Principal of Measurement

The probe consists of a single heater wire and thermocouple. When constant electric power (energy) is given to the heater, the temperature of the wire will rise in exponential progression. A temperature rising curve is plotted in a linear line below with the time axis scaled in logarithm. The angle of this line increases if the sample has less thermal conductivity (TC), and decreases if it has a higher TC. Therefore, TC of a sample can be determined from the angle of the rising temperature graphic line.

thermal conductivity formula

Probe Sensors

PD-11 (standard probe)
PD-13 (for measurement of hydrous or electrically conductive material like food or crude, concrete, and more
PD-NO needle probe sensor
PD-31 two-piece sample design

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Measure Thermal Conductivity with the QTM500

The QTM500 is a thermal conductivity meter that can provide results in as little as 60 seconds. The QTM500 can measure themal conductivity on many types of samples using its various probe sensors including material like:

Thermal insulating material like rock, wool, glass wool, formed resin
High heat insulation material or ceramics
Bread dough, mashed food, powders
Engine oil, silicone oil and more

Measuring Thin Sheet Material

With the diversification of materials there has been an increasing demand for measuring thermal conductivity of specimen such as slab, film (30 – 100 μm), sheet and thin plate (0.1 – 8 mm). To meet this demand, software "SOFT-QTM5EW" has been developed to work with the QTM-500 for quick measurement of thermal conductivity of thin materials. This software allows a PC to capture measurement data from the QTM-500, arrange the data, display the results, and record and store.

calc of thermal conductivity

Find the point of intersection where the deviation equals zero on the ε (deviation) versus λ (thermal conductivity) plot. The λ of this point is considered to be the thermal conductivity of the sample.