GB/T 8333-2022 specifies the test method for the vertical burning characteristics of rigid cellular plastics, which is applicable to evaluating the small-scale burning behavior of such materials under laboratory conditions. It is not suitable for materials that melt or drip during combustion. The standard assesses the burning performance of materials by vertically fixing the specimen, igniting its lower end with a specified flame, and measuring parameters such as burning time, flame height, and percentage of residual mass. The test requires instruments such as a Bunsen burner, timing devices, a balance with an accuracy of 0.01 g, and a fume hood. It strictly controls flame temperature and combustion conditions, providing a unified technical basis for the research and development, quality control, and safety selection of rigid cellular plastics in related applications.