The Limiting Oxygen Index (LOI) test method is a common method used to evaluate the combustion characteristics of materials. It measures the concentration of oxygen in a gas mixture needed to sustain combustion of a given material. The test method helps to determine the burning properties and flammability of a material.

In recent years, advances in limiting oxygen index test methods have focused on the following areas:

1. Standardization and norms: Various industries and countries have developed standards and norms to ensure consistency and comparability of limiting oxygen index tests. These standards include ISO 4589-2, ASTM D2863, GB/T 2406, etc., which specify the detailed steps and requirements of the test methods.

2. Automation and digitization: To improve the accuracy and efficiency of testing, many laboratories have adopted automation and digitization technologies. Automated systems can control parameters such as gas flow, temperature, and pressure, and record data for analysis and reporting. In addition, some laboratories use computer simulation and modeling techniques to predict and optimize the combustion performance of materials.

3. Precision Instruments and Sensors: In recent years, significant improvements in the accuracy and sensitivity of instruments and sensors have allowed for more accurate measurements of the limiting oxygen index. Advanced oxygen analyzers, flow meters, and temperature control equipment can provide more reliable test results.

4. New materials and applications: As technology advances, more and more new materials and applications have emerged. These materials may have different combustion properties and requirements, so the limiting oxygen index test methods need to be optimized accordingly. At the same time, some special applications, such as aerospace and electronics, have more stringent requirements for limiting oxygen index testing, requiring more accurate test methods and equipment.

Overall, limiting oxygen index test methods have been further developed in terms of standardization, automation, accuracy and adaptation to new materials and applications. These advances have helped to improve the accuracy, reliability and efficiency of testing and to meet changing requirements.