pH Control

Mettler toledo is one company that is probably well set up to deal with this but the easiest way to find out is Search Globalspec. Just don't forget to tell them the problems you're encountering as well as the parameters you've listed.

As pH is the negative log base 10 of the hydrogen ion concentration, if the conductivity is <...very low...>, pH is barely relevant as a measurement, unless there is something that hasn't been shared with the forum?

Thanks for the comment,

As I said the sugar juice has low conductivity due to its pass by a ion exchange resins. After this stage the juice pass to an evaporation stage, where it can reach temperatures as high as 115ºC and it is known that the pH of sugar go down with high temperatures due to hydrolysis, so its neccesary to add caustic soda to regulate pH on a residence tank, and we have accuracy problems on the measure of pH at that condictions (mainly high temperature, and high brix).

So we drink-en this stuff?

Don't worry. All sorts of things are added to stuff that is drunk or eaten every day - with good reason.

There are many manufacturers of pH equipment, like Emerson/Rosemount, ABB, Honeywell and others.

The issue that you need to make sure that you do not contaminate the sensors with the sugars, you may need a in line cleaning system or something to purge the sensor tip.