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Environmental measurement & analysis
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Thermal Conductivity Testers

The EKO Thermal conductivity tester is based on the thermopile core technology used in other solar radiation and heatflux sensors. It was developed with a special purpose for the quick inspection of vacuum leakages and insulation effectiveness for Vacuum Insulation Panel (VIP). Traditionally thermal conductivity testers need a long stabilizing time, however the HC-121 measures one VIP within 5 minutes because it checks the VIP's by simplified method.

The principle of this measurement is by placing a sensor on a flat surface of a VIP sample, and run a fixed amount of electric current. At this time, a heat flow will pass through the sample due to the thermal conductivity of this sample. The amount of heat that flow into the sensor becomes smaller if the thermal conductivity value of the sample is higher and it becomes larger if the thermal conductivity of the same is lower. It measures the temperature differences between the sample and inside the thermal resistance material of the sensor with differential thermocouple with these heat flows.


Product Model Description
HC-121 VIP Checker

HC-121 VIP Checker

HC-121 is used to check the performance (Good / non good) of vacuum insulator panels (VIP) by measuring …


HC-121 Contoller

Sensor input Differential Thermocouple voltage
Input range 10 mV
Measurement accuracy ± 0.025 mV
Heater curent 120 mA per channel
Number of input channels 5
Communication interface RS-232 (PC and optional bar code reader)
Dimensions 320 x 120 x 220
Weight  3 kg
Power  AC100 - 240 V, 5-/60 Hz, 3A
BAR code reader Optional

*VIP Sample size

150 ~ 760 mm

(difference with reference sample ±50mm)

*VIP Sample thickness

5 ~ 50 mm 

(difference with reference sample ±5mm @ 10mm)

Measurement range 1 - 9 mW/mK


Sensor Unit

Thermal conductivity 43.8 mW/mK (dry condition)
Thermal resistance 1.148 m2・K/W
Dimensions ø 52 mm, H117 mm 
Weight 1 kg
Heater 10W, 85Ω

Calibration procedure and traceability

The relationships between heat flow, temperature differences, and thermal conductivity are not linear due to all sorts of different conditions characteristic for each material, surface, thickness, dimensions, temperature, humidity. However the output of the Sensor (mV) and the thermal conductivity are considered to have a proportional relationship in a small thermal conductive range resulting in a straight-line approximation. Since the HC-121 can only perform a relative measurement it requires a characterized VIP sample for calibration in order to find the calibration coefficients a,b, and c of the slope intersection. These values are different for each sensor head. Therefore, before starting the evaluation on the VIP, the sensors of the Insulation Checker need to be calibrated.