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PH meter level accuracy with the instrument
hour：润湖 time：2011-7-10 views:
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Acidity level and accuracy of the instrument is its acidity level indicator (the power meter) division value (minimum display resolution or value), for example: indexing for the instrument known as the 0.1 0.1pH equipment; minimum display value 0.001pH instrument called the .001 instrument, and so on. The accuracy of the instrument is electric meter and electrode supporting a comprehensive testing standard error of the solution, not only with the electric meter, but also to the glass electrode and reference electrode is more relevant. From the actual requirements, the current value of indexing electric meter 0.1 ~ 0.001pH, if necessary, according to the current level of technology, can produce more sophisticated electric meter. However, due to structural and manufacturing reasons, the performance of currently used electrodes can not be completely satisfactory level. Repeatability error of the glass electrode and reference electrode junction potential stability of the solution is not better than 0.01pH. Therefore, no matter how high-resolution power meter, test the accuracy of the instrument is immune than 0.01pH. However, high-resolution instruments can choose to maximize the power meter to overcome or eliminate the impact of measurement error. As the power meter to make satisfactory accuracy has been no problem, we now have the instrument of intelligent, user-friendly, reliable, easy to operate and cost-effective in areas such as innovation and improvement. ARK Technology Development Company produced pHS-4C +, etc. "+" series model instruments is reflected in this trend. And its acidity level of the relationship between test accuracy in the acidity of national metrological verification (JJG 119-84) provides as follows: instrument level 0.2 0.1 0.02 0.01 0.001 scale value or the minimum display value (pH) 0.2 0.1 0.02 0.01 0.001 power meter indication error (pH) ± 0.1 ± 0.05 ± 0.01 ± 0.01 ± 0.002 supporting the value of the test show the total error (pH) ± 0.2 ± 0.1 ± 0.02 ± 0.02 ± 0.01 Note: The complete range of test test should be controlled within the pH3 ~ pH10. As can be seen from the table, for 0.01 less acidity, showing the value of the total error value is equal to its level of acidity for 0.01, showing the value of total error 0.02pH, for 0.001 pH meter, the total error indication can only achieve ± 0.01pH, and then need to use a pH standard material can be guaranteed. (Note: pH sub-national standard primary and secondary two, generally used is the second pH meter pH standard material.) Also need to note is that the total instrument error detection indication why the provisions of the test range of pH3 ~ pH10 it? Is due to the reference electrode liquid junction potential and solution pH on the pH3 ~ pH10 range of liquid junction potential can be stabilized at ± 0.01pH range, if 10 <pH <3, the liquid junction potential error caused by up to ± 0.07pH. Meanwhile, the glass electrode in alkaline and acidic solution also produces alkaline and acid errors error. Must provide for pH3 ~ pH10 range of detection, or it will not distinguish between the various levels of acidity showing the value of total error.
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