In heat transfer, the thermal conductivity of a substance, k, is an intensive property that indicates its ability to conduct heat. For most materials, the amount of heat conducted varies (usually non-linearly) with temperature. Thermal conductivity is often measured with laser flash analysis. Alternative measurements are also established. Mixtures may have variable thermal conductivities due to composition. Note that for gases in usual conditions, heat transfer by advection (caused by convection or turbulence for instance) is the dominant mechanism compared to conduction. This table shows thermal conductivity in SI units of watts per metre-kelvin (W·m−1·K−1). Some measurements use the imperial unit BTUs per foot per hour per degree Fahrenheit ( = Sortable list This concerns materials at atmospheric pressure and around . Analytical list Thermal conductivities have been measured with longitudinal heat flow methods where the experimental arrangement is so designed to accommodate heat flow in only the axial direction, temperatures are constant, and radial heat loss is prevented or minimized. For the sake of simplicity the conductivities that are found by that method in all of its variations are noted as L conductivities, those that are found by radial measurements of the sort are noted as R conductivities, and those that are found from periodic or transient heat flow are distinguished as P conductivities. Numerous variations of all of the above and various other methods have been discussed by some G. K. White, M. J. Laubits, D. R. Flynn, B. O. Peirce and R. W. Wilson and various other theorists who are noted in an international Data Series from Purdue University, Volume I pages 14a–38a. This concerns materials at various temperatures and pressures. See also Laser flash analysis List of insulation material R-value (insulation) Thermal transmittance U-factor or U-value Specific heat capacity Thermal conductivity Thermal conductivities of the elements (data page) Thermal diffusivity Thermodynamics References Bibliography External links Heat Conduction Calculator Thermal Conductivity Online Converter - An online thermal conductivity calculator Thermal Conductivities of Solders Thermal conductivity of air as a function of temperature can be found at James Ierardi's Fire Protection Engineering Site Non-Metallic Solids: The thermal conductivities of non-metallic solids are found in about 1286 pages in the TPRC Data Series volume 2 at the PDF link here (Identifier ADA951936): http://www.dtic.mil/docs/citations/ADA951936 with full text link https://apps.dtic.mil/dtic/tr/fulltext/u2/a951936.pdf retrieved February 2, 2019 at 10:15 PM EST. Gasses and Liquids: The thermal conductivities of gasses and liquids are found in