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A critical analysis of European standards for thermal measurements at high temperatures: I. History and technical background

机译：对欧洲高温热测量标准的严格分析：I.历史和技术背景

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Measurements on thermal insulations in the temperature range -20 deg C to 80 deg C using the guarded hot plate method in accordance with both international and national standards have been shown consistently to have the claimed uncertainty of better than +-2percent to +-3percent. However, national and international intercomparisons have shown that significantly higher uncertainties (from the order of +-10percent to +-18percent) occur when measuring using EN 12667, at temperatures from 100 deg C up to 600 deg C and higher. Recently, the Technical Committee 89 of the European standardization body CEN has established a working group (WG 11) with the task of reviewing the current standard EN 12667 to ensure that it is suitable for making reliable measurements at high temperatures to the required level of uncertainty for providing declared performance values for products. Historically it appears that the guarded hot plate exists in two forms of a basic design that differ essentially only in the use of different materials for operation at low and high temperatures. Both are based on the principles and models for room temperature ambient conditions with assumptions that these apply to an operation at high temperature. The current analysis has identified a number of potential sources of error or uncertainty that can arise due to the effects of differences in materials used together with those due to changes caused by the elevated temperature operating conditions. As a result, it is possible to recommended means to minimize these effects in order to prepare a separate EN standard to reduce the uncertainty level to +-5percent or better at elevated temperatures. These recommendations combined with a suggested protocol for undertaking measurements and proposals for further research are presented in the second part of this paper.
机译：根据国际和国家标准，使用保护性热板法在-20℃至80℃的温度范围内对隔热材料进行的测量已被一致证明不确定性优于+ -2％至+ -3％。但是，国内和国际的比较结果表明，在温度从100摄氏度到600摄氏度甚至更高的温度下使用EN 12667进行测量时，不确定性要高得多（从+ -10％到+ -18％）。最近，欧洲标准化组织CEN的技术委员会89建立了一个工作组（WG 11），其任务是审查当前的标准EN 12667，以确保它适合在高温下进行可靠的测量，达到要求的不确定度用于提供产品的声明性能值。从历史上看，受保护的热板以两种基本设计形式存在，它们的本质区别仅在于在低温和高温下使用不同的材料。两者均基于室温环境条件的原理和模型，并假设这些条件和模型适用于高温操作。当前的分析已经确定了许多潜在的误差或不确定性来源，这些误差或不确定性可能是由于所用材料的差异以及由于高温工作条件引起的变化所引起的材料差异所致。因此，可以建议采用最小化这些影响的方法，以准备单独的EN标准，以将不确定性水平降低到+ -5％或更高。这些建议，结合进行测量的建议方案和进一步研究的建议，将在本文的第二部分中介绍。

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