1, pen for maintenance and attention:
Pen type pH meter factory, has been calibrated, can be used directly, the following conditions shall be re calibrated:
Pen type pH meter after calibration has been used for a long time (or place);
The use of PH electrodes is especially frequent.
The precision of measurement is high.
Do pen for correction, do not repeat using pH correction buffer;
When the pH pen has white crystals, this is a normal phenomenon, do not be nervous, soak for a period of time with clear water;
A few drops of liquid storage or pH correction buffer in the cap, do not use distilled water or pure water to soak or save the pen for;
Pen type pH glass electrode for sensitive bulb may have small bubbles, it will affect the normal measurement of pH electrodes should be used to shake the electrode, the bubble ran out of sensitive bulb;
Glass pH electrode is easy to break and need to be careful when using.
The battery should be replaced when the display value is fuzzy or not display or display value is higher or lower than the real pH value of the solution.
2, to replace the pen for battery:
Black plate pen for above a switch, gently pull out, do not pull wires, can see 4 1.5V batteries, pulled out and replaced;
Note the pen for the polarity of the battery and the selection of the same type of battery;
The pH electrode is inserted into the sample solution or correction buffer, can not exceed the maximum height of the test pen marked.
If the pH electrode is placed for a long time and the sensitive bulb is exposed to the air, it will slow down the response and show the value is unstable due to the drying of electrodes. At this time, electrodes should be immersed in distilled water for several hours.
In order to improve the performance, at least once a week to the pH electrode is inserted into the distilled water every few minutes;
Protein precipitates (such as the measurement of milk \ \ cheese to eliminate) treatment in pepsin and hydrochloric acid solution; the solution before use ready, after use, the electrode immersed in this solution for several hours, and then rinse with water, then immersed in distilled water for several hours;
The oil film also affects the measurement of the sensitive bulb. Li removes the thin film, rinses the sensitive bulb with 75% alcohol solution, filters it dry and rinses it with water, then immerses in distilled water for several hours.
PH, for the calibration of 3 pen
The pen type pH meter electrode immersed in pH 6.86 (25 DEG C) mixed phosphate buffer solution, and gently shake;
Adjust the correction potentiometer with a small screwdriver until the display value is in accordance with the pH value of the standard buffer solution at ambient temperature.
The pH electrode was inserted into the PH4.01 standard buffer solution of potassium hydrogen potassium two formate or PH9.18 in borax.
The display value should be within the allowable range of error compared to the pH value of the buffer solution.
Operation steps and methods
Take down the protective cover;
The first electrode for cleaning the distilled water, and the water drain on the electrode will be attached with the filter paper;
Switch on the switch on the battery bin.
The pH electrode inserted into the measured liquid, until the liquid dipped slightly below the "immersion line", the conditions allow, can make the solution to slightly higher than the "immersion line" position;
After gently stirring the solution to be stable, read the display value.
After use, clean the pH electrode, turn off the switch, and cover the protective sleeve.