What is needed to measure distance between two electrodes imersed in seawater ? I have tried measuring the voltage across the path (a suposed resistance) with a constant current source (about 10uA) passing the water to GND of circuit. (the resistance is suposed proportional to distance of electrodes) The probes are 100Hz reversing switched to avoid polarization. And I am using AG/ AGCl pellets as electrodoes. But until now I could not have stable results. What may be wrong ? Could someone help ? Thanks
The AgAgCl sinterized disks was choose because it is very used as reference electrode for seawater potential measurements (cathodic protection) with very good results and low maintenance, but I really dont know if it is the the best for my application. The suface area is about 1 cm2 then we are expecting about 20 Ohms per cm of distance in seawater. With a 10uA as (AC square wave) current source between electrodes voltage will range from about few milivolts up to 1 volt at 50m. As you see the potential is bellow of water electrolisys. What you mean "with a lot of corrosion protection" for Stainless Steel plates ? I understand that salinity, temperature etc could vary in the media but these factors are not expected to change so quickly and I also intend to use a known distance sensors for reference as well averaging the measures. I intend use this sistem in a dynamic environment where the reletive speed between sensors or the flow may be about 10 cm / sec. What you think about the method ? There are a better one ?