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This standard is not equivalent to ISO9277:1995 "Determination of Specific Surface Area of Solid Substances by Gas Adsorption BET Method". The main additions, deletions, and modifications to this standard relative to ISO9277:1995 are as follows:

Added content: the measurement range covers nano powder; Added six terms in section 3.1, including equilibrium adsorption pressure, saturated vapor pressure, relative pressure, adsorption capacity, molecular cross-sectional area, and monolayer amount; Section 5.2 has added scales, Dewar flasks, sample containers, and vapor pressure thermometers to the auxiliary equipment; Added conversion formulas for particle size and specific surface area in section 8.5.

Reduced content: The control instrument parts in Figures 1, 3, and 4 of the international standard, as well as the adsorption isotherms in Figures 5 and 6, have been removed; Appendix A and Appendix B in international standards have been cancelled.

Revised content: Chapter 8 provides specific formulas for calculating the dead space factor in the volumetric method, relative pressure in the chromatographic method, and adsorption capacity for three measurement methods, while the international standard only states that "ordinary gas state equations should be used to determine".

Drafting of the standard: This standard was proposed by the China Nonferrous Metals Industry Association. This standard is under the jurisdiction of the National Nonferrous Metals Standardization Technical Committee (TC243/SC4). This standard was drafted by the Iron and Steel Research Institute. The main drafters of this standard are Wei Yun, Li Zhongquan, Wang Junqin, and Zhang Xianming.

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