How do I clean the electrode of the Online pH Meter?
The online pH meter electrode should adopt a self-cleaning method. While online pH meter electrodes are widely used in the industrial field, different measurement media have different degrees of contamination, so the cleaning methods used for online pH meter electrodes are also different. For online acidity meters, if the measurement medium is relatively clean, the degree of contamination to the pH meter will be minor. The electrodes can be regularly removed for cleaning based on experience.
However, this method is increasingly used less and less in online detection. Since manual cleaning is not only labor-intensive and time-consuming, but also interrupts the measurement and affects automatic detection, automatic cleaning should be used for online pH meters. Here are 2 commonly used cleaning methods:
1. Ultrasonic cleaning
A device that can generate ultrasonic waves is installed near the pH meter probe of the acidimeter, and it emits ultrasonic waves to automatically clean the pH electrode. The intensity of the ultrasonic wave is achieved by adjusting the oscillation frequency of the ultrasonic wave. It is installed in a longitudinal manner, that is, the ultrasonic probe is installed below the electrode.
2. Solution spray cleaning
A cleaning nozzle is installed near the electrode assembly. According to the cleaning requirements, the nozzle regularly sprays water or other solutions (such as low-concentration hydrochloric acid and nitric acid solutions) to remove contaminants on the electrode by scouring or dissolving. For example, the equipped self-cleaning system uses a dilute HNO3 solution with a mass fraction of 1% as the cleaning fluid, and the injection pressure is generally higher when using water. The injection of solution is controlled by a program controller. When spraying, the online pH meter needs to be able to control the output to remain unchanged at the value before cleaning. That is, the meter output is locked at this time. The meter output remains unchanged during the cleaning period. After the pH value of the cleaning solution is stabilized, the pH meter can be used again. Detection output. In short, the combination of ultrasonic cleaning and solution jet cleaning is used to clean industrial online pH meter electrodes with good results.
The clogged pH meter electrode is caused by the blockage of the liquid junction, which can be solved by the following methods:
1. Soak the liquid junction of the pH meter electrode: Use a mixture of 10% saturated potassium chloride solution and 90% distilled water, heat to 60-70°C, immerse the pH meter electrode about 5cm, and soak for 20 minutes to 1 hour. Dissolve the crystals on the tip of the pH meter electrode.
2. Ammonia soaked pH meter electrode: When the liquid junction is blocked by silver chloride, it can be leached with concentrated ammonia water. First, clean and empty the pH meter electrode, then immerse it in ammonia water for 10 to 20 minutes, but do not let the ammonia enter the inside of the pH meter electrode. Take out the pH meter electrode, wash it with distilled water, add the internal filling liquid again, and continue using it.
3. Vacuum method: Put the hose around the liquid junction of the reference electrode, use a water flow suction pump to suck the partially filled liquid through the liquid junction, and remove mechanical obstructions.
4. Boiling liquid junction: The liquid junction of the silver-silver chloride reference electrode is immersed in boiling water for 10 to 20 seconds. In addition, the pH meter electrode should be cooled to room temperature before the next boil.
5. When the above methods are ineffective, the mechanical method of sandpaper grinding can be used to remove the blockage of the pH meter electrode. This method may cause the grinding sand particles to be stuffed into the liquid junction, causing permanent blockage.
