Info on pH process, was pH titration/control

Patrick Viskens wrote: > To control pH with a PID controller use a non linear PID algorithm. You set deviation limits around your setpoint. When the measurement has a value in between the limits the proportional band of your controller will be set to a higher value ( 3 .. 5 times more ) so you work slowly to your desired setpoint. The output of the PID controller has a split range which has two time proportional output contacts. The non linear PID algorithm with good tuned time proportional output contacts does the job. Depending on the kind of application ( installation ) you can use Otto Schmitt dead time compensation, feed forward compensation, ... < Dear Patrick, Your reply is interesting as I am also planning to build a pH process unit for teaching purpose. The application and setup is exactly the same. Could you please advise where can I get more information on this subject. My mixing tank will be 80 litres only. Cheers Regards, C.P. Ku