Problems with online pH meters

If the electrode is clogged, it should be cleaned promptly, 1# jonelin

First, considering the selection criteria: 1. Semiconductor electrodes are sensitive to alkaline media; at a pH of 9 or higher, errors increase； Glass electrodes are sensitive to fluoride ions; I’m a bit unclear about this ； Furthermore, the measurement range of the electrodes themselves also differs ； 2. Type: Sewage requires electrodes designed for measuring sewage, while pure, poorly conductive media have electrodes suitable for them ； All of this is related to the precipitation rate of the electrolyte, which directly affects the formation of the measuring salt bridge ； On-site situation: 1. Wiring. For ph transmitters, once a symmetric connection is set, the electrodes should also be connected in this manner ； The principle of the symmetrical connection is highly regarded: it solves the problem of equal potential. When a medium flows through a pipeline, static electricity is generated, which requires that the electrodes and transmitters be at the same potential. 2. The medium is too dirty, prone to scaling, sticking, etc ； A flushing system 3 can be considered, as well as the sampling flow rate; it is recommended to keep it between 1-2 m/s. A too high flow rate can affect the lifespan of the electrodes, and may even prevent the formation of a salt bridge. 4. The temperature should not exceed 50-60 degrees Celsius ； The nominal 120 degrees on the electrode is the instantaneous temperature during autoclaving! The higher the temperature, the faster the aging. The electrode itself is a consumable item; with the right selection, checking it every 2-3 months will show that the slope remains relatively constant ； It’s slightly worse in chemical processing environments. Domestic electrodes seem to lack sufficient quality; I’ve used domestic electrodes from Hach – the ones with thicker dedicated cables – and I had to calibrate them every 3-5 days ； After switching to the original one, there was no need to mark it for 2-3 months. Note: Water treatment industry. I prefer pH electrodes from Mettler and E+H; unfortunately, they are a bit expensive, haha. But you get what you pay for. The original poster didn’t clarify the situation at the site, nor did they specify the selection of the measurement system.

It is used in a deionized water tank; the water from that tank, after passing through a chiller, becomes cooling water used to cool materials. This water isn’t very clean either. I’m not too familiar with the selection of systems for this purpose – generally, the temperature is around 15 degrees