pH readings swings during analysis

pH readings could swing up to 0.15 or 0.20 before the addition of reagent begins.

If the readings show swings greater than 0.20, e.g. it jumps from 8.05 to 8.33 suddenly, it means that the pH readings are not good, and the analysis will probably finish earlier than it should or later. As a result it will probably give an incorrect KH result.

Pre-checks:

• Make sure that the probe is connected and in its position in the autoBalance.
• Make sure that the magnet stirrer spins correctly, although it is important that the stirer magnet spins, it should not affect to the pH readings before the reagent begins to be added.
• The led wire is located between the wall of the autoBalance and the probe, not around the probe on the outside.

When reagent is added it is perfectly possible and normal to see jumps greater than 0.2 and more and decreasing. It is also possible for them to be punctually increasing.

Possible solutions:

• Clean the probe. After some use, adhesions are deposited on the electrode. To clean the probe it is recommended to put it under tap water and use a paper towel or soft cloth to remove the adhesions. Once cleaned, it is recommended to calibrate the probe again.
• Clean and dry the probe connector. If the probe connectors to the autoBalance are dirty or wet they will transmit a wrong voltage, and consequently the readings will be incorrect. Clean and dry both connectors thoroughly. Once clean and dry, it is recommended to calibrate the probe.
• Incorrect calibration. If for whatever reason the probe has been calibrated incorrectly, with the same calibration liquid the pH4 and pH7, with contaminated liquids, or any other incidence, the readings will be incorrect and could oscillate. Within the Info System section in configuration, we will find the calibration voltages V4 and V7, the value of v4 should be around 2.0. The v7 value should be around 1.5, and above all the difference should be around 0.5. If not, recalibrate the probe.
  • V4 normal: 1.9 – 2.1
  • V7 normal: 1.4 – 1.6
  • Difference between V4 and V7: 0.44 – 0.56
• Other problems. If the readings are incorrect after applying all possible solutions and after having done the checks, it could be a software or hardware problem. If possible, try another probe, even if it is an old probe or from another manufacturer, to rule out a probe problem. Remember that the probes are consumable material, so they must be answered periodically. You can also try a reset, an analysis memory erase and a firmware reinstallation. If you suspect that it is a hardware problem, please contact Xepta’s technical service.