1.1 本试验方法描述了对称为“定向火焰温度计”（DFT）的非制冷传感器的一个或两个表面的半球热流的连续测量。 1.2 DFT由两块严重氧化的铬镍铁合金600板组成，在未暴露面上连接矿物绝缘金属护套（MIMS）热电偶（TCs，K型），并在板之间放置一层陶瓷纤维绝缘层。 1.3 可以使用几种方法对净热通量进行测试后计算。最精确的方法使用反向热传导代码。非线性逆热传导分析使用离散傅立叶变换的热模型，该模型具有与温度相关的热特性以及两个板的温度测量历史。 该代码提供了两个暴露面上的瞬态热流、DFT内的温度历史以及分析质量的统计信息。 1.4 第二种方法在DFT传感表面和绝缘层上使用瞬态能量平衡，该方法使用与反向计算中相同的温度测量值来估计净热流。 1.5 第三种方法使用逆滤波函数（IFF）提供净通量的近实时估计。可使用卷积型数字滤波算法实时计算离散傅立叶变换“正面”（暴露于热源的任一表面）的热流历史。 1.6 虽然该测量方法是为用于火灾和消防安全测试而开发的，但由于DFT的尺寸及其结构，该测量方法在潜在的应用领域相当广泛。 它已用于测量300 kW/m以上的热通量水平 2. 在高温环境中，高达约1250 °C，这是K或N型热电偶的公认上限。 1.7 离散傅立叶变换器的瞬态响应受MIMS-TC的响应限制。热电偶越大，瞬态响应越慢。对于连接到1.6 mm厚板上的直径为1.6 mm的MIMS-TC，典型的响应时间约为1到2秒。使用差动补偿器可以提高响应时间。 1.8 以国际单位制表示的数值应视为标准值。国际单位制后括号中给出的值仅供参考，不被视为标准值。 1.9 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。 1.10 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 需要热通量测量: 5.1.1 温度和热流密度的独立测量支持火灾和其他高温环境（如熔炉）工程模型的开发和验证。 对于防火材料和结构组件的测试，需要温度和热流来充分规定边界条件，也称为热暴露。单独的温度测量不能提供一套完整的边界条件。 5.1.2 温度是一个标量变量 主要变量 . 热流是一个矢量，它是一个 衍生变量 . 因此，它们应该分开测量，就像电流和电压在电气系统中一样。对于稳态或准稳态条件，分析基本上使用欧姆定律的热模拟。热电路使用温差代替压降，用热流代替电流，用热阻代替电阻。 与电气系统一样，如果不知道这三个参数中的至少两个（温降、热流密度或热阻），则无法完全指定热性能。对于火灾或消防安全测试等动态热实验，电容被体积热容取代。 5.1.3 由于表面温度不同，通过DFT测量的净热流可能不同于进入感兴趣测试项目的热流。另一种测量方法是使用水冷Gardon或S-B仪表测量总冷壁热通量。入射辐射通量可以通过使用能量平衡从任一测量中估算[Keltner，2007和2008] ( 16 , 17 ) ]. 对流通量可根据气体温度和对流传热系数估算， h [Janssens，2007年 ( 18 ) ]. 假设传感器在物理上接近感兴趣的测试项目；可以使用来自传感器的入射辐射和对流通量作为感兴趣测试项目的边界条件。 5.1.4 在标准化耐火试验中，如试验方法 E119 和 E1529 或ISO 834或IMO A754，熔炉温度控制为标准时间-温度曲线。在除试验方法外的所有方法中 E1529 ，隐式假设热暴露只能通过测量的炉膛温度历史来描述，并且可以在不同时间和地点重复。 然而，由于使用了设计非常不同的温度传感器进行炉膛控制，这些测试提供了非常不同的热暴露。因此，这些不同的热暴露历史会对同一物品产生不同的防火等级。历史上的变化多达50种 % 或更高的定性防火等级（例如，1 h） 不同熔炉或实验室之间的差异表明，时间-温度控制的假设并不充分。此外，由于传感器不同，垂直炉中的热暴露通常高于水平炉，水平炉地板上的热暴露通常高于天花板上的热暴露。这些原因为为什么需要进行温度和热流测量以提供一致的测试结果提供了支持。 5.1.5 在90年代中期，美国海岸警卫队授权对海上耐火试验中的问题进行研究，例如在不同的熔炉中获得的额定值存在较大差异。一个重要的结论是，如果没有较大的静态和动态不确定性，就无法仅通过炉膛温度测量来预测炉膛中的热暴露[Wittasek，N.A.，1996] ( 19 ) ]. 5.1.6 NIST对世贸中心灾难的调查得出的建议之一是，需要转向基于性能的规范和标准。为消防研究基金会编制的报告扩展了这一建议[Beyler，C.，等人，2008年 ( 20 ) ]. 这项工作的一部分涉及在耐火试验中进行更全面的测量，包括定量热流测量。 它还涉及“设计火灾”的开发和使用，并定义其与标准化测试方法的关系。 5.1.7 桑迪亚国家实验室在涉及危险品的运输事故方面的工作比较了规定方法和基于性能的方法[Tiesen等人，2010年 ( 21 ) ]. 5.1.8 加拿大国家研究委员会的工作使用了四（4）个不同的温度传感器来控制水平炉。热暴露差异（见中的定义 3.2.5 )高达100 % 在前10年 min[Sultan，M.，2006年和2008年 ( 22 , 23 ) ]. 假设来自不同传感器或同一传感器的不同安装的温度测量值实际上是炉膛温度，根据使用的温度测量方法，可以预测非常不同的热暴露。 5.1.9 在另一系列水平炉试验中，加拿大国家研究委员会（NRCC）研究了六（6）种不同温度传感器设计对大型水平炉耐火试验的影响[Sultan，2008] ( 23 ) ]. NRCC使用六种不同的温度传感器进行炉膛控制:试验方法 E119 屏蔽热电偶，ISO 834平板温度计，试验方法中的6 mm MIMS TC E1529 、定向火焰温度计和带接地和不接地接头的1.6 mm MIMS TC。天花板处的总热通量使用Gardon量规测量。结果表明，根据所用的测量方法，可能存在非常不同的热暴露。在前10年 在耐火试验中，综合热通量的变化系数为2。 5.1.10 Sultan，M.的报告（2006年和2008年） ( 22 , 23 ) 杨森，M.（2008） ( 18 ) 已经表明，很难在耐火试验中测量一个参数（如炉膛温度）并计算另一个参数（热流密度或热暴露）。 5.1.11 从中的讨论 5.1 强烈建议在火灾试验中独立测量温度和热流。 5.2 用于DFT: 5.2.1 虽然冷却和非冷却传感器都可以用于测量热流，但结果通常相差很大。水冷式传感器是一些委员会E5方法（测试方法）中使用的直读式Schmidt Boelter或Gardon仪表设计 E2683 和 E511 分别由小组委员会E21为这些传感器开发。 08 ). 5.2.2 有三种类型的被动或非冷却传感器可用于测量净热流。一种是由弗吉尼亚理工大学Diller等人开发的混合传感器（所谓的高温热流传感器，HTHFS）。其设计用于在没有水冷却的情况下测量到表面的热传递[Gifford，a.，Hubble，D.，Pullins，C.，和Diller，T.，2010] ( 4. ) ]. HTHFS需要一个校准系数，该系数是传感器温度的函数[Pullins和Diller，2010年 ( 24 ) ]. 另一种是所谓的“直写热通量传感器”，可以在25到860的温度下使用 °C[Trelewicz、Longtin、Hubble和Greenlaw，2015年 ( 25 ) ]; 该仪表需要校准系数。第三种是定向火焰温度计（DFT），由桑迪亚国家实验室（基于英国的工作）和其他地方开发，用于测量大型烟尘池火灾中的传热。 DFT不需要校准因子，这可能被视为一种混合优势。无源传感器通常具有更高的温度能力，主要基于约1250的K型或N型TC极限 °C。即使是水冷式，Gardon和Schmidt-Boelter压力表通常由于传感表面的污垢和其他影响而无法在温度下工作。DFT通常可以保存到1100左右 °C。它们非常坚固，不需要冷却，并且不易受到传感表面污垢的影响。这些特性简化了在广泛的火灾和其他应用中的安装。本标准仅针对DFT。看见 10.2.2 更深入地讨论热流计校准。 5.2.3 DFT的早期工作（及其数据分析技术）侧重于获取定量热通量数据，以帮助定义大型液态烃池或泄漏火灾中的热条件。 大型水池火灾可以在短至一分钟的时间内达到准稳定状态。因此，池火DFT设计为1.6 mm厚的板，以提供与火的快速平衡（这些火中的最大加热速率约为30 °C/s）。

