pH meter (acidity meter) and electrode maintenance and precautions - Solutions - Huaqiang

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1. Maintenance and precautions for PH test pen (PH electrode, pen acidity meter):

This test pen is calibrated at the factory and can be used directly. The following conditions must be recalibrated:

Used (or placed) for a long time after calibration;

The electrodes are used frequently;

Measurement accuracy requirements are relatively high;

Do not reuse calibration buffer when making corrections;

When the pen has white crystals, it is normal to be not nervous, soak it in water for a while;

Drop a few drops of the preservation solution or calibration buffer inside the pen holder. Do not use distilled water or pure water to soak or save the test pen;

There may be small bubbles in the sensitive bulb of the test glass electrode, which will affect the normal measurement of the electrode. When using, the electrode should be shaken to make the bubble run out of the sensitive bulb;

The glass electrode is easy to break, so be careful when using it;

If the displayed value is blurred or not displayed or the displayed value is much higher or lower than the true pH of the solution, the battery should be replaced.

2. How to replace the battery:

Pull the black plate with the switch on the pen and gently pull it out. Do not pull the wire off. You can see the four 1.5V batteries, and pull out and replace them.

Pay attention to battery polarity and select the same type of battery;

When the electrode is inserted into the test solution or calibration buffer, the maximum height indicated on the test pen should not be exceeded.

If the electrode is left for a long time and the sensitive bulb is exposed to the air, the electrode is dry, the response is slow and the display value is unstable. At this time, the electrode should be immersed in distilled water for several hours;

In order to improve performance, the pH meter electrode is inserted into distilled water at least once a week for several minutes;

Protein precipitates (such as milk, cheese, etc.) should be immersed in pepsin and hydrochloric acid solution for elimination; this solution is prepared before use. After use, the electrode is immersed in this solution for several hours, then rinsed with water. Clean, then immerse in distilled water for several hours;

The grease film also affects the measurement of sensitive bulbs. Li removes the film, rinses the sensitive bulbs with a 75% alcohol solution, wipes them dry with filter paper, rinses with water, and then immerses them in distilled water for several hours.

3. pH calibration. The test pen electrode is immersed in a mixed phosphate standard buffer with a pH of 6.86 (at 25 ° C) and gently shaken;

Adjust the calibration potentiometer with a small screwdriver until the displayed value matches the pH of the standard buffer solution at ambient temperature;

The electrode is inserted into potassium hydrogen phosphate dihydrogen phosphate of pH 4.01 or a standard buffer solution of borax of pH 9.18;

The displayed value should be within the tolerance of the error compared to the pH of the buffer solution.

4. Operation steps and methods remove the protective cover;

First wash the electrode of the pH meter with distilled water, and use the filter paper to absorb the moisture attached to the electrode;

Switch on the switch located on the battery compartment;

Insert the pH meter electrode into the liquid to be tested until the liquid is immersed slightly below the “immersion line”. If possible, allow the solution to immerse slightly above the “immersion line”;

Gently stir the solution until the value is stable, and read the displayed value;

After use, clean the electrode, turn off the switch, and put on the protective cover.