# Measurement Principles for the Quick Thermal Conductivity Meter QTM-710/QTM-700

- Introduction
- Measurement Principles for the Quick Thermal Conductivity Meter QTM-710/QTM-700
- Laser Flash Method Measurement Principles for thermal measurement device LFA-502
- Features by device type
- For what purposes is the device used?

## Quick Thermal Conductivity Meter QTM-710/QTM-700

In just one minute of placing the sensor on the sample, the thermal conductivity rate can be measured.

Measurement can be performed with simple operation for good repeatability.

## Measurement Principles for the Quick Thermal Conductivity Meter QTM-710/QTM-700

The QTM-710/QTM-700 measures thermal conductivity rate by the nonconstant heater wire method. The probe (sensor) 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.

The temperature rising curve is plotted in the line in the figure below, with the time axis scaled in logarithm.

The angle of the line is large with a low-conductivity sample (such as insulation), because its temperature increases rapidly, and the angle becomes smaller with a sample of high conductivity (such as metal).

In other words, the thermal conductivity rate of the sample can be found by the angle of the logarithmic temperature rise graph against the time axis.