We use a domestic private well which has served this house for generations with EXCELLENT water. I would like a visible measure of its water level as in a dry summer it can run nearly dry. Opening the well is a crude matter of turning back the earth and lifting a concrete lid - done once every five years, if that. Does anyone know of any electrical / mechanical device which will report the water level.
Thanks Phil
switches (maybe minimum of 3) arranged one above the other and fixed to something that won't contaminate the water (plastic of some sort, or stainless if you're feeling fancy ). Position this assembly down the well so that the 'lowest' switch is at the 'danger level' - middle one is at 'reasonable' and top one is at 'OK'.
Depending on how complex you want to get, run a 4-wire cable to the switches (one core per switch plus one 'common' core) - and arrange a simple three-LED ( light-emitting diode) indicator to show (say) green for max level, yellow for mid level and red for very low level. Powered from a mains adapter - or even batteries if you want to add a 'push to check level' switch.
If it's a long distance and / or you want to use fewer cores in your cable - you could arrange so that each float switch corresponds to a different value of resistance across a single pair of cables - and then 'decode' this back at the indicator either with an analogue meter (calibrated 'red, yellow, green') or something more complicated using electronic comparators and individual LEDs.
Hope this helps Adrian
======return email munged================= take out the papers and the trash to reply
How deep is it? The simplest and most reliable way to measure water depth is a dip stick. You fit a tube with a screw-on lid at the top and, when you want to know the depth, you open that, put a long rod down through it until it touches the bottom, bring it out and look at how much of the bottom end is wet. However, the limiting factor on that is whether it is practicable to handle a rod long enough to reach the bottom, with a bit still sticking out of the tube.
An alternative, which can work on quite deep wells, is to have a tube, as for the dip stick, but have a length of lightweight man-made fibre cord attached inside the lid. You attach a float to the bottom end of the cord and adjust the length, so that the cord is just long enough for the float to rest on the bottom of the well. When you want to know the water depth, undo the lid and pull the cord out until it is taut, but not so far that you start to lift the float out of the water (the float needs to be heavy enough for you to feel if that starts to happen, but not so heavy you couldn't lift it out with the cord if you want to). The amount of cord outside the well corresponds to the depth of water. It makes it easier to measure if you mark the cord at regular intervals, which can be done by tying knots in it before measuring the necessary length to reach the bottom. Permanent ink marker pens might also work.
Colin Bignell
Tie some cord (nylon/ss) to a float and drop it in the well. Pass the cord over a pulley and add a weight. Mount a rule next to the weight. The float will rise and fall with the water and the scale will tell you by how much.
Mechanical - you simply need to replicate the water level down below at a visible place higher up.
| | fixed | | pointer -->| | | | | | == | | == == | | == pole is sliding == | | == fit in mount == | | == | | | | | | pole | | | | | | / \ / \ / \ | | ball ~~~~~~~~ | | float ~~~~~water \ / level \ / \__/
As the ball float pushes the pipe up and down, the top of the pipe will replicate the water level when compared to a fixed pointer.
An electrical version could be as simple as a ladder of float switches brought up to an indicator panel. The unusual aspect is that the float switches would have to be waterproof on the eletcrical side, they are usually designed for through-tank mounting so aren't.
Owain
There's the pneumatic devices used for measuring the level of fuel in a petrol station fuel tank. Don't know much about suppliers, mind...
Apologies; I'll try that again using spaces instead of tabs.
| | fixed | |
Another, non-contact, method would be to use two lights with focussing lenses.
Fix one light stationary, and attach the other light to a protractor. Depending on the depth of the water, the angle at which the lights will converge will vary. Scale the protractor with the depth accordingly.
The basic technique is well illustrated in the film The Dam Busters, although they fixed the angle and moved the plane up and down.
Owain
I think I recall something like that from when I worked for a company making instrumentation for water companies.
It had a bottle of nitrogen which was gradually bled into a tube that ran to the bottom of the tank/well/river/sewer etc. The nitrogen slowly bubbled out of the bottom of the tube and kept it clear of water. You could then read the depth from a pressure gauge tapped into the tube at the top. I think it also had a chart recorder device and could log for quite some time unattended and without external power.
