【国外标准】 Standard Test Methods for Precipitated Silica—Surface Area by Single Point B.E.T. Nitrogen Adsorption

4.1 These test methods measure the approximate surface area of precipitated hydrated silicas that is available to the nitrogen molecule using an approximation of the B.E.T. method. While the multi-point version of the B.E.T. method is generally accepted as being less prone to errors arising from the varying surface properties of individual samples, the single-point approximation is often adequate due to the shorter time per test and relative simplicity of the instrumentation needed. Quality control applications and comparative tests on near-identical samples of close chemical and micro-structural composition are likely to be the applications of greatest value.1.1 These test methods cover a procedure to measure the surface area of precipitated hydrated silicas by, a single point approximation of the Brunauer, Emmett, and Teller (B.E.T.)2 theory of multilayer gas adsorption. These test methods specify the sample preparation and treatment, instrument calibrations, required accuracy and precision of experimental data, and calculations of the surface area results from the obtained data.1.2 These test methods are used to determine the single point nitrogen surface areas in the range of 100 to 500 m2/g.1.3 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. The minimum safety equipment should include protective gloves, sturdy eye and face protection.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.