An Error 2 means that the calculated asymmetry potential is outside the acceptable range. The Asymmetry Potential (AS), also referred to as the millivolt offset, is an indication of the condition of the reference electrode. Theoretically when the electrodes are placed in a pH 7 buffer, the millivolt output from the electrode pair (pH and reference) should be zero. Some of the causes of the millivolt offset are depletion of the Potassium Chloride (KCl) from the reference electrolyte or the reference electrolyte becomes poisoned with the process solution. When the millivolt offset is +/- 30mV, it is advisable to replace the reference electrode. The correction limits of the EXA pH analyzers are +/-120mV. Outside this range an E2 error message will appear on the second line display.
Possible Causes of Error:
- Bad Buffer 7 (zero buffer).
- Reference Electrode is too old and out of acceptable limits.
- Reference Electrode is poisoned or damaged.
- Bad wiring or Electrode Cable is faulty (bad isolation).
- Solution Ground Electrode (Post) is coated, dirty or connection is faulty.
- Clean pH electrodes in 5 - 10% HCl solution or Muratic Acid.
- Replace Reference Electrode.
- Check wiring connections and replace Electrode Cable if needed.
- Clean Solution Ground, check wiring connection and replace if faulty.
For further assistance, please contact Yokogawa's technical support center at email@example.com or 1-800-524-7378.
Designed for 2-wire (loop powered) system configuration. Standard mA (4-20), HART, Profibus, and Foundation Fieldbus communication available.
The FU20 and FU24, all-in-one pH and ORP, sensors show how Yokogawa applies the motto "Simple is best" to sensor technology.
The cation differential pH and ORP sensors were designed for difficult applications where conventional sensors are ineffective. These include measurements such as brine solutions to applications as diverse as electrolysis processes and cheese manufacturing.
Model Name: PH200G
The PH400G EXA PH intelligent pH analyzer is a highly reliable advanced function pH measurement system designed for wide application in all industries such as for medium-scale waste water treatment system, and general-purpose pH measurement and control systems.
The PH400G features highly effective built-in functions for electrode diagnosis that are similar to those of the EXA PH202 2-wire pH/ORP analyzers. These functions monitor sensor errors even while pH measurements are in progress, enabling more highly reliable pH measurement.
The PH400G also offers an interactive system for setting various parameters, facilitating effective use of its wealth of functions.
- Liquid analyzers
- Monitoring process chemistry
- Water quality
- Process optimization and control
pH and ORP meters, analyzers and transmitters are used for continuous process monitoring of pH and ORP to ensure water/product quality, monitor effluent discharge, batch neutralization, pulp stock, scrubbers, cooling towers, chemical, water/wastewater treatment and many other applications.