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On-line conductivity meter calibration method

by:BOQU     2022-02-06

The online conductivity meter is equipped with different types of electrodes and is widely used in various industries such as power plants, petrochemicals, metallurgical electronics, mining, paper industry, semiconductors, medicine, food and beverage, environmental protection water treatment, and new agricultural planting.

The working principle of the online conductivity meter is the same as that of the laboratory conductivity meter. A conductivity meter can be used to calibrate the online conductivity meter, but the main difficulty of calibration is that the online conductivity meter currently used has automatic temperature compensation. function and a conductivity meter stipulate that the conductivity meter is evaluated at a specific temperature of 25, so when calibrating the online conductivity meter, the solution conductivity value that changes within a certain temperature range should be unified under the reference condition of 25. For calibration, therefore, a standard resistor should be added as a compensation element to simulate the reference condition at 25.

On-line conductivity meters mostly use four-wire electrodes, of which one pair of wires is the signal wire used to measure the conductivity value of the solution, and the other pair is the compensation element wire used to measure the temperature value of the solution.

When calibrating, connect a standard resistance to the temperature compensation end of the calibrated online conductivity meter, namely NETG and TR. The specific value is described in detail below as the reference condition of the compensation element to simulate 25. The electrode is connected to CELLY and TR. Between the cells, the AC resistance box standard device is connected, and then the calibration work such as the repeatability of the reference error indication value of the electric meter can be carried out according to the calibration regulations.

The resistance value of the standard resistor as a compensation element is the key to calibrating the online conductivity meter. Since different types of online conductivity meters have different design concepts from different manufacturers, the standard resistance value of the compensation element should be selected during calibration. bring some difficulty.

Generally, the resistance value can be read from the user manual of the instrument or the label on the circuit board of the instrument, but some instruments cannot find the resistance value of the compensation element. In this case, you can remove the connection between the lower electrode and the online conductivity meter. Insert the electrode induction head into the precision constant temperature water bath, control the water temperature at 25, and connect the two temperature compensation terminals, namely NETG and TR, to the resistance. The resistance value of the compensation element is to be connected to the reference condition of the analog 25.

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