1.1 本试验方法涵盖未使用有机传热流体热稳定性的测定。该程序适用于在高于和低于其沸点（除非另有说明，否则指正文中的正常沸点）的温度下用于传热的流体。它适用于最大整体工作温度在260℃之间的流体 摄氏度（500摄氏度） °F）和454 °C（850 °F）。该程序不得用于测试高于临界温度的流体。在本试验方法中，挥发性分解产物在试验期间与流体持续接触。该测试方法不会测量热稳定性阈值（挥发油碎片开始形成的温度），而是指示在指定温度和测试期间发生的大块碎片。 因为在260以上的温度下可能会发生高压气体的分解和生成 摄氏度（500摄氏度） °F），请勿将本试验方法用于在这些温度下产生高压气体的含水流体或其他流体。 1.2 DIN标准51528和GB/T 23800涵盖了与本试验方法类似的其他试验方法。 1.3 尚未确定该试验方法对硅氧烷基传热液的适用性。 1.4 以国际单位制表示的数值应视为标准值。括号中给出的值仅供参考。 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。 有关特定警告声明，请参阅 7.2 , 8.8 , 8.9 和 8.10 . 1.6 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 当接触到足够高的温度时，传热流体会降解。降解量随着温度的升高或暴露时间的增加而增加，或两者同时增加。由于反应和重排，可以形成降解产物。降解产物包括高沸点和低沸点组分、气体分解产物和不能蒸发的产物。 产生的降解产物的类型和含量将改变传热流体的性能特征。为了评估热稳定性，有必要定量测定热应力传热流体中高沸点和低沸点组分以及气体分解产物和不能蒸发的物质的质量百分比。 5.2 本试验方法区分了在试验条件下，在没有氧气和水的情况下，有机传热流体在高温下的相对稳定性。 5.3 用户应自行确定本试验方法的结果是否与现场性能相关。工业厂房中的传热流体暴露于各种其他影响变量。 与电厂材料、杂质、受损流动条件下的热量积聚、传热流体回路中的温度分布以及其他因素的相互作用也可能导致传热流体发生变化。该试验方法提供了传热流体相对热稳定性的指示，并可被视为流体选择决策过程中的一个因素。 5.4 结果的准确性在很大程度上取决于遵循测试条件的程度。 5.5 本试验方法不具备量化或以其他方式评估非应力流体沸腾范围内热分解产物的形成和性质的能力。无应力流体沸腾范围内的分解产物可能占总热降解的很大一部分。

1.1 This test method covers the determination of the thermal stability of unused organic heat transfer fluids. The procedure is applicable to fluids used for the transfer of heat at temperatures both above and below their boiling point (refers to normal boiling point throughout the text unless otherwise stated). It is applicable to fluids with maximum bulk operating temperature between 260 °C (500 °F) and 454 °C (850 °F). The procedure shall not be used to test a fluid above its critical temperature. In this test method, the volatile decomposition products are in continuous contact with the fluid during the test. This test method will not measure the thermal stability threshold (the temperature at which volatile oil fragments begin to form), but instead will indicate bulk fragmentation occurring for a specified temperature and testing period. Because potential decomposition and generation of high pressure gas may occur at temperatures above 260 °C (500 °F), do not use this test method for aqueous fluids or other fluids which generate high-pressure gas at these temperatures. 1.2 DIN Norm 51528 and GB/T 23800 cover other test methods that are similar to this test method. 1.3 The applicability of this test method to siloxane-based heat transfer fluids has not been determined. 1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only. 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. For specific warning statements, see 7.2 , 8.8 , 8.9 , and 8.10 . 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 Heat transfer fluids degrade when exposed to sufficiently high temperatures. The amount of degradation increases as the temperature increases or the length of exposure increases, or both. Due to reactions and rearrangement, degradation products can be formed. Degradation products include high and low boiling components, gaseous decomposition products, and products that cannot be evaporated. The type and content of degradation products produced will change the performance characteristics of a heat transfer fluid. In order to evaluate thermal stability, it is necessary to quantitatively determine the mass percentages of high and low boiling components, as well as gaseous decomposition products and those that cannot be vaporized, in the thermally stressed heat transfer fluid. 5.2 This test method differentiates the relative stability of organic heat transfer fluids at elevated temperatures in the absence of oxygen and water under the conditions of the test. 5.3 The user shall determine to his own satisfaction whether the results of this test method correlate to field performance. Heat transfer fluids in industrial plants are exposed to a variety of additional influencing variables. Interaction with the plant's materials, impurities, heat build-up during impaired flow conditions, the temperature distribution in the heat transfer fluid circuit, and other factors can also lead to changes in the heat transfer fluid. The test method provides an indication of the relative thermal stability of a heat transfer fluid, and can be considered as one factor in the decision-making process for selection of a fluid. 5.4 The accuracy of the results depends very strongly on how closely the test conditions are followed. 5.5 This test method does not possess the capability to quantify or otherwise assess the formation and nature of thermal decomposition products within the unstressed fluid boiling range. Decomposition products within the unstressed fluid boiling range may represent a significant portion of the total thermal degradation.