GB/T 37796-2019 is a national standard for determining the thermal conductivity of insulating refractory materials. It specifies the test principles, equipment, procedures, and result calculation requirements for the calorimeter method, and is applicable to materials such as refractory fibers and their products, as well as shaped insulating products. Based on Fourier's law of heat conduction, the standard calculates thermal conductivity by measuring the heat absorbed by the calorimeter under conditions of steady-state heat transfer and a large temperature gradient. Relevant testing instruments include a thermal conductivity tester (comprising a heating chamber, calorimeter, and water circulation system), an electric drying oven, and a balance with a division value of 0.1g, paired with K-type or S-type thermocouples and a high-precision potentiometer to ensure the accuracy of the tests.