Precautions for selecting pure water pH electrode

What is the so-called (ultra) pure water pH transmitter that uses two separate electrodes for pH and reference, and adds KCL solution?

Simply put, this so-called (ultra) pure water pH transmitter is completely unoriginal! It is just a combination of two separate electrodes that have been widely used since the 1970s, with the reference electrode supplemented with KCL solution. Similar to the commonly used glass electrode 231 in the laboratory, the reference electrode 232 (232 is a supplementary KCL solution). This type of system was widely used in the past, but due to its complicated installation, a large amount of KCL leaked, crystallized, and caused corrosion of the sampling rack. What's more serious is that a large amount of KCL penetrated into pure water, and the measured pH value was not a reflection of the true state of pure water. With the advancement of technology, most manufacturers at home and abroad no longer adopt this form!

This measurement system is impossible to solve the difficulty of measuring the pH of (ultra) pure water in power plants, and is definitely affected by factors such as flow rate.

When two electrodes are separated, the resistance between them increases. In addition, pure water has poor conductivity, so the resistance between the two electrodes is more likely to change with the flow rate, resulting in a change in potential E5 and unstable measurement.

2. The reference electrode adopts the form of supplementing KCL solution. Due to a large amount of leakage of KCL solution, it pollutes the measured ultrapure water and changes the conductivity of the measured ultrapure water! This is clearly wrong!

3. Due to its pH single glass electrode, which is a traditional glass electrode in China and has only undergone changes in appearance, its performance is obviously not up to par, which will inevitably limit the service life of the electrode! Because the basic measurement of power plants is ammonia added pure water, and ammonia has the third highest corrosiveness to sensitive glass films in all media (Ba2+>S2+>NH4+), the measurement of ammonia added pure water must consider not only other factors, but also the important influence of the corrosion resistance of glass electrodes to ammonia ions! A certain instrument manufacturer claims that it uses two separate electrodes and a reference electrode with KCL solution type (ultra) pure water pH transmission unit to solve the influence of flow rate and the pollution problem of KCL leakage. It is impossible! It's against theory! It is a serious misleading to users! There are more than ten theoretical errors in the description of electrodes in its materials!