1.1This test method describes the continuous measurement of the heat flux normal to exposed surfaces and two-flux or bidirectional heat fluxes in high-temperature environments, such as furnaces and fires. Inverse heat conduction analysis and energy balance techniques are used to calculate the heat fluxes from two or more transient temperature measurements made with sensors called Directional Flame Thermometers (DFTs). 1.2 DFTs consist of two Inconel 600 plates with mineral insulated, metal-sheathed (MIMS) thermocouples (TCs) attached to the unexposed faces and a layer of ceramic fiber insulation sandwiched in between the plates. 1.3 The heat flux on both exposed faces is calculated with a nonlinear inverse heat conduction code using a thermal model of the DFT, with temperature dependent thermal properties, and the plate temperature measurements. The heat fluxes can be calculated in real-time and post-test if more detailed information is needed. 1.4 This general test method is quite broad in its field of application, size and construction. It has been used in high temperature environments, up to 1250 K, to measure heat flux levels up to 300 kW/m2 or more. This method can provide response times of less than 1 s. 1.5 The values stated in SI units are to be regarded as the standard. The values stated in parentheses are provided for information only. 1.6 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 and health practices and determine the applicability of regulatory limitations prior to use.
DFTs have been used in fire testing related to certification of hazardous material shipping containers for over 30 years. These test procedures are specified by US-DOT, US-NRC and IAEA. DFTs are specified in in fire resistance testing related to commercial buildings and petrochemical facilities.
KeywordsHeat Flux Measurement; Fire Safety Testing; Inverse Heat Conduction; Energy Balance; Process Control
The title and scope are in draft form and are under development within this ASTM Committee.Back to Top