Ground loop interrupt pH electrodes 1

[magrace]

In our process, we make a solution that is controlled by pH. We have ground loop problems as the tank is made out of wood. We have been using a pH probe that has ground loop interrupt but we have found that a significant amount of the probes we get from the supplier have manufacturing defects (in one case over 60% of the probes sent to us were defective). I'd prefer not to post the supplier.

I am having problems locating probes that have ground loop interrupt outside of this supplier. If anyone knows of any companies that have sensors with ground loop interrupt, please message me, or please post your tips to get around this problem!

 

[m777182]

A possible source of a ground loop problem has to do with the reference electrode input to the amplifier: this point is usually not at the ground potential, but is with a resistor of a few kOhms separated from the ground in the amplifier circuit side. On the other side, that is in the liquid you are trying to measure, the current flows by the irregular path, at each instant through the most conductive path. So a battery powered portable pH meter with no grounding at all should not exhibit ground loop problems though it is not an industrial solution. Some pH meters have a high impedance input for both electrodes with somehow floating zero or ground. They work better. The ground you are using should be exactly the potential of your vessel and not a sort of common plant ground.
Sometimes a streaming fluid can be a source of current to your electrode. Sometimes two different metals in your solution present a source of potential (two half cells) that interfers with your pH measurement. If your solution is colloidal or contains two immiscible liquid phases then expect troubles.
m777182