1.1 This test method describes the continuous measurement of the hemispherical heat flux to one or both surfaces of an uncooled sensor called a “Directional Flame Thermometer” (DFT). 1.2 DFTs consist of two heavily oxidized, Inconel 600 plates with mineral insulated, metal-sheathed (MIMS) thermocouples (TCs, type K) attached to the unexposed faces and a layer of ceramic fiber insulation placed between the plates. 1.3 Post-test calculations of the net heat flux can be made using several methods. The most accurate method uses an inverse heat conduction code. Nonlinear inverse heat conduction analysis uses a thermal model of the DFT with temperature dependent thermal properties along with the two plate temperature measurement histories. The code provides transient heat flux on both exposed faces, temperature histories within the DFT as well as statistical information on the quality of the analysis. 1.4 A second method uses a transient energy balance on the DFT sensing surface and insulation, which uses the same temperature measurements as in the inverse calculations to estimate the net heat flux. 1.5 A third method uses Inverse Filter Functions (IFFs) to provide a near real time estimate of the net flux. The heat flux history for the “front face” (either surface exposed to the heat source) of a DFT can be calculated in real-time using a convolution type of digital filter algorithm. 1.6 Although developed for use in fires and fire safety testing, this measurement method is quite broad in potential fields of application because of the size of the DFTs and their construction. It has been used to measure heat flux levels above 300 kW/m 2 in high temperature environments, up to about 1250 °C, which is the generally accepted upper limit of Type K or N thermocouples. 1.7 The transient response of the DFTs is limited by the response of the MIMS TCs. The larger the thermocouple the slower the transient response. Response times of approximately 1 to 2 s are typical for 1.6 mm diameter MIMS TCs attached to 1.6 mm thick plates. The response time can be improved by using a differential compensator. 1.8 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard. 1.9 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. 1.10 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 Need for Heat Flux Measurements: 5.1.1 Independent measurements of temperature and heat flux support the development and validation of engineering models of fires and other high environments, such as furnaces. For tests of fire protection materials and structural assemblies, temperature and heat flux are necessary to fully specify the boundary conditions, also known as the thermal exposure. Temperature measurements alone cannot provide a complete set of boundary conditions. 5.1.2 Temperature is a scalar variable and a primary variable . Heat Flux is a vector quantity, and it is a derived variable . As a result, they should be measured separately just as current and voltage are in electrical systems. For steady-state or quasi-steady state conditions, analysis basically uses a thermal analog of Ohm's Law. The thermal circuit uses the temperature difference instead of voltage drop, the heat flux in place of the current and thermal resistance in place of electrical resistance. As with electrical systems, the thermal performance is not fully specified without knowing at least two of these three parameters (temperature drop, heat flux, or thermal resistance). For dynamic thermal experiments like fires or fire safety tests, the electrical capacitance is replaced by the volumetric heat capacity. 