You could make a similar device out of screenwash tube and a pressure gauge or manometer, and blowing down the tube to clear the water. If you only want a rough guide, you could dispense with the pressure gauge and just judge how much puff it takes to blow air to the bottom of the well.
"Bubblers" were dying out as I arrived on the scene though. Submersible pressure transducers were becoming popular as well as ultra-sonic systems. There were also a lot of float-driven setups with pulleys driving shaft-encoders
Cheers,
Colin.
A paddling duck with a noose around its neck. If regularly queried from above, duck will respond with some noises indicating contentment with the water level. If no noises, assume either low on water (duck is deceased) or the fact that it hasn't been fed regulary (your fault).
A duck friendlier solution could be the items from this lot but ducks might work out cheaper ;-)
you could use a pipe to the bottom, and a manometer at the top. pomp air slowly into the pipe until the manometer settles. That will give the depth of coverage of the pipe at the bottom of the well.
A refinement would be to add a wheel abutting the fixed pointer and in contact with the pole such that rising and falling of the pole is converted into rotary motion on the wheel. An optical shaft encoder and some electrowhizardry later and you can convert the rising and falling water level into a readout.
If you added a flow sensor on your main intake pipe to meter your water use you could then plot one against the other and have a meter show the estimated number of days for which you had water remaining, based on historic usage statistics.
A little HTTP program could then automaticall add extra bottled water to the Tesco home shopping list as required.
Owain
That's how the devices at petrol stations used to work. Not that accurate, but I thought it'd be good enough.
That bubbling idea is a nice solution, with the implied 5yr maintenance schedule all I could think of was a submersible pressure sensor and that was looking like a 300quid solution. An aquarium pump might have enough oomph to provide the bubbles then add a low cost pressure transducer (20quid) and a meter (tenner). Weight the end of the tube to reach the bottom of the well or perhaps a tad higher to avoid sediment and probably put some mesh on the bottom to avoid blockage.
PFO expressed precisely :
No one seems to have mentioned floatless switches....
If you are any good at electronics - The basic idea is a couple of metal probes through which you attempt to pass a low voltage current. If some current passes then the probes are wet. It just needs a mains to 12v tranformer and a suitably chosen relay. Repeat the probe/relay sets as many times as needed to provide enough levels and some sort of indicator in series with the relay contacts (LED's).
With a little more knowledge of electronics you could more cheaply use a series of op-amps instead of relays, to detect flow of current across the probes.
If you go with that, you need gold probes, and a capacitor in series so only ac passes. Use hf to get some i through.
It strikes me the water depth will relate to the pump current required to pump it up, so an ammeter may be all you need, once calibrated.
I would be a bit hesitant about bubbling air thru the well, introducing oxygen and airborne bacteria/fungi into the well.
I'd probaly go with the string and float, but add an external indicator. A bamboo pole above ground with pulley on top, and a smaller weight, will keep the line taut and show clearly the water level.
NT
If you use a pair of resistive rods, the variation of resistance implies depth, also I have seen inductors whose inductance varied used as well.
Looks good. According to the spec. this one can even measure corrosive liquids like Australian wine.
|PFO expressed precisely : |> We use a domestic private well which has served this house for |> generations with EXCELLENT water. I would like a visible measure of |> its water level as in a dry summer it can run nearly dry. Opening the |> well is a crude matter of turning back the earth and lifting a concrete |> lid - done once every five years, if that. Does anyone know of any |> electrical / mechanical device which will report the water level. |>
|> Thanks |> Phil | |No one seems to have mentioned floatless switches.... | |If you are any good at electronics - The basic idea is a couple of |metal probes through which you attempt to pass a low voltage current. |If some current passes then the probes are wet. It just needs a mains |to 12v tranformer and a suitably chosen relay. Repeat the probe/relay |sets as many times as needed to provide enough levels and some sort of |indicator in series with the relay contacts (LED's).
That depends on the cleanness/resistivity of the water. I have had 2 probes with 200V between them in tap water which only passed a few milliamps, not enough to operate a relay. Don't ask why.
|With a little more knowledge of electronics you could more cheaply use |a series of op-amps instead of relays, to detect flow of current across |the probes.
That would be IMO be OK.
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