Information on the measurement and calibration of pH meters
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Why do the pH meters used by the company need to be calibrated frequently? What are the main factors that cause its variation? On the one hand, it is due to the use of a medium; on the other hand, is it related to its amplification circuit? Furthermore, is the calibration zero point of a pH meter around pH 4 or around pH 7? Willing to receive more comments from fellow sea lovers!
You need to explain where it will be used and in what industry, as there is a big difference between those
What if it is used in deoxygenated water or recycled water? What’s the difference?
We are in a bioprocessing facility; we use 7 as the zero point for calibration, as the pH value changes with temperature. Calibration also allows us to determine the quality of the pH electrodes as well as their degree of wear.
Circuit problems with pH meters are not the main reason for calibration, but rather stem from factors such as probe wear.
The sensors of pH meters are covered with glass; how could there be any wear and tear? Indeed, no signs of wear are visible! Additionally, there is the effect of temperature mentioned by friends, but it seems that modern pH meters already have built-in temperature measurement functions to apply temperature compensation. I am referring to the pH meters used by chemical plants for treating wastewater. Thank you to my friends for their support and encouragement. I hope everyone will continue the discussion.
When using sensors to measure the displacement and vibration of large rotating equipment, it is necessary to adjust the measurement distance in order to keep the amplification circuit within its linear range； By the same logic, it is possible that pH meters also face similar problems: after prolonged use, due to limitations in the electronic circuitry or the operating environment, their sensors may deviate from their linear range. Is it then necessary to perform manual calibration to bring them back into their optimal operating range?
pH meter calibration primarily involves verifying and recording the zero point and slope of the sensor (pH electrode). Zero point, the mV value at pH=7, is also known as the \"asymmetric potential,\" with a theoretical value of 0 mV. Slope is a measure that reflects the sensitivity of a sensor; the ideal value is certainly 100%, at which point the sensitivity of the corresponding pH electrode is 59.2 mV/pH. When the electrode suffers from various issues, especially contamination of the electrolyte, its performance declines, its sensitivity deviates from the ideal value, and it may even become unusable. In the use of pH meters, what is most difficult to understand is temperature compensation.
I’m very happy to hear the answer from my friend upstairs; I’ve learned a lot. Thank you! I also have a question: for a regular pH meter, what are the output signals corresponding to pH values of 1, 7, and 14? Without special consideration, just as general guidance data?