Application of online pH meter in ultrapure water
It not only removes the conductive medium in the water almost completely, but also removes the undissociated colloidal substances, gases and organic matter in the water to a very low level. The resistivity is greater than 18MΩ*cm, or close to the limit of 18.3MΩ*cm.
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 with low ionic strength. Low ionic samples, that is, low alkalinity, low ionic strength, or low conductivity (conductivity is generally 0.056-10) and high impedance, such as deionized water. Due to the varying junction potential produced in the reference junction, different pH values will be produced when measuring deionized water, even with new, sealed electrodes that are well calibrated in buffered standard solutions.
1. Why is it necessary to use an online pH meter to measure the pH value of pure water.
During the production of pure water, measuring pure water can serve as an indicator of process contamination. When air or carbon dioxide intrudes into a pure water production or distribution system, it will cause a pH drift.
2. How to choose online pH meter pH electrode
The extension bridge electrode is refillable and specially made of low-resistance glass. A flowing reference junction has a relatively high flow rate, which reduces the junction potential. The greatest advantage of a sealed electrode, usually gel-filled, is long life due to its very slow leakage rate of reference solution. However, faster leak rates are ideal for ultrapure water because the pH potential can stabilize quickly.
