Thermtest THW-L2

The Transient Hot Wire (THW-L2) Liquid Thermal Conductivity Meter is a portable measurement system for direct determination of the thermal conductivity of liquids and pastes. The THW-L2 follows international standard ASTM D7896-19, and was designed with speed and operational simplicity in mind.

THW-L2 Specification

MaterialsLiquids and Pastes
Measurement CapabilitiesBulk Properties
Thermal Conductivity0.01 to 2 W/m•K
Measurement Time< 2 seconds
ReproducibilityTypically better than 2%
AccuracyTypically better than 5%
Temperature Range 1-50°C to 100°C
Smallest Volume15 ml
Largest Sample SizeUnlimited
StandardsASTM D7896-14

1 Requires cooling/heating apparatus.

THW-L2 Highlights

Standard THW-L2 Sensor

The THW-L2 comes with the standard 60 mm sensor for testing of liquids and pastes. The sensor is fully inserted into an isothermal sample and measurements are made with the push of a button. In less than 2 seconds, results are displayed for thermal conductivity. Volumes as small as 15 ml can be tested. Measurements can also be controlled by a computer with the easy to use THW software.

Optional Dry Bath

Using the included THW-L2 software and optional dry bath, automated measurements of thermal conductivity with temperature (-10 to 90°C or 0 to 100°C) have never been more convenient. The THW software automatically controls the increments of temperature steps between the desired start and end temperatures to ensure isothermal conditions and test results are free of temperature drift effects. For wider ranges of temperature, additional cooling/heating options are available.



The THW-L2 is capable of testing low thermal conductivity, compressible insulations, without the liquid sample holder. Samples with minimum dimensions of 65 mm in length and 2 mm in thickness can be tested in a horizontal configuration, with the sensor sandwiched between the samples. Using the THW-L2, expanded polystyrene was measured as 0.031 W/m•K, which is within 5% of the literature values.

Sample Measurements



The Sample

Using the THW-L2, liquid samples of unlimited size can be tested. With the small volume cell insert, volumes as small as 15 mL can be measured. The instrument’s ability to control convection, using short test times, allows accurate measurements of a wide range of samples, with varying viscosities.

Approximate Time: 1 minute



Insert Sensor

Once the liquid has been poured into the sample holder, the sensor can be vertically inserted in place. For smaller sample volumes, position the small volume cell into the sample holder, prior to the addition of the sample and sensor.

Approximate Time: 1 minute



Run Experiment

The instrument can be controlled through the front panel with the push of a button, or through a Windows based computer software. Single temperature point measurements, as well as scheduled temperature intervals may be performed using the THW software.

Approximate Time: 1 minute



Exporting Results

Using the Windows based software, users can save, print, and export test results to Microsoft Excel, for further processing once testing is complete.

Approximate Time: 1 minute

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