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ph_calibration_requirement [24/10/2018 07:00] pieter |
ph_calibration_requirement [24/10/2018 07:06] pieter |
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This process will give information on how frequently calibration/ | This process will give information on how frequently calibration/ | ||
- | The frequency that you should calibrate your pH electrode depends on many factors such as the type of your test samples, performance of electrodes, and the requirement of the accuracy. For High-Accuracy measurements (≤ ±0.02pH), the electrode should be calibrated before test every time; For general-accuracy Measurements (≥±0.1pH), | + | === Accuracy === |
+ | The frequency that you should calibrate your pH electrode depends on many factors such as the type of your test samples, performance of electrodes, and the requirement of the accuracy. For High-Accuracy measurements (≤ ±0.02pH), the electrode should be calibrated before test every time; For general-accuracy Measurements (≥±0.1pH), | ||
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+ | In the following cases, the electrode must be re-calibrated before use: | ||
* The electrode hasn’t been used for a long time or the electrode is brand new. | * The electrode hasn’t been used for a long time or the electrode is brand new. | ||
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* There is a big difference between the temperature of the test sample and the temperature of the buffer solution that is used in the last calibration. | * There is a big difference between the temperature of the test sample and the temperature of the buffer solution that is used in the last calibration. | ||
- | === Simply check === | + | === Frequency |
- | There is a simple way to quickly check if your pH meter needs a calibration at the moment. All you need to do is dip the pH probe into the calibration standard solutions such as pH 4.00 or pH 7.00, and see if the measurements have a big difference to the standard value. For most applications (if not for scientific research), if the difference is within 0.05 pH, for example the meter reads 6.97 in 7.00 solution or 4.03 in 4.00 solution, then it means the meter is in good condition and a calibration is not a must at the point. If the difference is over 0.05 pH, for example the meter reads 6.92 in 7.00 or 4.08 in 4.00, then a calibration is necessary and highly recommended before testing. | + | |
Typically, pH probes and many conductivity probes are calibrated at the start of each 8 hour shift, but this can vary depending on application. | Typically, pH probes and many conductivity probes are calibrated at the start of each 8 hour shift, but this can vary depending on application. | ||
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* The customer experience in regard to samples and application. | * The customer experience in regard to samples and application. | ||
+ | === Simply check === | ||
+ | There is a simple way to quickly check if your pH meter needs a calibration at the moment. All you need to do is dip the pH probe into the calibration standard solutions such as pH 4.00 or pH 7.00, and see if the measurements have a big difference to the standard value. For most applications (if not for scientific research), if the difference is within 0.05 pH, for example the meter reads 6.97 in 7.00 solution or 4.03 in 4.00 solution, then it means the meter is in good condition and a calibration is not a must at the point. If the difference is over 0.05 pH, for example the meter reads 6.92 in 7.00 or 4.08 in 4.00, then a calibration is necessary and highly recommended before testing. | ||
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+ | === General advice === | ||
In all cases the calibration frequency is a customer experience based decision linked to the sample type measured and the measurement frequency. Some generic advise and recommendations for use would be: | In all cases the calibration frequency is a customer experience based decision linked to the sample type measured and the measurement frequency. Some generic advise and recommendations for use would be: | ||
* Prior to using the sensor, use a check standard. | * Prior to using the sensor, use a check standard. | ||
- | * If the reading of the check standard is outside of the accuracy acceptance limits, then recalibrate | + | * If the reading of the check standard is outside of the accuracy acceptance limits, then re-calibrate |
* If the calibration is outside of the acceptance limits, then clean/ | * If the calibration is outside of the acceptance limits, then clean/ | ||