pH meter maintenance and precautions

1) Maintenance of the pH test pen and precautions:

This test pen is factory calibrated and ready for use. The following conditions must be recalibrated:

Has been used (or placed) for a long time after calibration;

Electrodes are used frequently;

Measurement accuracy is relatively high;

Do not reuse calibration buffer when making calibrations;

When the pen has a white crystal, this is a normal phenomenon, please do not be nervous, soak in water for a period of time;

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

The test pen glass electrode sensitive bulb may have small air bubbles, which will affect the normal measurement of the electrode. When using it, the electrode should be shaken, and negative air bubbles run out of the sensitive bulb;

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

If the display value is fuzzy 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:

The black plate with a switch above the pen, gently pull it out, do not break the wire, you can see four 1.5V batteries, pull out and replace;

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

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

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

To improve performance, the pH meter electrode is inserted into distilled water at least once a week for several minutes each time;

Protein precipitates (eg milk, cheese, etc.) should be immersed in a solution of pepsin and hydrochloric acid for elimination; this solution should be prepared before use. After use, the electrode should be immersed in this solution for several hours and then used as a net. The water is rinsed clean and then immersed in distilled water for several hours;

The grease film also affects the measurement of sensitive bulbs. Lee removes the thin film from the film, rinses the sensitive bulb with a 75% alcohol solution, wipes it with filter paper, rinses it well with water, and dips it into distilled water for several hours.

2) pH calibration The test pen electrode was immersed in a mixed phosphate standard buffer with a pH of 6.86 (at 25°C) and gently rocked;

Use a small screwdriver to adjust the potentiometer until the displayed value matches the pH of the standard buffer solution at ambient temperature;

The electrode is inserted into PH4.01 Phosphorus Dibasic Potassium Dioxide or pH 9.18 Borax Standard Buffer Solution;

The displayed value should be within the tolerance range compared with the pH of the buffer solution.

-. Operating steps and methods to remove the protective cover;

The electrode of the PH meter is first cleaned with distilled water, and the moisture attached to the electrode is dried with a filter paper;

Switch on the switch on the battery compartment;

Insert the meter electrode into the liquid to be measured until the liquid is immersed slightly below the "immersion line" and the condition permits to dip the solution 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;