The Non-Steady-State Probe (NSSP) measurement method (also known as transient line source, thermal needle, hot needle, heat pulse- and hot wire technique) has the fundamental advantages that it is fast and absolute while the sample size is not critical. Hukseflux is specialized in NSSP design. Special models have been developed for in-situ field experiments. For permanent installation in soils, a dedicated model, TP01, is available. TP08 has been designed and tested in collaboration with the Applied Physics Group of Wageningen University.
Hukseflux specializes in Non-Steady-State probe design. The primary model of the Hukseflux product range is the TP02. This model offers optimal measurement accuracy by a combination of its design features. For some applications however the requirements regarding the sample size are such that the needle length and diameter of the TP02 are too large. For this category of samples, TP08 has been designed. Having a needle length of 70 mm, with the junction at around 17 mm from the tip, and a diameter of 1.2 mm, samples of around 80 ml can be analysed. (35 mm depth). In some cases samples can even be smaller (consult Hukseflux). In TP08 the reference junction of the thermocouple is located in the base. A high quality measurement with TP08 requires that not only the sample but also the base are at a stable (preferably the same) temperature. Usually this is achieved by clamping the base into the same material (metal) that holds the sample.
- Studies of ocean sediments
- Studies of small samples
- Studies of high cost samples (uranium sludge)
Areas of Application
|Test method||ASTM D 5334-00 and D 5930-97 IEEE Std 442-1981|
|Needle length||70 mm|
|Range (λ)||0.1 to 6 W/m.K|
|Sensitivity (ΔT)||Thermocouple K, ANSI MC96.1-1982|
|Temperature range (total sensor including cable)||-55 to +180 °C|
|Accuracy (@ 20 °C)||± (3% + 0.02) W/mK|
|Temperature dependence of the accuracy||± 0.02 %/K (additional)|
|Measurement cycle duration||200 s (typical)|
|Power requirements (switched)||3V, 1 Watt (max)|
|Medium / sample requirements||granular materials, powders, slurries, gels, pastes. Some samples require pre-drilling. Sample size: Min 20 mm radius. Min volume 80 ml. Smaller samples: consult Hukseflux. Caution: please consult the product manual for more details.|
|Protection needle and base||IP68|
|Protection total sensor||IP67|
|Options||• Container TP08: Because of the relative importance of the thermal equilibrium between base and sample, an optional container can be ordered with TP08.
• Alternative designs: Hukseflux is specialised in NSSP design. Alternative models, for instance smaller, more robust or temperature resistant have been manufactured on request.
• Permanent installation in soils: The dedicated model TP01 is specifically designed for long term monitoring. A separate brochure is available.
Frequently asked questions
How do I choose the right instrument for measuring thermal properties?
Hukseflux offers a wide range of products for material characterization and measurement of thermal conductivity.
We can offer assistance in choosing the right instrument. But first, you should ask yourself the following questions:
- what material should be analyzed?
- what are the conditions, for instance concerning temperature and pressure?
- what specimens are available?
- are there standards for my application?
- what level of accuracy do I need?
Hukseflux is a leading manufacturer of thermal conductivity measuring systems and sensors. We have prepared a guide which may assist you in choosing the proper instrument for measuring thermal properties of your material, whether it is soil, plastics, paints, composites, pastes and fluids.
Hukseflux is able to offer highest quality products at an acceptable price level. If we cannot offer you an acceptable solution ourselves, we will tell you who can. Please contact us for further assistance.
Where are the sensors (needle, probe, meter) for measuring thermal conductivity?
Hukseflux sells a range of complete measuring systems including sensors and Measurement and Control Units (MCU). We offer systems and needle type thermal properties sensors for use in the field and for use in laboratory environments.
These thermal properties sensors, TP02 and TP08, are also available as separate probes for use with the user’s own electronics, for instance Campbell Scientific CR1000.
Cannot find what you are looking for? Please contact us.
Can I get training or a rental system for the thermal conductivity measuring instrument of my choice?
Expert training for system operators
Although in general the systems can be operated by following manuals and standards, we can provide you with expert training. Training vastly improves the level of service to the third party, the efficiency of working with the equipment and reduces the uncertainty of the end result.
Unfortunately we have discontinued our rental services for all systems.