The TLS-100 is a portable meter used to measure thermal conductivity and thermal resistivity of a variety of samples, including soil, rocks, concrete, and polymers. Tests can be performed with the push of a button and results are displayed instantly.
The Transient Line Source (TLS) meter follows ASTM D5334-14. The sensor needle consists of a thin heating wire and temperature sensor sealed in a 100 or 50 mm steel tube. The sensor is completely inserted into the sample to be tested. Heat is delivered to the sample using a constant current source (q) and the temperature rise is recorded over a defined period of time. The slope (a) from plot of temperature rise versus logarithm of time is used in the calculation of thermal conductivity (k). The higher the thermal conductivity of a sample, the lower the slope. For samples of low thermal conductivity, the slope will be higher.
| Materials | Soil, Rock, Concrete, & Polymers |
| Measurement Capabilities | Bulk Properties |
| Thermal Conductivity | 0.1 to 5 W/m•K |
| Thermal Resistivity | 0.2 to 10 m•K/W |
| Measurement Time | 3 min. (100mm) / 5 min. (50mm) |
| Reproducibility | Typically better than 2% |
| Accuracy | Typically better than 5% |
| Temperature Range | -40 to 100°C |
| Smallest Sample (100 mm) | 50 mm (diameter or square) x 100 mm |
| Smallest Sample (50 mm) | 50 mm (diameter or square) x 50 mm |
| Largest Sample Size | Unlimited |
| Standards | ASTM D5334-14, & IEEE 442-1981 |
Each TLS-100 comes equipped with the standard 100 mm sensor for testing of soil, soft materials, polymers and easy to drill materials. The needle sensor is fully inserted into an isothermal sample and a measurement is made with the push of a button. After 180 seconds, results are displayed for thermal conductivity and thermal resistivity. Saved results can also be exported to a computer, via Micro-SD card or USB connection.
Soil thermal Dryout Curves can be prepared by measuring the thermal conductivity of a sample at different moisture contents, as the sample dries from saturation. The typical drying approach involves heating the soil at an elevated temperature. The sample is removed, weighed, and measured for thermal conductivity at different time intervals, until it is fully dried
The 50 mm sensor was designed for testing hard samples, like rock and concrete. Drilling the required 4 mm diameter x 50 mm hole in rigid samples is easy with the provided masonry drill bit. When testing hard samples, a thermal contact grease is used to enhance contact between the sensor and sample.
