At the anode outlet after starting up with the newly installed ion exchange membrane, the tube does not change color
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This post was last edited by sunjl1981 on 2013-1-6 at 20:29. At the anode outlet after the newly installed ion exchange membrane came online, all the other pipes turned yellow quite quickly, indicating the generation of chlorine gas; only the pipe with the new membrane remained unchanged in color, staying white, and it took a long time before it turned yellow as well. What could be the reason for this? # + + .
Our ion membrane is from little Japan
There are no pinholes. . . . . . This is a new membrane, and the leak test showed no leaks
Therefore, it is necessary to check the cell slot voltage, chlorine purity, as well as the hydrogen and oxygen content in chlorine in order to determine whether there is a membrane leak; sometimes pinhole testing for leak detection is not very accurate.
Hesitantly asking: Is it a problem if the anode outlet turns yellow? :o
There should be no problem; chlorine itself is yellow-green in color. If it turns red or purplish-red, that is abnormal, and it is usually caused by a membrane leak that leads to coating corrosion and subsequent reactions.
There should be no problem with that. We also experience this phenomenon, which is related to the hose to some extent, as well as to the membrane efficiency.
I asked a similar question before, but no one answered it. It’s certain that the membrane has no pinholes; it’s probably related to the new membrane, but I’m not sure of the exact reason.
I personally think it is due to the new membrane, because it takes some time for the membrane channels to open when the new membrane is put into operation. This period is a bit longer than it takes to reopen the channel with the old film.
As mentioned above, when the new membrane is put into operation, it takes some time and certain conditions for the membrane channels to open: 1. In Japanese manufacturing processes, brine and the catholyte generally do not exchange heat before entering the tank； 2. The new condition for opening the channel is that the saltwater concentration is around 250 g/l ； 3. Water channels exist in the membranes in Japan; initially, they are formed at the expense of the core material, and under electrolytic conditions they dissolve to form water channels. This post was last edited by yzhms on 2008-1-20 17:56.]
I don’t quite understand; it doesn’t seem to be explained clearly. The so-called channels are water channels; is this related to the release of chlorine? My personal impression is that in an electrolytic cell with a new membrane, it is relatively difficult for chlorine to escape from the surface of the membrane at first, so there is a delay; however, in my observation, this delay is not long-lasting. Anyway, it’s hard to explain clearly; I’ll ask Expert J next time
The discoloration at the anode outlet occurs relatively late, indicating that the membrane has relatively small pinholes. This cannot be detected during membrane leak testing, as Asahi Kasei requires a leakage rate of more than 10 l/h before replacing the membrane during such tests. However, from our actual tests, it turns out that even new membranes have a certain level of leakage. Therefore, whether it is a membrane leak must be determined in conjunction with the cell slot voltage.
There is a general consensus regarding Japanese membranes: these membranes have no pinholes in the bubble test, but pinholes become apparent as soon as the vehicle is driven.
We have also encountered this problem: even after replacing the membrane twice with new ones, the same issue arose. We tested the new ion exchange membranes for leaks before installing them, and no pinholes were found; however, their coloring time was different from that of the other membranes, being slower. It can be determined that the problem lies with the membrane itself, as membranes from other batches did not exhibit this issue. According to experts from Asahi Kasei, different batches of membranes have varying layers of carboxylic acids and sulfonic acids on their anode and cathode sides, so a membrane from a particular batch may have inherent defects
It should be related to the new membrane itself; check the chlorine and hydrogen content again
How long is this period of time exactly? At what level does the current rise? Generally, when the current rises to 3,000, it should change color completely; if it takes a bit longer, it’s probably not by more than a few minutes. This could be related to the new membrane, or it might be because a new outlet tube has been installed
During low-load testing, as long as the hydrogen content in chlorine is within normal levels and the cell voltage is normal, and the anode does not change color at 2.7 KA, it is still possible to increase the voltage to 4 KA and observe further.
When the current rises to over 80%, it doesn’t change color; basically, no color change will occur, and in that case one has to stop the machine and replace the membrane.
The newly installed membrane may also leak, so it is recommended to perform a leak test on the membrane when the vehicle is parked. Apart from the quality of installation, the most likely reason for leakage in the new membrane is a defect in the cell, such as burrs; if the membrane does leak, the cell should be carefully inspected when replacing it. Furthermore, I disagree with what moderator haining said; generally, the color does not change even when the current rises to 3KA at the anode outlet. It is best to stop the machine for inspection, as there is a high possibility of membrane leakage in such cases, and it is very dangerous. Last edited by sister on 2009-3-6 15:02]
What my sister upstairs said is right – the membrane will definitely leak. But considering we’ve spent a whole day working hard to increase the current level, we’ll avoid replacing it if possible. I encountered this a few times: during membrane leak testing, a slight leak could be detected, but it wasn’t severe enough to warrant replacing the membrane. However, when the current was increased, the tube didn’t change color. At that time (the first time I saw it), we were hesitant about whether to stop operations; it wasn’t until 6KA that the tube changed color ； The longest wait was until 9KA could change color as well: lol. With some experience now, I’m not in a hurry; I wait until it really can no longer change color before deciding to replace the membrane.