GT Series

The GT series guiding tubes are accessories for Non-Steady-State Needle probes. They are intended to facititate measurements in hard soils, concrete, cement and bentonite. Also in case of measurements on large quantities of samples one can use several guiding tubes and one single needle.


GT01 guiding tubes 1webv1201Non-Steady-State Probes are used to determine the thermal conductivity of the surrounding medium. The method can applied in various substances such as sludges, fluids, foodstuff. The most frequent application however is in soils. A recurring problem is that insertion into hard soils, bentonites and cements is quite difficult. The main problem is that it is quite difficult to insert needles into these hard materials. The use of guiding tubes in many cases can solve this problem; The guiding tube should be inserted into the medium, and the needle can be inserted at a later stage.

Hukseflux is a leading supplier of Non-Steady-State Probes, and is the inventor of this guiding tube technology.

GT03 for NSSP probes 1webv1201In case of bentonites and cement the guiding tubes are cast into the material and experiments can be carried out later. In case of hard soils, a typical approach is to pre-drill a hole, insert the guiding tube, compact the soil again, and perform a measurement. In case of dryout experiments guiding tubes are inserted into the samples, dryout can then take place at high temperature (the needle is not inserted).

Suggested Use

  • Studies of ocean sediments
  • Studies of small samples
  • Studies of high cost samples (uranium sludge)


Test method ASTM D 5334-00 and D 5930-9, IEEE Std 442-1981
Delivery sets of 5 tubes, including caps
Material stainless steel
Needle ends welded
Protection tube with cap IP67

Frequently asked questions

What is thermal conductivity?

Thermal conductivity is the property of a material to conduct heat. Hukseflux is the present market leader in the design of needle type thermal conductivity sensors. The main application of these sensors is in measurement of the thermal properties of soils.