1.1 本试验方法涵盖了使用便携式差分热电堆发射计测定不透明和高导热材料发射率的技术。该测试方法的目的是提供一种量化室温附近材料发射率的比较方法。 1.2 本试验方法不能取代试验方法 C835 ，这是测定总半球发射度的绝对方法，或测试方法 E408年 ，其中包括两种测定总法向发射度的比较方法。由于便携式发射度计的独特结构，可以对其进行校准以测量总半球发射度。 这可以通过比较发射计测量值和测试方法得到支持 C835 ( 1. ) . 2. 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 表面发射度测试: 5.1.1 如果材料表面具有低发射率，则通过辐射传递从表面进行的热传递会减少。由于使用绝缘材料的控制因素有时是冷凝控制或人员保护，因此必须了解低发射率会改变材料的表面温度。选择这些材料的一个可能标准是老化对表面发射度的影响问题。如果在使用过程中没有保持材料的初始低表面发射率，则材料的长期价值会降低。 5.1.2 该测试方法为现场低发射率表面的比较定期测试提供了一种手段。 通过这种方式，可以监测老化对反射性能的影响。 5.1.3 本试验方法测定总半球发射度的精度优于±0.02个单位。 ( 1. ) 校准标准的发射度应通过准确独立测量总半球发射度获得。本试验方法不适用于对红外辐射高度各向异性或透明的试样。本试验方法也不得用于具有显著热阻的试样（见 7.3.4 ). 5.1.4 一旦确定了可靠的发射度测量值，该值可用于计算物体表面的辐射热流。 例如，如果表面温度， T 1. ，以及周围的温度， T 2. ，则已知辐射热流Q 拉德 ，由以下公式得出: 哪里 A. 是曲面的面积，并且 A. 假设远小于周围的面积，或假设周围的发射度为单位。当与对流和传导热流结合时，辐射热流提供了来自表面的总热流（实践中描述了计算总热流的方法 C680型 ).

1.1 This test method covers a technique for determination of the emittance of opaque and highly thermally conductive materials using a portable differential thermopile emissometer. The purpose of the test method is to provide a comparative means of quantifying the emittance of materials near room temperature. 1.2 This test method does not supplant Test Method C835 , which is an absolute method for determination of total hemispherical emittance, or Test Method E408 , which includes two comparative methods for determination of total normal emittance. Because of the unique construction of the portable emissometer, it can be calibrated to measure the total hemispherical emittance. This is supported by comparison of emissometer measurements with those of Test Method C835 ( 1 ) . 2 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 Surface Emittance Testing: 5.1.1 Heat transfer from a surface by radiation transfer is reduced if the surface of a material has a low emittance. Since the controlling factor in the use of insulation is sometimes condensation control or personnel protection, it is important to understand that a low emittance will change the surface temperature of a material. One possible criterion in the selection of these materials is the question of the effect of aging on the surface emittance. If the initial low surface emittance of a material is not maintained during service, then the long-term value of the material is diminished. 5.1.2 This test method provides a means for comparative periodic testing of low emittance surfaces in the field. In this way the effects of aging on the reflective properties can be monitored. 5.1.3 This test method determines the total hemispherical emittance with a precision of better than ±0.02 units. ( 1 ) The emittances of the calibration standards shall have been obtained from accurate independent measurements of total hemispherical emittance. This test method shall not be used for specimens that are highly anisotropic or transparent to infrared radiation. This test method also shall not be used for specimens with significant thermal resistance (see 7.3.4 ). 5.1.4 Once a reliable emittance measurement has been determined, the value is available to be used to calculate radiative heat flow from the subject surface. For example, if the temperature of the surface, T 1 , and the temperature of the surroundings, T 2 , are known, then the radiative heat flow, Q rad , is given by: where A is the area of the surface, and either A is assumed to be much smaller than the area of the surroundings or the emittance of the surroundings is assumed to be unity. This radiative heat flow when combined with convective and conductive heat flows provides the total heat flow from the surface (a method for calculating total heat flow is described in Practice C680 ).