1.1 本试验方法包括通过颜色指示剂滴定法测定对苯二甲酸（TA）的酸值。TA产品的酸值通常在674至676 mg KOH/g之间。 1.2 在使用该方法确定测试结果的一致性时，应根据实践中的四舍五入方法对结果进行四舍五入 E29年 . 1.3 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.4 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.5 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 钽纯度的估算可以通过KOH滴定来确定。酸值作为钽纯度的指标，可用于指导钽生产的质量控制。

1.1 This test method covers the determination of acid number of terephthalic acid (TA) by color-indicator titration. Acid number of TA product is usually within 674 to 676 mg KOH/g. 1.2 In determining the conformance of the test results using this method, results shall be rounded off in accordance with the rounding-off method of Practice E29 . 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 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. 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. ====== Significance And Use ====== 5.1 An estimate of TA purity can be determined by titrating with KOH. As an index of TA purity, the acid number can be used as a guide in the quality control of TA production.