The basic principle of a paramagnetic oxygen analyzer is to use the paramagnetism of oxygen to analyze its concentration. Any substance will be magnetized under the action of an external magnetic field, exhibiting certain magnetic characteristics. When a substance is magnetized in an external magnetic field, an additional magnetic field is generated in the same direction as the external magnetic field, attracting the substance and exhibiting paramagnetism; On the contrary, matter is repelled and exhibits diamagnetism. Gases are magnetized in a magnetic field and exhibit paramagnetism or diamagnetism depending on the type of gas. For example, O2, NO, and NO2 are paramagnetic gases, while H2, N2, CO2, and CH4 are diamagnetic gases. The volumetric magnetic susceptibility of oxygen is much greater than that of other gases, so the paramagnetism of oxygen can be used to analyze its concentration.

The method of measuring oxygen concentration using a paramagnetic oxygen analyzer is achieved through two glass spheres (commonly known as dumbbells) filled with nitrogen gas. These two dumbbells are installed between the two magnetic poles of the enclosed chamber of the sensor, and they are fixed on a rotatable coaxial bracket. There is a reflector on the central axis of the dumbbell, which reflects the light beam emitted by the light source onto the photoelectric sensor. The oxygen in the gas to be tested will be sucked into the magnetic field, which will exert a force on the ball to rotate the dumbbell ball. The angle of the reflector will change, causing the light intensity received by the photoelectric sensor to change. In order to receive strong light signals from the photoelectric sensor, the control system drives the electromagnetic coil of the dumbbell ball with current to restore the dumbbell ball to its original position. The driving current is proportional to the oxygen concentration, thus reflecting the oxygen concentration.

We usually refer to it as a magnetic oxygen analyzer. It is generally divided into three types: thermal magnetic convection, pressure mechanical, and magnetic pressure oxygen analyzers. The magnetic properties of substances and the volumetric magnetic susceptibility of various gases. Firstly, the magnetic properties of substances. Any substance will be magnetized under the action of an external magnetic field, exhibiting certain magnetic characteristics. When a substance is magnetized in an external magnetic field, it generates an additional magnetic field. When the direction of the additional magnetic field is the same as that of the external magnetic field, the substance is attracted by the external magnetic field; When the direction of the additional magnetic field is opposite to that of the external magnetic field, it is repelled by the external magnetic field. Therefore, we usually refer to substances attracted by an external magnetic field as paramagnetic substances, or in other words, substances with paramagnetism; And the substance that is repelled by a magnetic field is called a diamagnetic substance, or in other words, the substance has diamagnetism. Gas media can also be magnetized in a magnetic field. Based on the different attraction and repulsion of gas components to the magnetic field, we also classify gases into paramagnetism and diamagnetism.