GB/T 261-2008 stipulates that the flash point is determined by the Binsky-Martin closed cup method. This method is suitable for many liquids, including petroleum products and related chemicals. The principle is that in a specific closed cup, the sample is uniformly heated, and the flash point is determined by a standard flame detection at regular times. The standard specifies the technical specifications of the Binsky-Martin closed cup measuring instrument, such as cup material, dimensional accuracy, etc. Detailed sample preparation work, such as sample collection, temperature equilibrating treatment. Key operations such as heating rate and flame detection timing are also standardized, so as to accurately determine the liquid flash point and provide core data for evaluating the risk of liquid fire.