The standard "ISO 5789-1979 Fluorocarbons for Industrial Use, Determination of Non-Volatile Residues" specifies a method for determining the content of non-volatile residues in fluorocarbons for industrial use. This test method is applicable to various fluorocarbon products used in industrial production. The purity and mass of the product are evaluated by mass determination of the remaining material after the sample is heated and evaporated. This standard provides a detailed description of the test equipment, operation steps and calculation methods to ensure the accuracy and repeatability of the determination results. It provides a unified technical basis for the quality control and performance evaluation of fluorocarbons, helping to meet the requirements of industrial production and application, while promoting the conformity of product mass and industry standardization.