Standard HG/T 3073-1999 specifies the use of the nitrogen adsorption method for the determination of the specific surface area of settling hydrated silica in rubber compounding agents. This method is suitable for evaluating the specific surface area of settling hydrated silica to ensure its application performance in Rubber. The standard describes in detail the experimental conditions, equipment requirements and test procedures to ensure the accuracy and reproducibility of test results. Prior to the use of this standard, the relevant safety and operating procedures should be understood and followed to ensure the safety of the laboratory environment and Reliability of data.