Water Analyzer Operating Principle

1. ORP ORP:

Oxidation-reduction potential can help us understand what kind of oxidizing or reducing substances exist in water. It is one of the comprehensive indicators of water body. The reduction potential in water indicates the tendency of the water to release or obtain electrons, and it is in the redox reaction. The reducing agent loses electrons and the oxidizing agent gets electrons. Its reaction formula is: Red=Qx ne

Where: Red - reduced state;

Qx - oxidation state;

Ne - Electronic.

The redox potential of this system can be expressed by the Nernst equation E=E0 LnX (X=[Qx/Red])

In the formula:

n - the number of electrons participating in the reaction;

R - gas constant;

T——absolute temperature (K);

F - Faraday constant.

The redox potential of water is determined by using a noble metal (platinum) as the indicator electrode and a saturated calomel or silver/silver chloride electrode as the reference electrode to determine the oxidation-reduction potential of the electrode relative to calomel or silver/silver chloride electrode. The value is then converted to the oxidation reduction potential value relative to the standard hydrogen electrode as a result of the report.

The water that is normally in contact with the atmosphere has a redox potential of 0.3 to 0.5V. Anoxic water is 0-0.2V, and dirty water is -0.15V.

2. Temperature T:

The instrument uses a sensitive imported diode as a temperature sensor, plus a certain DC voltage, the voltage across the diode changes with the temperature change, linear in the range of 0 ~ 100 °C, this signal is displayed directly after treatment and dissolved oxygen , PH, conductivity automatic temperature compensation.

3.PH: The measurement principle of the water quality analyzer PH follows the Nernst equation:

E=E0–2.303pH

Where: R - gas constant (8.314 joules / degree mole);

T - the absolute temperature of the solution (273 t°C);

F - Faraday constant (9.65 x 104 coulombs/mole);

E0—The intercept potential of the electrode system can be seen as a constant under certain conditions;

pH - the pH of the test solution;

E - Battery electromotive force generated by the electrode system.

Measured E value will be able to measure the pH of the test solution.

4. Dissolved oxygen:

Dissolved oxygen in water analyzer means molecular oxygen dissolved in water or liquid phase. It is expressed in DO. The dissolved oxygen can reflect the extent of contamination of water by pollutants, especially organic matters. The instrument uses polarographic membrane electrode method for the determination of DO.

The measurement principle is: When a fixed polarization voltage is applied between the anode and the cathode of the electrode, the dissolved oxygen permeates in the water and the peroxorane film is reduced at the cathode to generate a diffusion current proportional to the oxygen concentration. The measured current can be used to calculate the dissolved oxygen. The amount.

5. Conductivity:

Conductivity is the ability to represent the conduction current of a solution. It is often used to indirectly estimate the total concentration of ions in water. Since conductance is the inverse of the resistance, when two electrodes (usually platinum black electrodes) are inserted into water, the two electrodes can be measured. The resistance R, according to Ohm's law, when the temperature is constant, the resistance value is proportional to the distance L (cm) of the electrode, and is inversely proportional to the cross-sectional area A of the electrode. Namely: R = ρ · L / A, because the electrode's cross-sectional area A and spacing L are fixed, so L / A is a constant, called the conductivity constant (indicated by Q), usually Q is fixed and known The measured conductance Sx can be calculated as conductivity Kx.