The Transient Line Source 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.
Best For Soil, Rock, Concrete, and Polymers
Standard Test | Temperature
Method | Range
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 displayed instantly. The second generation TLS-100 has many advancements, such as sensors which are auto-recognized, with corresponding testing parameters automatically loaded.
The Transient Line Source (TLS) meter follows ASTM D5334 and IEEE 442-2017. The sensor needle consists of a thin heating wire and temperature sensor sealed in a 150, 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. |
Reproducibility | ± 2% |
Accuracy | ± 5% |
Temperature Range | -40 to 100°C |
Largest Sample Size | Unlimited |
Standards | 100 mm: ASTM D5334, and IEEE 442-1981; 150mm: ASTM D5334, IEEE 442-1981, and IEEE 442-2017 |
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 convenient utility software and 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.
Materials | Soils, Pastes, Powders, and Solids |
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. |
Reproducibility | ±2% |
Accuracy | ±5% |
Temperature Range | -40 to 100°C |
Minimum Sample Size | 100 mm in length, 50 mm diameter |
Largest Sample Size | Unlimited |
Standards | ASTM D5334, IEEE 442-1981 |
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.
Materials | Concrete, Rock, and Polymers |
Measurement Capabilities | Bulk Properties |
Thermal Conductivity | 0.3 to 5 W/m•K |
Thermal Resistivity | 0.2 to 3.3 m•K/W |
Measurement Time | 3 min. |
Reproducibility | ±2% |
Accuracy | ±5% |
Temperature Range | -40 to 100°C |
Minimum Sample Size | 50 mm in length, 50 mm diameter |
Largest Sample Size | Unlimited |
Standards | Modified ASTM D5334 |
Optional 150 mm sensor for in-lab and in-field testing of soil and soft materials according to IEEE 442-2017. The needle is fully inserted into an isothermal sample and measurement is made with the push of a button. After 180 seconds, results are displayed for thermal conductivity and thermal resistivity.
Materials | Soils, Pastes, Powders, and Solids |
Measurement Capabilities | Bulk Properties |
Thermal Conductivity | 0.1 to 3 W/m•K |
Thermal Resistivity | 0.3 to 10 m•K/W |
Measurement Time | 3 min. |
Reproducibility | ±2% |
Accuracy | ±5% |
Temperature Range | -40 to 100°C |
Minimum Sample Size | 150 mm in length, 50 mm diameter |
Largest Sample Size | Unlimited |
Standards | ASTM D5334, IEEE 442-2017 |
The TLS 100 mm – vCp Sensor was designed for testing the thermal conductivity, thermal diffusivity, and specific heat of soil, soft or easy to drill materials.
Materials | Soils, Pastes, Powders, and Solids |
Measurement Capabilities | Bulk Properties |
Thermal Conductivity | 0.1 to 5 W/m•K |
Reproducibility | ±2% |
Accuracy | ±5% |
Thermal Diffusivity | 0.05 to 1.5 mm2/s |
Accuracy | ± 10% |
Volumetric Specific Heat | Up to 2.5 MJ/m3K |
Accuracy | ± 15% |
Temperature Range | -40 to 100°C |
Minimum Sample Size | 100 mm in length, 50 mm diameter |
Largest Sample Size | Unlimited |
Standards | ASTM D5334 |