E-mail: michael@shboqu.com   |   Expert in Water Quality Measurement and Water Treatment Project

Brief introduction of online ph meter

by:BOQU     2023-04-10
Brief measurement principle: The instrument (electronic unit) is composed of signal measurement, calculation, display, network communication and panel instructions. pH and temperature transmission impedance conversion, pH becomes 459.16mV/pH (25 ℃) low resistance signal; NTC is converted into a voltage signal. The instrument is matched with the pH electrode of the sensor to monitor the pH value of the solution pH. The sensor is a battery composed of a pH glass electrode and a calomel (or Ag/AgCl) reference electrode, which is related to the pH value of the solution according to the Nernst equation. The potential difference: Ex=Eo+SpH. The potential difference is amplified by the pre-amplification stage with high input impedance, and the thermal sensor sends out a signal corresponding to the temperature value. After the two signals are amplified, they are converted by A/D, and calculated by a single-chip microprocessor through the I/O interface chip. will be displayed prominently on the display. Electrical structure principle: (1) Internal reference electrode: silver/silver chloride electrode, the main function is to lead out the electric potential, which requires stable potential and small temperature coefficient. (2) Internal reference solution: an internal reference solution with a zero potential of 7pH. The glass battery and the reference battery constitute the pH value at which the zero potential of the battery is established, which mainly depends on the pH value of the internal reference solution and the concentration of chloride ions. Electric slope: The slope of glass electricity is theoretically 59.16mv at 25°C, that is, every time the solution changes a pH value, the glass electricity will produce a potential change of 59.16mv. But in fact, all glass electricity cannot reach the theoretical value. Generally, the electric slope is more than 98% (percentage slope) of the theoretical value. In addition, the mv difference corresponding to each unit PH value at different temperatures has a certain change. When the online PH meter is installed, the electricity needs to be measured in a sealed environment to obtain an accurate value, otherwise the contact between the medium and air can affect its measurement results. . Flow-through installation is required for measurement in a sealed environment, and the supporting installation of the flow-through cell is generally the way of water inflow from the bottom and drainage from the top. During the measurement process, ensure that the instrument is always isolated from the outside world to prevent the medium from contacting with the outside air, which will affect the accuracy of the measurement data. The online pH meter has the characteristics of Chinese (English) display, Chinese (English) menu operation, full intelligence, multi-function, high measurement performance, and strong environmental adaptability. This meter is a highly intelligent online continuous monitor, which consists of two parts: a sensor and a secondary meter. It can be equipped with three-composite or two-compound power to meet various usage places. It can be widely used in the continuous monitoring of pH value in solutions such as thermal power, chemical fertilizer, metallurgy, environmental protection, pharmaceutical, biochemical, food and tap water. Precautions for the use of online pH meter: Please follow the operating procedures and precautions in this manual when using it. If you find that the instrument is working abnormally or damaged during use, please contact the dealer, and do not repair it by yourself. In order to make the measurement more accurate, the instrument must be calibrated frequently with electricity. Please preheat the instrument for 30 minutes before performing the calibration work.
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