How to measure the pH of an enamel kettle
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This post was last edited by k154nlw77956k on 2022-2-17 at 10:51. The side of the mixing tank cannot have any openings; there is only one discharge hole at the bottom. There is an agitator inside. To measure the pH from the top down, the probe needs to be inserted about 3.5 meters deep to obtain an accurate reading. As shown in the diagram, I plan to first insert a DN125 pipe lined with 304 material and covered with PTFE, and then insert the pH probe into that pipe； Another idea is to add a tee at the discharge port for measurement; I’m not sure if that will work.
It would be best if you could provide the approximate material composition, so that we can discuss the specific technical details. Additionally, your requirement for a measurement accuracy of 0.05 pH is somewhat high; this is because your material remains at a pH level of 3 or lower for most of the time, which is in a strongly acidic range, and as a result the deviation of the pH electrode may exceed 0.1 pH. Is the stirring speed in the reactor very high? What are the corrosive solid materials involved? Is explosion protection required at the site? Do the electrodes need to be cleaned during operation intervals?
What I really want to discuss at the moment is the method of top-insertion measurement – how to safely determine the pH value. It involves online plugging and unplugging, and the device must be explosion-proof. It’s a concentrate from the biopharmaceutical industry, a mixture of solid and liquid substances, with not too much solid content; the customer isn’t sure exactly what it is.
Any type of online analyzer, especially one that is not used in conventional standard applications, is nonsense if specific environmental conditions are not taken into account. Let the users solve it on their own; they can bear the consequences of whether the result is good or not
In sections where pH adjustment is required, reliance on mixing within the container itself is not sufficient; an outlet pump is also needed to create circulation and enhance mixing, in order to obtain an accurate pH value as quickly as possible. Otherwise, the local mixing will be uneven, and the pH value will remain unstable even halfway through the discharge process. Therefore, it is generally installed at the pump outlet of the bottom discharge port, or on the pump’s circulation pipeline; this way, if the pH value is not within the acceptable range, the valve leading to the downstream section can be closed automatically, while the circulation pipeline remains open to protect the pump.
In other words, when the reactor is used to adjust the pH, the discharge pump must be turned on, and the pipes behind the pump should be arranged in pairs of two; one of these pipes leads back to the feed inlet of the reactor, and it is on this pipe that our pH meter is usually installed. Is that how it should be understood?
Yes, there is a section of pipe after the pump; one branch leads back to the tank while the other goes downstream. A pH meter can be installed on that outlet pipe to measure the pH value, and if it is not within the acceptable range, a interlock mechanism will be triggered to close the valve leading downstream.
Neither top insertion nor bottom insertion is likely to yield good results; it should be possible to insert the pH probe through a circulating pipeline, so as to achieve closed-loop control.