Depth of water sensing 1

[alternety]

I would like to monitor the water depth in well. Maximum depth is 500" and minimum is 0'.

I have been thinking pressure sensor but everything I have found is quite expensive packaged sensors.

Any ideas on other ways to monitor depth or sources of something I can use for a sensor in a 500' well.

 

[felixc]

My understanding is that you want to be reliably monitoring your well on a regular basis to see how the water level moves vs the water being pumped and the various times of the year, without yourself operating pumps and takling measurements. With a water column of 500 ft, nothing is easy. You may want to speak with the places that sell geotechnical sensors, like Roctest or Geokon. They call them borehole piezometers I think. They are rugged. These things are built with the wiring sealed into them. I'm pretty sure that they have excess stocks that they can sell at a reasonable price. Then all you need is an interface for a computer to read the output of the piezometer. In case of problem, you will not question the quality of your setup instad of the water pump or the capacity of the well itself.

 

[itsmoked]

Are you amused? heheh.

I have delt with wells before.. And the sickening feeling when something won't come back up. My old boss's well, about 2 months after an earthquake we tried to pull the pump for service. Nothing doin. We used a winch on a truck and it lifted the truck.

The only thing I can recommend is that when a pump starts the riser generally whips all over the place. Perhaps a few starts while jimmying will get the job done... Otherwise it's cheapo TV camera on a cable. Don't get it stuck too. :0

What do you mean by "low water" sensor?

By the way do you have a flexible riser? Just pull the whole dang mess with a winch from 500 ft away. Tie the sensor to the pump where you want it and chuck it(er.. lower gently) back down. If you have rigid pipe..... Go fish.

 

[Warpspeed]

Hehehe, you have the well, tried making a wish ?

Sorry alternatey, I could not resist.

Itsmoked is right, putting anything down there is going to be a big drama. Maybe I am paranoid, but the thought of having a "sealed for life" pressure transducer down a big hole just seems like an unnatural act.

How about hauling up your pump (a very big job) and fitting both a pressure transducer plus wire, and a bubbler pipe with plastic cable ties to the pump cable, and sending the whole lot back down. If the transducer works, the problem will be solved. If it craps out, there is nothing (??) that can really go seriously wrong with a bubbler.

 

[alternety]

Remember - just because you are paranoid does not mean they are not out to get you.

Low water sensor - that device which detects that the water level is about to become lower than the pump inlet thereby causing catastrophic destruction of the pump.

Pump is on the end of 500' of solid plastic pipe.

Many $thousands to pull pump assuming a will drilling rig can actually get to the hole. The well was drilled before the house. Spouse and previous owner required dowser vs where I wanted it. Dowser said drill here and in some reasonable depth (I think around 100') you will get limitless water. Result - 605' no water and too close to house.

There are things to be said for city water (don't go there - not available and will not be).

My day has not been good.

 

[Yashu]

I seem to remember an IC device which can measure VSWR on a bare wire immersed in water to determine the height of immersion. It used some kind of AC signal to avoid buildup of corrosion. I think it was from National semiconductor.

 

[Yashu]

Still like the BrianR technique.

Simple enough. Then, put "an inlet" valve at the top and crank in air every day or so from a meaty pump to make sure the pipe stays full of air and combat the leaks.

 

[Warpspeed]

So the pump pipe is rigid? Oh dear, I thought it may have been something that could be hauled out for maintenance.

It may not be very helpful, but another idea has just occurred to me. One way to measure the displaced air would be a counterweighted gas bell. As the well falls, air would be drawn in and the gas bell would sink in it's pond. As the well rises the air floats the bell higher.

If the weight of the actual chamber is counterweighted the pressure inside could be made extremely close to atmospheric, so it would have no real natural tendency to leak.

All rather primitive I know, and it would be huge, but again it has the simple virtue that nothing need go down the actual hole. You would just need a large open ended tank with similar total volume to your well, and a large water filled pit in which to float it. To measure well height you just need to look out of the window. It could even be built right over the well head ?

I get ideas like this all the time, I cannot help it. One day they will come for me.

 

[alternety]

warpspeed - I know what you mean about the ideas. I find that a couple of large gin and tonics can reduce the volume of the voices (or at least make them seem more reasonable). I also understand there are muchrooms that can reduce or increase the voices; depending on the base state.

There are a real interesting bunch of ideas in this thread. It really has been quite interesting. Anyone that can get the damn probe out of my well will get all the beer he or she can hold. Once you have stepped away from the well of course.

 

[itsmoked]

Keep an eye out the window....

 

[itsmoked]

alternety; are you telling me you glued length after length of plastic together?

