Oxygen index refers to the minimum oxygen concentration percentage required for the combustion of a substance at a specific temperature and oxygen concentration. This index is generally used to evaluate the flame retardancy of materials, and it is also an important index in industrial production and architectural design. The higher the oxygen index, the better the flame retardancy of the material.

Oxygen index is widely used in all walks of life, especially in the construction and electronics industries. Printed circuit boards, insulating materials and electrical accessories in the electronic industry must have a high oxygen index before they can be approved for use. In the construction industry, the oxygen index is also very important for wall fire protection layer, wood and plastic building materials.

The conventional oxygen index test method is to put the material into a fixed container and add a certain amount of oxygen, and then give it to the ignition source to quickly record the minimum oxygen concentration of successful ignition. However, with the continuous development and progress of fire prevention technology, there is also a calculation method based on mathematical model to evaluate oxygen index. These new testing methods are favored by people more and more, and gradually become the research focus of oxygen index testing.