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The Transient Hot-Wire (THW-L2) is a portable conductivity meter for the measurement of liquids.
Best for liquids
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 D7896-19. 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 (m) from the plot of temperature rise vs. logarithm of time is used in the calculation of thermal conductivity, the higher the slope.
Materials | Liquids |
|---|---|
Measurement Capabilities | Bulk Properties |
Thermal Conductivity | 0.01 to 2 W/m•K |
Measurement Time | < 2 seconds |
Reproducibility | Typically better than 2% |
Accuracy | Typically better than 5% |
Temperature Range* | -50 to 100°C |
Pressure | Ambient |
Smallest Volume | 15 ml |
Largest Sample Size | Unlimited |
Standard |
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 computer. When used in conjunction with the optional thermoelectric dry bath, the software can even automate measurements of thermal conductivity with temperature.with temperature.
The optional dry bath allows for automated measurements of thermal conductivity with temperature (-10 to 90 °C or 0 to 100 °C). 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 temperature ranges, additional cooling/heating options are available.
Using the Thermoelectric Dry Bath, the Thermtest THW-L2 is capable of testing liquids over a wide temperature range. In this application, deionized ultra-filtered (DIUF) water was tested from 10 to 70 °C, using the THW-L2. All test results were within 5% of the literature values.
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 min.
The instrument can be controlled through the front panel with the push of a button, or Windows-based computer software. Single temperature point measurements, as well as scheduled temperature intervals, may be performed using the easy to use THW-L2 software.
Approximate Time: < 1 min.
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 min.
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Models | ||||
Materials | Liquids, Pastes, and Powders | Liquids, Pastes, and Powders | Liquids, Pastes, and Powders | Liquids, Pastes, and Powders |
Testing Modules | Bulk | Bulk | Bulk | Bulk |
Other Materials | Solids with TPS | No | No | Solids with TPS, TLS |
Thermal Conductivity | 0.01 to 2 W/m•K | 0.01 to 2 W/m•K | 0.01 to 2 W/m•K | 0.01 to 1 W/m•K |
Sample Size | 20 mL | 20 mL | 15 mL | 15 mL |
Additional Properties | Thermal Diffusivity and Specific Heat | Thermal Diffusivity and Specific Heat | No | No |
Temperature Range | Room Temperature 10 to 200 °C | -50/-15/0 to 200 °C -160/-45/-15/0 to 300 °C | 10 to 200 °C | -50/-15/0 to 200 °C -160/-45/-15/0 to 300 °C | -50 to 100 °C | Room Temperature 10 to 40 °C |
Pressure | Up to 35 bar* | Up to 35 bar* | Ambient | Ambient |
Test Times | 1 second | 1 second | 1 second | < 5 seconds | 1 second |
Data-Points | 400 points/second | 100 points/second | 60 points/second | 60 points/second |
Thermal Conductivity Accuracy | 2 % | 2 % | 5 % | 5 % |
Repeatability | 1 % | 1 % | 2 % | 2 % |
Standards | ASTM D7896-19 | ASTM D7896-19 | ASTM D7896-19 | ASTM D7896-19 |
External Cooling Apparatus Required | No | Yes* | No | Yes* | Yes | Yes |
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