Why does the display value of PH meter transmitter fluctuate so much?
The display value of online PH meter transmitter was unstable and fluctuated too much, and it failed 2 hours after the calibration of standard liquid when it was first used. The concrete phenomenon is that the PH value of the measured medium is between 6.8 and 7.2. When the PH value is 6.8, the displayed value of the transmitter changes between 5.9. When the PH value is 7.2, the displayed value of the transmitter drops at 11, and then drops to 10, and then slowly drops down. This phenomenon did not appear after replacing the new transmitter.
The problem that the display value of online PH meter transmitter fluctuates greatly is definitely rare, and there are not many problems with imported PH meters, which occasionally occur. Do you want to see if you have a new probe? Check the impedance with a new probe. Did not change the probe, check the salt bridge. * Whether to consider replacing the probe after. There may be a loose connection, so tighten the terminal.
Note: salt bridge, after the reference electrode is inserted into the measured solution, a small amount of KCl solution seeps through the porous ceramics. It is connected with the reference electrode inside and the measured solution outside, which plays the role of a bridge for electrical contact, so it is called salt bridge. The leakage speed of E salt bridge solution has a great influence on the liquid junction potential: the slow leakage speed causes the liquid junction potential to be unstable; Moreover, if the pressure of the measured solution increases and the leakage rate is slower, the measured solution may enter the reference electrode, causing the acidity meter to fail.
At pH6.8~7.2, the number of hydrogen ions changes around 4, which is very weak when converted into mv signal. If the amplifier is amplified according to this ratio and a different buffer is used, it will probably indicate -2 or 16.
Combined with the fact that the fault disappeared after you changed the transmitter, my analysis was accidental. If you didn't change the buffer at that time, the pH would probably jump, which happened. 7.2 buffer? Generally, 4.0, 6.86 (or 7.0) and 9.18 (or 9.0) are common, and the pH calibration, the buffer must be more than 2.0.
Assuming that the pH of the solution is basically unchanged, the common reasons why the displayed value of online PH meter transmitter fluctuates greatly and the readings often jump are:
1. The grounding is not good, including the pipeline between the transmitter and the electrode.
Sometimes shaking the special cable by hand or touching the metal shell of 253 will change the pH reading greatly.
&2. The electrode form is set incorrectly, which is very consistent with what you said.
Asymmetrical asymmetric connection and symmetrical symmetric connection;
3. The slope of the last calibration was too low
