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Electronic water level gauge for well Answered

I have a 32m deep, 95cm diameter well, that is covered with two heavy concrete covers. The water depth is about 20m down from the surface. I cannot easily access the well to sound the depth or visually check the water level. I would like to build an electronic water level gauge that will tell me the amount of water in the well. I can then regulate watering accordingly. It was suggested to me that I use a washing machine pressure transducer but I have no idea of the circuit required. A refined solution would send data to my PC !!!! I have 240v AC supply to the well pump. Any ideas? Steve

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AndyGadget (author)2011-06-15

 
Coming at this from a different angle :-

Long cord (depth of well) with a ball float on one end, counterweight on the other end.  Pulley at the top of the well with the cord over it (possibly a couple of turns around to reduce slippage).  Pair of switches (mechanical or opto) by pulley to provide rotation count and direction indication.  8 pin micro to interpret and scale revolution information feeding serial data to LCD display or PC.

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freethetech (author)2011-06-14

Couldn't you use a weight-scale? Water doesn't change weight.

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11010010110 (author)2009-01-04

i have no clue how to sense water level with the washing machine sensor. maybe it can work like this - you connect it to a long thin air pipe which end is dangling at the level you want (and with some weight connectd to it so it does not float). when water closes the pipe the pressure rises and it switches the sensor electrically the senso is just an on off mechanical switch activated by peressure. you can blow into it and hear how it clicks other ways i thought of long wires with small current on them (thru large resistor). the water conducts tiny current in the wires that touch it pros : easist to make cons : electrolysis destroys the ends of the wires quickly. a drop of water or something wet that stuck on the wires may give false positive laser reflection. you aim a laser pointer with a slight angle into the water. the place of the reflected beam depends on water level. you get it with a series of photo sensors. move a bit the lens on the laser so itll be a tiny bit out of focus and you get light spot instead of single point pros : nothing that can destruct cons : depends on the silence of water in the well. the slightest wave on the water surface (like from falling drop) affects the results simple reflection. a floating object with bright color is placed in the water (and connected to the top with wire so it'll not get lost). light source and photoresistor are placed above. the amount of light that gets to the resistor depends on the distance of the reflective object pros : its smooth and not limited to sense a limited amount of levels cons : float can disconnect from wire and get lost in the well (possibly clogging it). results affected by dirt on the float and vapors of water above sound echo delay measurement pros : very high accuracy cons : complex electronics (way more than other options)

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user

I really like that fourth option in the picture. Anyone got a circuit diagram showing how to create a ultrasonic liquid level tester. I have one of those portable air conditioners that sits on the floor. I thought it was a great idea, never again have to worry if my next apt has horizontal or vertical windows. The BIG problem is you have to do one of the following. Empty the drip bucket on a regular basis and if it fills up while you are asleep, no cooling till you wake up. Or elevate the unit so that its bottom is higher than the bottom of your window so you can put the built-in drip hose out the window. I can't find or build a stand strong enough to safely support this heavy thing up high (I live in an apt, no workshop) and too many times it has filled up during the night and it was hotter than outside when I woke up. What I want to do is make a liquid level sensor to activate a small 5 volt pump ($15.00 on eBay) when the liquid hits a set level and keep pumping till it falls to another set level. I have some different circuits using either LM850's or 555's. They both look good but I was thinking that an ultrasonic sensor would just need to most likely have two pots adjusted to set the high and low levels. Anybody got any ideas?

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user

Ultrasonics is not for a short range system. Stick with conductivity probes, or even slicker, capacitance.

Steve

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NachoMahma (author)110100101102009-01-04

. You came up some very good ideas. . > air pipe . Where I worked we would attach a low-flow regulator and a pressure transmitter and switch. Back-pressure varies with height of liquid column. Pressure switch for alarm. Without more info, I'm guessing this will be the best bet. . > long wires with small current . Should work well, but it has to be constructed to fairly tight tolerances. Calibration will drift as the probes collect dirt, algae, &c.; . > laser . A stilling well should take care of surface turbulence. Most such sensors will have averaging/filtering built-in for minor turbulence. Probably not a DIY project, but laser ranging equipment is reasonably cheap nowadays - depending on your definition of cheap. . > simple reflection . hmmmmm Never used that for distance measuring. Dirt accumulation on the target would probably cause calibration problems. . > sound echo . Reflections from the walls will raise Hell with this one. More suitable to large tanks.

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tekbird (author)2009-07-24

sound echo seems to be the right choice, which is mostly independent of other limiting parameters...

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tekbird (author)2009-07-24

if we can find the height of the water column, we can set up values to calibrate it and find the volume of water right?

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jeff-o (author)2009-01-22

I've seen laser distance measuring devices for sale at hardware stores for a very good price. I don't know how you would transmit the data to your PC, though.

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SteveG31530 (author)2009-01-09

The water level varies from say 15m in winter to only 1-2m after the pump has been running in summer. We use the well to water the garden. 1% accuracy means 15cm in winter so this would be a good target. I really want to find the height of water. The well walls are smooth concrete sections. If I can measure the height of water then I can try different watering programs. I might get more water if I run the pump twice a day`. It is very difficult to guess what is happening when everything is at the bottom of a deep dark hole.!

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NachoMahma (author)SteveG315302009-01-10

. That's ~500 inches of water or ~18 PSI (I don't think in metric). The deepest bubble tube I've worked with was ~3 m, but you should be able to get a reasonably accurate reading. May require some recalibration 2-3 times a year.

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11010010110 (author)NachoMahma2009-01-10

i guess bubble pipes work better the deeper the well is but how to get a reading off it without an array of washing machine sensors ?

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NachoMahma (author)110100101102009-01-10

. All you need is a digital pressure transmitter (or an analog xmitter and an A/D (analog-to-digital converter)).
. Omega Engineering and McMaster-Carr sell what you need.
. You may be able to find a cheap, used transducer and/or A/D at an industrial supply store.

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NachoMahma (author)NachoMahma2009-01-10

. PS: Ask around at local plants and you may be able to get an old transmitter that will no longer calibrate to their specs but would be good enough for what you are measuring for free.

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NachoMahma (author)2009-01-04

. How accurate do you need to be? +/- 1mm? +/- 1m? . Do you actually need to know the height of the column or do you just need to know when it reaches a certain level(s)?

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