Quote:
Originally posted by TerraMex
The initial testing with these types of sensors, magnetic displacement in flow measurement (to be more precise, but it can be interpolated to here), using a magnetic sensor, resulted in precipitation of ions on the surface of the magnet (which is isolated, but doesnt matter as long as the field exists), distorting the field, and giving inaccurate readings, or even reducing the field considerably , with some extra EMI , making the sensor useless.
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I'm not sure what qualifies as "initial testing," but I can tell you that I've done the same thing with ferromagnetic stirrer-bars in solutions of water and both cationic and anionic chromophores, and I've never gotten "ion precipitation" other than the expected EM bonding on the magnet's plastic casing (aka, the stuff stains.) How strong a magnet are you using, for god's sake?
Seriously, the sort of small permanent magnets you're going to use for this (~0.01 T) will *not* affect water that has a conductivity on the order of tap water. The only troubles I've seen with magnets this size are with fluids that are by themselves ferromagnetic - certain types of fluids for photographic film deposition, for example. I find it unlikely you are detecting evidence of the Hall effect unless you're strapping an NMR to your reservoir or have some very classy detection equipment. I find it *very* unlikely such an effect in this magnet could ever cause the magnetic field a centimeter from the magnet to reduce ten times over or reverse entirely, which is the only way such a simple solution as wymjym proposes could not work.
You're suggesting that the magnet wymjym suggests has such a *huge* charge flow and density about it that it can function as a galvanic cell? Where would the energy come from? You're also suggesting the layering that would be done on it would *distort* the magnetic field. How and why would a magnetic field arrange ions about itself in a pattern *contrary* to its magnetic field?
Look, I'm not an expert on magnets or electricity, but this whole discussion about how scary magnets are reeks like those new-age magnetic bracelets used to cure stupid people of having wallets.
http://education.magnet.fsu.edu/faq/index.html
Alchemy