5.1.3 The net heat flux, which is measured by a DFT, is likely different than the heat flux into the test item of interest because of different surface temperatures. An alternative measurement is the total cold wall heat flux which is measured by water-cooled Gardon or S-B gauges. The incident radiative flux can be estimated from either measurement by use of an energy balance [Keltner, 2007 and 2008 ( 16 , 17 ) ]. The convective flux can be estimated from gas temperatures and the convective heat transfer coefficient, h [Janssens, 2007 ( 18 ) ]. Assuming the sensor is physically close to the test item of interest; one can use the incident radiative and convective fluxes from the sensor as boundary conditions into the test item of interest. 5.1.4 In standardized fire resistance tests such as Test Methods E119 and E1529 , or ISO 834 or IMO A754, the furnace temperature is controlled to a standard time-temperature curve. In all but Test Methods E1529 , implicit assumptions have been made that the thermal exposure can be described solely by the measured furnace temperature history and that it will be repeatable from time to time and place to place. However, these tests provide very different thermal exposures due to the use of temperature sensors with very different designs for furnace control. As a result, these different thermal exposure histories produce different fire ratings for the same item. Historical variations of up to 50 % or more in the qualitative fire protection ratings (for example, 1 h) between different furnaces or laboratories indicate that the assumptions for time-temperature control are not well founded. Also, due to different sensors, thermal exposure in a vertical furnace is generally higher than in a horizontal furnace, and thermal exposure on the floor of a horizontal furnace is generally higher than on the ceiling. These reasons provide support for why both temperature and heat flux measurements are needed to provide consistent test results. 5.1.5 In the mid-90’s, the U. S. Coast Guard authorized a study of the problems in marine fire resistance tests, such as large variations in the ratings obtained in different furnaces. One important conclusion was that the thermal exposure in furnaces could not be predicted solely from furnace temperature measurements without large static and dynamic uncertainties [Wittasek, N. A., 1996 ( 19 ) ]. 5.1.6 One of the recommendations that resulted from NIST’s investigation of the World Trade Center disaster was the need to move towards performance based codes and standards. A report developed for The Fire Protection Research Foundation expanded on this recommendation [Beyler, C., et al., 2008 ( 20 ) ]. Part of this effort involves making a more comprehensive set of measurements in fire resistance tests including quantitative heat flux measurements. It also involves the development and use of “design fires” and defining their relationship with standardized test methods. 5.1.7 Work at Sandia National Laboratories on transportation accidents involving hazardous materials compares the Prescriptive and Performance based approaches [Tieszen, et al., 2010 ( 21 ) ]. 5.1.8 Work by the National Research Council of Canada used four (4) different temperature sensors to control a horizontal furnace. Differences in the thermal exposure (see definition in 3.2.5 ) were as high as 100 % during the first 10 min [Sultan, M., 2006 and 2008 ( 22 , 23 ) ]. Assuming the temperature measurements from the different sensors or different installations of the same sensor are actually the furnace temperature, one can predict very different thermal exposures depending on which temperature measurement method is used. 5.1.9 In another series