THERMTEST THW-L2

Portable thermal conductivity meter for measurement of liquids and pastes

ASTM D7896-14

FEATURED TRANSIENT HOT WIRE CAPABILITIES

The Transient Hot Wire (THW-L2) Liquid Thermal Conductivity Meter is an advanced measurement system for direct determination of the thermal conductivity of liquids and pastes in accordance with ASTM D7896-14. The THW-L2 was designed with speed and operational simplicity in mind. With a single measurement of less than 2 seconds in duration, small volumes of liquids and pastes can be accurately and precisely measured for thermal conductivity. The THW-L2 utilizes a non-stationary measurement approach and rapid test times to limit convective effects for samples with a wide range of viscosities. The THW sensor consists of a thin heating wire 60 mm in length and is completely inserted into the sample to be tested. The sensor wire is heated using a constant current source (q) and the temperature rise is recorded by monitoring the change in electrical resistance of the wire. The slope (a) from the plot of temperature rise vs. logarithm of time is used in the calculation of thermal conductivity (k). For liquid samples of high thermal conductivity, the lower the slope. For liquid samples of low thermal conductivity, the higher the slope.

• Follows international standard: ASTM D7896-14
• Portable, Economical, & Accurate
• Results without the effects of convection
• Easy to use
• Optional thermoelectric dry bath for automated temperature testing

THW-L2 SPECIFICATIONS

¹ Requires cooling/heating apparatus.

PORTABLE. ECONOMICAL. ACCURATE.

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. The easy to use THW software enables measurements to be controlled via a computer. When used in conjunction with the optional thermoelectric dry bath, the software can even automate measurements of thermal conductivity with temperature.

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.

THERMAL CONDUCTIVITY OF INSULATION

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 MEASUREMENT

1

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

2

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

3

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 easy to use THW software.

Approximate Time: < 1 minute

4

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 minutes

APPLICATIONS USING THE THW-L2