This standard describes the hot-wire/cross-array and resistance thermometer methods for the determination of thermal conductivity of non-carbonacious, dielectric refractory products and materials. Applicable refractories include dense and insulating shaped products, refractory castables, plastic refractories, ramming mixes, powdered or granular materials. Thermal conductivity values can be determined from room temperature to 1 250°C, or the maximum service limit of the refractory, or to the temperature at which the refractory is no longer dielectric. This methods are applicable to refractories with values less than 1,5 W/mK (cross-array) and less than 15 W/mK (resistance thermometer). In general it is difficult to make accurate measurements on anisotropic materials and the use of this method for such materials should be agreed between the parties concerned. NOTE The thermal conductivity of products with a hydraulic or chemical bond can be affected by the appreciable amount of water that is retained after hardening or setting and is released on firing. These materials may therefore require pre-treatment; the nature and extent of such pre-treatment and the period for which the test piece is held at the measurement temperature as a preliminary to carrying out the test, are details that are outside the scope of this standard and should be agreed between the parties concerned.