On PH measurement, there are no pH complications are created equal. The list below illustrates the types of problems that you can expect when measuring pH and how to handle them.

1) pH Instrumentation is frequently the source of disturbance for pH systems, through repeatability error, measurement noise, or valve hysteresis.

2) In-line pH loops will oscillate, regardless of controller modes and tuning, if setpoints are on the steep parts of the titration curves.

3) pH electrode submersion assemblies with unencapsulated terminations below the liquid surface will eventually have wet terminations.

4) Reagent control valves that are not close-coupled to the injection point on in-line systems will cause reagent delivery delays large enough to describe the tools of your trade n words that may seem foreign.

5) You need either a flow meter or a seer to diagnose reagent delivery problems.

6) Flow feedforward signals should be multiplied by pH controller outputs and employed to operate reagent valves directly or to establish reagent flow control setpoints.

7) Transportation delays to pH electrodes in pH analyzer houses will exceed mixing deadlines - such that increasing comfort in checking the pH electrodes is offset by decreasing comfort in checking trend recordings.

8) Injection electrodes should be preferred to sample holder assemblies whenever possible to reduce maintenance problems and improve response times - but not all injection electrodes are created equal.

9) Large tanks are fine if you don't have to control them; use the volume upstream to reduce reagent consumption or downstream to reduce control error. If you can't make up your mind where to use one, put it downstream.

10) Install one or three but never two electrodes for pH measurement.