GB/T 3781.6 - 2006 focuses on the determination of acetylene carbon black visual specific volume. This standard belongs to the sixth part of the acetylene carbon black series of standards, and clearly sets out the standard process for visual specific volume measurement, covering equipment requirements, sample preparation steps and detailed measurement operations. Visual specific volume is an important performance indicator of acetylene carbon black. This standard provides a unified method for manufacturers and testing institutions to accurately determine this index, help control the mass of acetylene carbon black products, ensure that their performance meets application requirements, and promote the standardization of acetylene carbon black industry testing work.