Selection of measuring instruments for pH values around 13
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The chemical processing unit is equipped with a pH meter for online analysis; the required value for this meter is not less than 12.5. The pH level of the liquid being measured (mainly softened water containing a small amount of AlCl3 particles) is around 13. The operating pressure is 12 barg, and the operating temperature is 60°C. Imported pH probes are currently in use at the site, and the following problems have arisen: probes that are new or calibrated with neutral water give accurate readings; however, as time goes by, their readings start to deviate from the pH of the liquid being measured, with the deviation being downward. For example, the offline measurement shows a value of 12.8, while the online reading is 12.3. The online probe was removed and calibrated using standard solutions at pH=5 and pH=8.5, with accurate readings from the probe. After reinstalling the calibrated probe, it was able to provide accurate readings for 2 days, after which the issue of low readings occurred. We are developing new types of online pH probes that can be used in such environments; we ask our colleagues at sea to provide information on the optimization of existing solutions as well as details regarding these new online pH probes. Thank you!
I don’t know what kind of electrodes you use. Exposing a glass electrode to alkaline solutions for an extended period has an impact on its hydration layer; it generally needs to be calibrated once a day during continuous use.
This is caused by a phenomenon known as \"alkaline deviation\" that occurs during pH measurement. It’s no problem. Using a pH meter to measure strong alkaline solutions is no longer a very appropriate method; if there are other analytical methods available, those should be used whenever possible.
I agree with what was said on the second floor. Also, I wonder if the medium used for measurement might cause deposits to form on the probe.
Industrial pH electrodes can be used, such as antimony electrodes, etc