1.1 本试验方法包括使用辐射温度计作为标准仪器校准难熔金属热电偶。本试验方法适用于不能暴露于氧化性大气中的热电偶类型。这些程序适用于温度高于800°C（1472°F）的热电偶校准。 1.2 校准方法适用于以下热电偶组件: 1.2.1 类型1- 裸线热电偶组件，其中真空或惰性气体或还原性气体是热电偶之间的唯一电绝缘介质。 1.2.2 类型2- 将松散配合的陶瓷绝缘件（如单孔或双孔管）放置在热电偶上的组件。 1.2.3 2A型- 将松散配合的陶瓷绝缘件（如单孔或双孔管）放置在热电偶上的组件，永久密封在松散配合的金属或陶瓷管中。 1.2.4 类型3- 模锻组件，其中耐火绝缘粉末被压缩在热电偶周围，并封装在由高熔点金属或合金制成的薄壁管或护套中。 1.2.5 类型4- 热电偶组件，其中一个热电偶为封闭端保护管形状，另一个热电偶为实心导线或杆，在封闭端管内同轴支撑。两个热电偶之间的空间可以填充惰性气体或还原性气体，或填充陶瓷绝缘材料，或保持真空。 1.3 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。 1.4 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 本试验方法旨在供电线制造商和热电偶制造商用于耐火金属热电偶的认证。 其目的是提供一种参考校准辐射温度计校准难熔金属热电偶的一致方法。辐射温度计校准和操作的不确定性，以及测试炉的正确构造和使用至关重要。 5.2 校准建立了特定温度和化学环境下特定热电偶的温度-电动势关系。然而，在真空、氧化、还原或污染环境中的高温校准或高温应用期间，根据温度分布，一个或两个热电偶的塞贝克系数可能会发生局部不可逆变化。 如果引入的不均匀性很大，热电偶的电动势将取决于测量结和参考结之间的温度分布。 5.3 在高温下，难熔金属热电偶的精度可能会受到通过热电偶组件陶瓷绝缘体的电气分流误差的限制。仔细选择绝缘体材料可以减少这种影响，但在大约2100°C以上，即使对于可用的最佳绝缘体，电分流误差也可能很大。

1.1 This test method covers the calibration of refractory metal thermocouples using a radiation thermometer as the standard instrument. This test method is intended for use with types of thermocouples that cannot be exposed to an oxidizing atmosphere. These procedures are appropriate for thermocouple calibrations at temperatures above 800°C (1472°F). 1.2 The calibration method is applicable to the following thermocouple assemblies: 1.2.1 Type 1— Bare-wire thermocouple assemblies in which vacuum or an inert or reducing gas is the only electrical insulating medium between the thermoelements. 1.2.2 Type 2— Assemblies in which loose fitting ceramic insulating pieces, such as single-bore or double-bore tubes, are placed over the thermoelements. 1.2.3 Type 2A— Assemblies in which loose fitting ceramic insulating pieces, such as single-bore or double-bore tubes, are placed over the thermoelements, permanently enclosed and sealed in a loose fitting metal or ceramic tube. 1.2.4 Type 3— Swaged assemblies in which a refractory insulating powder is compressed around the thermoelements and encased in a thin-walled tube or sheath made of a high melting point metal or alloy. 1.2.5 Type 4— Thermocouple assemblies in which one thermoelement is in the shape of a closed-end protection tube and the other thermoelement is a solid wire or rod that is coaxially supported inside the closed-end tube. The space between the two thermoelements can be filled with an inert or reducing gas, or with ceramic insulating materials, or kept under vacuum. 1.3 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. 1.4 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 This test method is intended to be used by wire producers and thermocouple manufacturers for certification of refractory metal thermocouples. It is intended to provide a consistent method for calibration of refractory metal thermocouples referenced to a calibrated radiation thermometer. Uncertainty in calibration and operation of the radiation thermometer, and proper construction and use of the test furnace are of primary importance. 5.2 Calibration establishes the temperature-emf relationship for a particular thermocouple under a specific temperature and chemical environment. However, during high temperature calibration or application at elevated temperatures in vacuum, oxidizing, reducing or contaminating environments, and depending on temperature distribution, local irreversible changes may occur in the Seebeck Coefficient of one or both thermoelements. If the introduced inhomogeneities are significant, the emf from the thermocouple will depend on the distribution of temperature between the measuring and reference junctions. 5.3 At high temperatures, the accuracy of refractory metal thermocouples may be limited by electrical shunting errors through the ceramic insulators of the thermocouple assembly. This effect may be reduced by careful choice of the insulator material, but above approximately 2100°C, the electrical shunting errors may be significant even for the best insulators available.