pH meter for Oily Water Service 1

[khan101]

Hello,
I am looking for a pH meter for oily water service. This stream has 1-4% bitumen and has 10-15% sand. The line size is 16 inch and line pressure is 70 psig. Temperature is around 60C. I was thinking about installing the probe into a slip stream with an isolatable system. Any suggestion?

 

[m777182]

The problem encountered is not temperature nor pressure or sand but bitumen and oily phase.It appears as organic emulsion of about colloid size. A colloid particle (or emulsion droplet) is surrounded by its specific ionic layers that change the distribution of H+ ions arround it. Consequently the fraction of the pH electrode surface that is covered by oily colloid will not sense activity of H+ ions of the bulk solution that pH value coresponds to but will measure the activity of H+ arround the colloid adjacent to the electrode surface and the reading of the instrument will consist of a fraction of real H+ activity and a fraction of H+ activity of the ionic athmosphere of colloid particles.
Many times a good correlation exists among pH and conductivity.This property is much more easy to measure and with contactless electrodes a few percent of emulsion will not really spoil the measurement.The sand that is in a case of pH measurement beneficial because it cleans the surface of the electrode permanently could be removed by a small inline separator.
m777182