Several important parameters to pay attention to before pH meter
The purchase of a set of industrial electrochemical instruments should include: 1. Standard substances. 2. Sensors, namely electrodes. 3. Instruments. 4. Accessories.
Comparative measurement method: use known standard substances to calibrate the instrument, and then measure the sample solution, which is the operation definition of the electrochemical instrument. Accuracy measurement: it is divided into the basic error of the electronic unit and the supporting error of the instrument. The supporting error of the instrument is determined by The accuracy of the instrument, electrode and reference material is determined. Measuring range: It is divided into the measuring range of the electronic unit and the measuring range of the electrode.
The actual measurement range of the instrument is determined by the electrode measurement range. Application fields: very wide, select the appropriate electrode according to the use environment and requirements. The heart of an electrochemical meter is the electrode. For example, pH meter, pH electrode is very important.
The classification of pH electrodes has many concepts according to different classification methods. If divided by function, there will be: low-resistance pH electrodes, high-temperature pH electrodes, strong acid pH electrodes, strong alkali pH electrodes, and voltage-resistant pH electrodes.
According to the purpose, there will be: flat pH electrode, acupuncture pH electrode, micro pH electrode. If it is a laboratory pH instrument, it is not the same.
Precautions for measuring ultrapure water with a ph meter
Because ultrapure water has its unique characteristics, it is very difficult to measure the pH value with an online pH meter. In practice, it is difficult to obtain reproducible and stable measurement results in samples of low ionic strength. Low ion samples, that is, low alkalinity, low ionic strength, or low conductivity (conductivity is generally 0.056-10) high impedance, such as deionized water. Due to the changing junction potential created in the reference junction, different pH values can result when measuring deionized water, even with a new, sealed electrode, and well corrected in buffered standard solutions.
1. Why do you need an online ph meter to measure the pH value of pure water.
In the production of pure water, measuring pure water can be used as an indicator of process contamination. When air or carbon dioxide invades the pure water production or distribution system, it will cause pH drift.
2. How to choose the online pH meter pH electrode
The more expensive double-junction electrodes offer many advantages over conventional pH electrodes, however, they do not show a particular advantage over single-junction electrodes for measuring ultrapure water. The best option is a refillable, liquid reference pH electrode made of low impedance glass. A flow reference junction has a relatively high flow rate, reducing the junction potential. A sealed electrode, usually gel-filled, has the greatest advantage of long life due to the very slow leakage rate of its reference solution. However, the faster leak rate is very suitable for ultrapure water because the pH potential can stabilize rapidly.