If you used continuos pipe off a roll then I can't see why you can't just pull the pipe out over a roller in one smooth continuous pull in about 10 minutes... Heck, I'd pull that pump every couple of weeks just for fun!

 

[BrianR]

alternately,
this has been a very interesting topic although some of the ideas have bordered on silly, in light of the original concept of simplicity and low cost. What is the implication of abandoning the stuff jammed in the pipe?

At one stage I wondered about using one of those laser distance measuring devices but thought cost might cut it out.

I am convinced though that the best solution is a waterproof pressure sensor with moulded cable dropped to the bottom. No compressor needed and no pipe.

2nd best is measure the air pressure in the pipe and blow air in until the pressure no longer increases, meaning bubbles are now coming out the bottom. Use pressure < 2psi (50" water) to signal pump off. This needs a 250psi air compressor and pipe proof to that pressure as well.

 

[alternety]

The implication of abandoning the stuff in the pipe is I can't use the well. The house is unlivable. Given the problem I have had getting a realtively small device down the hole, anything else is probably not feasable. Getting the probe down did not work at all well even before it got stuck. Either the pipe and/or bore hole are not straight or the power wire is all over the place. I might be able to do something with a solid pipe but it would immediatly go beyond what I can do by hand (too heavy). I suspect the sensor is caught in a piece of the power wire going to the pump. It is the only thing down there I can think of that could so this.

I agree about the pressure sensor. A tube with a bladder on the bottom might also work. This keeps the electronics on the surface.

I am going to look at doing something to use the original sensor to sense low water. It used a current between a probe just above the pump and the pump body to determine if the well was empty. The new well controller does not work with the old sensor although the vendor claims it is backward compatible. The only alternative to this is to pull the pump and fix everything.

Right now I am really in a world of hurt. It is way to dangerous to pump without a low water sensor.

I have many other really pressing issues with getting the house finished and I really don't need this.

 

[Yashu]

Yet another idea:

http://www.iti.northwestern.edu/publications/tdr/1994_papers/narm_1.gif

 

[Yashu]

http://www.geneq.com/catalog/en/water_level_102.html

 

[itsmoked]

Present headache aside. My condolences. I have another suggestion for depth monitoring.

Besides a correctly tie wrapped every 5ft, submersible 4-20mA pressure transducer for $359 plus $1.50/foot for factory installed vented waterproof cable that is.

If your pump pumps with a free head. Another words into the top of an atmospherically vented tank the head is fixed.

The amount the pump can produce is directly related to the water column height. This means you can use a flowmeter at the tank and monitor the flow to give you the water depth in the well. You can zero it by monitoring the flow and running the pump until the water drops down to the pump and the pump goes dry which won't hurt it if you stop it the instant you notice the first slug.

 

[Warpspeed]

That may not work if the pump is a screw type with a constant Rpm and displacement. But motor current may well be reliable variable because the pump has to make up the height difference between water level and well head. This idea has already been proposed by "adc" in a previous post, and it probably deserves some further investigation.

I still think that actually getting anything down the well will be problematic, and that includes optical, acoustic or microwave pinging of the water. It looks like the existing pipe wanders all over the place effectively blocking the hole. That also probably rules out floats and counterweights mounted on wires.

 

[itsmoked]

Warp; they use positive displacement pumps down private wells?? I thought they were ALL multistage centrificals.

I could see the current having a nonlinear aspect. But maybe not.

 

[RobWard]

In the old days, miners took canaries into the mines to warn of "poison gas" build ups.
If the bird stopped singing: run.

So (providing you can unblock the pipe) you need a little cage, a canary, and a long length of string marked off every foot or so.

Lower the canary down. When it stops singing: voila! water!

(Reduce costs: don't buy a new canary every day: buy a few breeding pairs and you get a limitless supply)


Any joy getting the stuck sensor out?
I know the feeling when something gets wedged where it shouldn't and you just can't shift it. Not nice.
And how often is it that it that it would only need the tiniest push in a different direction to free up, but you just can't reach it to do that?

Let us know how you get on. Sorry I can't offer any actually good advice.

&quot;I love deadlines. I love the whooshing noise they make as they go past.&quot; Douglas Adams

 

[Warpspeed]

Don't really know, but either flow or motor current must change, because the required amount of work changes.

Either one or the other must surely give enough variation to be a useful, if not highly accurate indicator.

 

[itsmoked]

See that's where I'm having trouble because I think the work stays almost constant. What will happen as the standing water column drops and the pump has to pump the water farther up, the amount of water will drop, (flow) to keep the work, (motor-hp) the same. So the current will just sit there at the motor rated current.