of horizontal furnace tests, the National Research Council of Canada (NRCC) studied the effect of six (6) different temperature sensor designs on fire resistance tests in a large, horizontal furnace [Sultan, 2008 ( 23 ) ]. NRCC used six different temperature sensors for furnace control: Test Methods E119 Shielded Thermocouple, ISO 834 Plate Thermometer, 6 mm MIMS TC from Test Methods E1529 , Directional Flame Thermometers, and 1.6 mm MIMS TCs with grounded and ungrounded junctions. Total heat flux at the ceiling was measured using a Gardon gauge. Results showed that very different thermal exposures are possible depending on the measurement method used. During the first 10 min of a fire resistance test, the integrated heat flux varies by a factor of two. 5.1.10 Reports by Sultan, M., (2006 and 2008) ( 22 , 23 ) and Janssens, M., (2008) ( 18 ) have shown it is difficult to measure one parameter in a fire resistance test (such as the furnace temperature) and calculate the other (heat flux or thermal exposure). 5.1.11 From the discussions in 5.1 , it is highly recommended that both temperature and heat flux be measured independently in fire tests. 5.2 Use for DFTs: 5.2.1 Although both cooled and non-cooled sensors can be used to measure heat flux, the results are generally quite different. Water-cooled sensors are the direct reading Schmidt-Boelter or Gardon gauge designs that are used in some Committee E5 Methods (Test Methods E2683 and E511 , respectively, have been developed for these sensors by Subcommittee E21.08 ). 5.2.2 There are three types of passive or un-cooled sensors that can be used to measure net heat flux. One is the hybrid sensor (so-called High Temperature Heat Flux Sensor, HTHFS) developed by Diller, et al., at Virginia Tech. It is designed to measure heat transfer to a surface without water cooling [Gifford, A., Hubble, D., Pullins, C., and Diller, T., 2010 ( 4 ) ]. The HTHFS requires a calibration factor that is a function of sensor temperature [Pullins and Diller, 2010 ( 24 ) ]. Another is the so-called “direct write heat flux sensor” which can be used at temperatures from 25 to 860 °C [Trelewicz, Longtin, Hubble, and Greenlaw, 2015 ( 25 ) ]; this gauge requires a calibration coefficient. The third is the Directional Flame Thermometer (DFT), which was developed at Sandia National Laboratories (based on work in the UK) and elsewhere for measuring heat transfer in large sooty pool fires. DFTs do not require a calibration factor, which may be viewed as a mixed benefit. The passive sensors typically have higher temperature capability, based mainly on the Type K or N TC limit of about 1250 °C. Even though they are water cooled, quite often Gardon and Schmidt-Boelter gauges do not survive in temperatures due to fouling of the sensing surface, and other effects. DFTs usually survive up to about 1100 °C. They are very rugged, require no cooling, and are not susceptible to fouling of the sensing surface. These characteristics simplify installation in a wide range of fire and other applications. This standard will only address DFTs. See 10.2.2 for a more thorough discussion of heat flux gauge calibrations. 5.2.3 Early work on DFTs (and the data analysis techniques for them) focused on acquiring quantitative heat flux data to help define the thermal conditions in large, liquid hydrocarbon pool or spill fires. Large pool fires can reach quasi-steady conditions in times as short as a minute. As a result, Pool Fire DFTs were designed with 1.6 mm thick plates to provide rapid equilibration with the fire (the maximum heating rate in these fires was approximately 30 °C/s).