Installation and Maintenance of Water Quality Analyzer

PH Meter
There are two installation methods for pH meters: flow-through and immersion types. Wastewater treatment plants generally use the immersion type. For example, in this wastewater treatment plant, the pH meter is installed in the outlet overflow channel of the oxidation ditch. The pH value here is more representative, and the water flow is stable, which does not cause significant impact on the pH meter. Regular maintenance helps ensure accurate measurements and prolong the instrument's lifespan. Attention should be paid to ensuring that the dedicated cable between the sensor and transmitter does not get wet; otherwise, the high-resistance, low-voltage signal from the electrode cannot be transmitted to the transmitter. When the electrode is not measuring, the yellow protective sleeve should be put on. It keeps the electrode moist, which helps extend its lifespan. About every month, the electrode should be cleaned: first wash off attachments with a gentle water flow, then soak the electrode in a cleaning solution for a period of time, and finally rinse with clean water. The sensor bracket should also be cleaned. After each cleaning, calibration should be performed with a buffer solution. Among domestically produced pH calibration solutions, the one with pH=4 is acceptable, but that with pH=7 is not accurate enough and can affect the calibration result. Therefore, it is best to use the calibration solution provided by the manufacturer. Manufacturers generally provide two standard solutions: one with pH=7 for zero-point calibration of the instrument, and one with pH=4 for calibrating the signal output slope of the instrument.

Dissolved Oxygen Meter
Dissolved oxygen meters generally use immersion installation. It is important to use the original manufacturer's installation bracket. The bracket provided by the manufacturer is made of stainless steel with a plastic chain. By adjusting the chain length, the sensor's immersion depth can be changed, and the guide tube on the bracket ensures that the sensor remains vertical. The bracket is specially designed to transmit the water surface fluctuations to the immersion tube, causing slight vibration in the tube. This produces an additional cleaning effect on the probe surface. Some users, to reduce costs, make their own installation brackets, which often results in poor sealing between the immersion tube and the sensor. Wastewater can seep in, immersing the connection between the dedicated cable and the sensor in water for prolonged periods, potentially damaging the sensor. Some even install the sensor directly in the water without a bracket, which creates significant tension between the sensor and cable, making the sensor more prone to damage. The dissolved oxygen probe should be gently cleaned with water every week. If the membrane is damaged, it should be replaced promptly, and the electrolyte should also be replaced if contaminated. Components such as H2S, NH3, benzene, or phenol in wastewater can harm the membrane. In such cases, the membrane must be frequently replaced. The condition of the probe electrode can be judged by color: the reference electrode should be black-gray, the cathode (gold electrode) should be yellow, and the counter electrode must be shiny; otherwise, cleaning or regeneration is required. With China placing increasing emphasis on water resource protection, wastewater treatment has become more important, and the associated detection instruments for the treatment process are indispensable. As the most important instrument in the wastewater treatment industry, water quality analyzers, in addition to correct selection and installation, require regular maintenance and calibration, which are crucial for the instrument to truly function effectively [2]. ...