have a max range of 5 meter. Do you know of any sensors that would be suitable for the project? If not a ultrasonic sensor is not suitable I would be happy to hear of other options which is fairly easy to setup.

Kind regards

[terryking228]

Hi,

Another typical approach is to put an absolute pressure sensor at the bottom of the well. On a wire...

From school Physics:  32 feet of water is 14.7 PSI.

[PiNinja]

Not sure I have heard of that before. How does it work? Will it be able to measure the level reasonable accurate to +-5 cm?
Did a quick google but not quite sure what to look for, do you have an example?

[Wawa]

All the electronics can be put inside the house if you use a bubbler system.
Google "well bubbler" or "Arduino well bubbler".
Leo..

[Railroader]

Use a 10 meter long tube containing air and a preasure sensor applied at the top, above the water level. Still the sensor needs to resist the climate in the well.

[saildude]

PS: since a bubbler measures the measures the height of the liquid from the bottom of the tube - you want the bottom of the tube you should make sure the height of the tube remains the same and is repeatable if you take the tube out and reinstall it

[Railroader]

Of course!

[Wawa]

A small airbrush pump could be used to deliver the required >1bar (14.5psi) pressure.
An aquarium air-stone and the end of a thin food-grade hose could be dropped in the well.
Some extra weight might be needed to make sure it reaches the bottom when the hose/stone is filled with air.
Leo..

[terryking228]

Hi,
Interesting idea (bubbler) that I had not heard of...

So, I really DO want to remotely measure the water level in my well (3 ft diameter, 10 feet deep)..

So, I understand I do this:

- Install a long hose from the wellhead to the house, bring hose inside near my Home Automation computer.
- At the well, connect the hose to a rigid tube (say 3/4 inch white PCV) long enough to reach the bottom of the well.  
- At the house connect some piping (regular PCV plumbing stuff) as a "Tee" with one port to a compressed air supply and other port to an electronic pressure sensor (1 atmosphere 15 PSI OK for my shallow well).
- Feed enough compressed air into the system to be sure air is bubbling from the bottom of the well.
- Measure the pressure at the sensor.

Right??

In my case I have compressed air fed to house and barn. My wife resisted having it in the kitchen, dunno why.

So if I use a typical solenoid air valve, I could have my Arduino Mega (usually loafing along anyway) turn on the air, read the pressure and wait for it to stabilize, turn the air back off.

Caculation:

See: http://docs.bluerobotics.com/calc/pressure-depth/

So, for example, 8 feet depth is = 3.47 PSI

So a pressure senor good for 10 PSI or 1 atmosphere would be fine...    

Does this make sense??  Errors?

[Wawa]

Rigid tube is not needed. A thin aquarium air-hose will do. Just keep it under some tension (straight).
A small blood pressure air pump might be ok for 10feet of water (0.3bar).

You don't need much air flow, you just need to overcome the pressure of the head of water.
An air compressor with a valve and flow reducer (clamp on the hose) could also work.

A 5psi sensor (with buildin instrumentation amp) would be ok for 11.5 feet of water,
and would give twice the resolution of a 10psi sensor.
Leo..

[saildude]

@terryking228

That is almost the exact same design I have sketched out for a winter project and am ordering parts for now, I however plan to record the water level and might display the height in a graph on a screen.

So I think you are on the right track - the advantage I see to a bubbler is the electronics can be remote mounted where the environment is better for the electronics