1.1 本试验方法包括使用玻璃、锑或离子选择场效应晶体管（ISFET）电极作为传感器，通过电测量法连续测定水的pH值。 1.2 该测试方法不包括电导率小于100μS/cm的样品的测量。参考测试方法 第512页 . 1.3 本试验方法不包括pH的实验室或取样测量。参考试验方法 第1293天 . 1.4 以国际单位制表示的数值应视为标准。 本标准不包括其他计量单位。 1.5 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者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。 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 ====意义和用途====== 5.1 pH是衡量水中氢离子活性的指标。它是影响水的腐蚀性和结垢财产、水中生物寿命以及化学过程控制的许多应用的一个主要参数。因此，在水净化、使用和废物处理过程中，它在释放到环境中之前是很重要的。 5.2 在线pH测量优于实验室测量，以获得实时、连续的值，用于自动控制和监测。

1.1 This test method covers the continuous determination of pH of water by electrometric measurement using the glass, the antimony or the ion-selective field-effect transistor (ISFET) electrode as the sensor. 1.2 This test method does not cover measurement of samples with less than 100 μS/cm conductivity. Refer to Test Method D5128 . 1.3 This test method does not cover laboratory or grab sample measurement of pH. Refer to Test Method D1293 . 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 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. 1.6 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 pH is a measure of the hydrogen ion activity in water. It is a major parameter affecting the corrosivity and scaling properties of water, biological life in water and many applications of chemical process control. It is therefore important in water purification, use and waste treatment before release to the environment. 5.2 On-line pH measurement is preferred over laboratory measurement to obtain real time, continuous values for automatic control and monitoring purposes.