pH probes

[sparky970]

We have many pH/ORP applications in our plant. We consistantly have reliability issues on our process streams with a high sodium content. We have used Foxboro Dolphin series, ASTI, and Yokogawa. Anyone tried Metler-Toledo? Any suggestions as to solutions for better reliability?

 

[JLSeagull]

E&H offer a smart pH/ORP sensor technology called Memosens. The Memosens claims include improved sensor life, less frequent calibration and service by less specialized techs instead of analyzer specialists.

 

[danw2]

I can't speak to the sodium issue, but I've found that the majority of pH probe problems to be related to reference junction pollution or depletion.

I've gotten extended life from the Honeywell Durafet solid state probe because its reference junction takes a large volume and can be refilled, which we do at least once, sometimes twice.

I got a datasheet for yet another style probe that uses the 'axial ion path" on the reference side for situations that pollute the junction, more than depleting it.

 

[ash9144]

I assume that the sodium issue is build up on the probe. I've seen issues with build up on pH probes in many cases. Usually the best bet is to find somewhere to install the probe to increase the fluid velocity to reduce scale build up. Recirc lines or even small bore pipe specifically for your pH probe.