The Transient Hot Wire Liquid Thermal Conductivity Meter (THW-L1) is a precision analytical instrument for directly measuring the thermal conductivity, thermal diffusivity and specific heat of liquids and low viscosity pastes, from -150 to 300°C.  The THW-L1 is available in three models:

THW-L1: 10 to 200°C

THW-L1S: -50 to 200°C

THW-L1E: -100 / -150°C to 300°C

Picture 1. Thermtest THW-L1 Liquid Thermal Conductivity Meter.

The Thermtest Transient Hot Wire (THW-L1) Liquid Thermal Conductivity Meter is an advanced measurement system for direct determination of the thermal conductivity, thermal diffusivity and specific heat of liquids and pastes in accordance with ASTM D7896-19 – Standard Test Method for Thermal Conductivity of Engine Coolants and Related Fluids by Transient Hot Wire Liquid Thermal Conductivity Method.

The THW-L1 Meter was designed with speed and operational simplicity in mind. With a single measurement of 1 second in duration, small volumes of liquids and low viscosity pastes can be accurately and precisely measured for thermal conductivity, thermal diffusivity, and specific heat. The THW-L1 Meter uses a non-stationary measurement approach and rapid test times, limiting convective effects for samples with a wide range of viscosities (0.1 to 10,000,000 mPas).


This model of the THW-L1, has the widest range of cooling options and corresponding sensors available to reach temperatures of -150°C to 300°C.  Using our proprietary integrated temperature platform, the THW-L1E can be coupled with a wide variety of cooling options, this testing was done with the THW LN2 Package which allows testing as low as -150°C.  Recommended temperature range is -100°C due to higher LN2 consumption at lower temperatures.  Additionally, the THW Low Temp sensor was used, which uses ultra-low temperature gaskets for use at LN2 Temperatures.

Thermal Conductivity of Isopropanol

The thermal conductivity of isopropanol was measured with a THW-L1E sensor from 20oC to -110oC while pressure 4 bar was applied on the sample.

Figure 1 shows the cooling measurements of isopropanol 99 % v/v and the measurements taken every 10 minutes will the sample let to reach the ambient lab temperature.

The sharp “anomalous” thermal conductivity rise during the phase transition is expected during the melting of the samples.


Figure 1. Thermal Conductivity measurements of the Isopropanol sample showing all the measurement runs, first 20°C to -110°C and -110°C to 20°C.