Maintenance and calibration of industrial pH meters
(1) Where the ambient temperature differs greatly, the pH meter must be equipped with temperature compensation to eliminate the influence of the ambient temperature on the pH meter. In the winter season, strengthen the insulation of the pH meter and its pipelines to ensure that the temperature is controlled within the range of 17-21°C. The working stability of the pH meter in summer is much better than that in winter, and the temperature is controlled below 45°C.
(2) When adjusting the pH meter, the ambient temperature should be kept at 25°C. When setting the temperature compensation, it should be consistent with the temperature of the process medium.
(3) Pay more attention to the process production situation, such as abnormal production, process production shutdown, etc., it is necessary to check the pH meter in time.
① Check whether there is liquid in the flow cell. If there is no liquid, the process medium may be attached to the electrode due to dryness, and it cannot be measured when it is re-produced.
②Whether there is low temperature or crystallization in the process medium, if there is, the pH meter should be disassembled for protective treatment, and the composite glass electrode should not be placed upside down.
③The pH meter disassembled after parking must be immersed in the pH4 buffer solution containing KCl for the pH composite electrode, so that it can work on the glass bulb and the liquid junction at the same time. If the conditions are not available, the pH detection head can also be soaked in pure water for anaerobic storage, and it must not be placed in the air without protection.
(4) According to the specific situation, it is not a big problem to calibrate once a month, and calibrate as little as possible. The biggest bottleneck of the pH meter is the service life, especially the reference electrode, which is easily polluted and poisoned. If the reference electrode is damaged, the pH meter is basically scrapped.
(5) The conductivity of the measured solution affects the accuracy of the measurement. Common industrial pH meters require that the conductivity of the measured solution is not less than 50 μS/cm. In addition, it has a lot to do with the working conditions. Special attention should be paid to the working conditions containing sulfur and alkali. If necessary, let the laboratory do sampling analysis to determine the disturbance of the pH meter.
