Interpretation of relevant measurement principles of dissolved oxygen meter

The dissolved oxygen meter is based on the electrochemical principle, i.e. redox reactions will occur on two different metal electrodes in the electrolyte solution containing oxygen;

An instrument for measuring the oxygen content in water made on the principle that the diffusion current and the concentration of oxygen in the solution have a certain relationship.

Some instruments also use polarography in voltammetry. After applying a voltage to the working electrode in the solution, the current on the polarogram generated by it is consistent with the measured substance in the solution. Concentration has a certain relationship between the production principle.

In industrial production or scientific research, if it is necessary to measure the concentration of dissolved oxygen in water or a solution, Clark\'s method is often used.

Becausethis method can directly convert the parameters to be measured into electrical signals, the test response is sensitive, and it is convenient to carry out continuous online analysis, so it is widely used.

Due to the different anode materials and electrolytes selected, Clark\'s method is divided into electrochemical polarography and Gavanic thin-film current method.

The cathode for the determination of dissolved oxygen in water by polarography is a gold or platinum electrode, and the anode is a silver electrode (reference electrode Ag /AgCl).

The electrolyte is KCl solution and the DC supply voltage is 0.65-0.85V. When the anode material is changed to lead and that the electrolyte is replaced by a solution of KOH, this is the Gavanic method.

Compared to the polarographic method, the Gavanic method has a faster oxidation reaction of the lead of the anode, so the test reading is faster and does not require biasing. It is mainly used for general laboratory analysis. Frequent maintenance should be performed.

The polarographic method must be polarized before use, but does not require frequent maintenance and is particularly suitable for online analysis of continuous processes.

The dissolved oxygen electrode can be used to measure the dissolved oxygen content in the aqueous solution of the tested sample in the field or in the laboratory.

Since dissolved oxygen is one of the main indicators of water quality, dissolved oxygen electrodes can be widely used in the measurement of oxygen content dissolved in various occasions, especially in aquaculture water, photosynthesis and respiration and field measurements.

Biochemical oxygen demand (BOD) testsare performed when assessing the ability of streams and lakes to support living organisms;

Measure aqueous solutions of samples containing organic matter as \'they become putrid, and determine the relationship between the concentration of dissolved oxygen and the temperature of the aqueous solution of the sample.

They measuring range: 0~5, 10, 20 mg/L, accuracy ±3%~±5%, response time about 30~120s. There are two categories of online continuous monitoring and laboratory instruments.

Tag: dissolved oxygen meter