TP02 - Probe for non-stationary measurement of thermal conductivity of materials
TP02 is a probe that offers the possibility of practical and quick measurement of thermal conductivity or thermal resistance of non-solid materials, such as granular materials (soil), backfill materials, sediments, powdery and pulpy materials, gels, pastes, mud, paints, adhesives, with the help of boreholes as well as solid samples in a non-stationary way. It is also known as the dynamic line source method, heat needle, hot needle, heat pulse or hot wire technique.

The device, which consists of a needle with two thermocouples, a cold one at the tip of the needle and a warm one in the upper part of the needle, works according to the principle of linear heating of the sample with a known electric power and time tracking of the temperature. The probe can measure samples with a thermal conductivity between 0.1 and 6 W/mK, with a measurement accuracy of ±3% + 0.02 W/mK at 20 °C. The length of the needle inserted into the measuring sample (medium) is 150 mm, the sample radius must be at least 20 mm.