Calibration and calibration precautions of pyrometer PH meter

The pyrometer PH meter has a wide range of applications and various types. Therefore, the instrument should be calibrated according to the time period specified in the manual when measuring, and the calibration methods are all two-point calibration methods.

Choose two standard buffers: one is pH7 standard buffer, the second is pH9 standard buffer or pH4 standard buffer. First use the pH7 standard buffer to position the meter, and then select the second standard buffer according to the acidity and alkalinity of the solution to be tested. If the solution to be tested is acidic, use the pH4 standard buffer; if the test solution is alkaline, use the pH9 standard buffer. If it is a manually adjusted pH meter, the operation should be repeated several times between the two standard buffer solutions until the zero point and positioning (slope) knobs are no longer adjusted, and the high-temperature pH meter can accurately display the pH values u200bu200bof the two standard buffer solutions. The calibration process is complete.

The temperature of the standard buffer solution should be as close as possible to the temperature of the tested solution.

The positioning standard buffer solution should be as close as possible to the pH value of the measured solution. Or during two-point calibration, try to keep the pH of the tested solution within the interval of two standard buffer solutions.

After calibration, the electrode immersed in the standard buffer solution should be specially rinsed with water. Due to the buffering effect of the buffer solution, the measurement error will be caused after the solution is brought into the test solution.

Afterward, the zero point and positioning knobs should not be moved during the measurement process. If it is an intelligent pH meter, there is no need to repeat the adjustment, because the pH value of several standard buffers is stored in it for selection, and it can be actively identified and actively calibrated. But pay attention to the accuracy of standard buffer selection and preparation. The intelligent 0.01-level pH meter generally has three to five standardized buffer pH values u200bu200bin its memory,

Secondly, pay special attention to the temperature of the solution to be tested before calibration. In order to correctly select the standard buffer solution, and adjust the temperature compensation knob on the meter panel to make it the same temperature as the solution to be measured. At different temperatures, the pH value of the standard buffer solution is different.

After the calibration work is completed, the pyrometer that is frequently used generally does not need to be re-calibrated within 48 hours. If one of the following situations is encountered, the instrument needs to be calibrated from the beginning:

(1) The positioning or slope conditioner is incorrectly moved;

(2) After measuring over acid (pH<2) or="" over="" alkaline="" ph="">12) solution;

(3) After changing the electrode;

(4) When there is a big difference between the solution temperature and the calibration temperature.

(5) The electrode is exposed in the air for too long, such as more than half an hour.

(6) When the pH value of the measured solution is not in the middle of the selected solution during two-point calibration, and it is far away from 7pH.

When recording the pH value of the measured solution, the temperature value of the measured solution should be recorded together. Because of the deviation from the temperature value, the pH value is simply meaningless. Although most pH meters have the function of temperature compensation, they only compensate the response of the electrode, that is to say, they are only half-compensated, and the temperature of the measured solution is not compensated together, that is, full compensation.